Under mass conversions, connections between **grams, moles **and **molecules** are established.

The **mole** is the chemical unit for the amount of a substance and serves as the bridge that connects grams to molecules, atoms, formula units and ions.

**Concept:** Avogadro’s Number, Moles, Molecules & Atoms

Before we begin, we should realize that mass conversions are going to play a very important and essential role in almost all the calculations we're going to do this semester.

We're going to start off by saying that the mole is the chemical unit for the amount of a substance. What exactly does this mean? Instead of a chemist ordering a hundred pounds of a particular element, a scientist could easily say 'I need 10.12 moles of carbon' or '100 moles of nitrogen'. It's basically a certain way that chemist communicate with each other to designate the amount, the weight they need of a particular element or compound.

We're going to say that one mole which you can write as this way, one mole contains 6.022x1023 entities. We're going to say that this special number has a name to it. This special number is known as Avogadro's number. When we say the word 'entities', entities means different things. When we say entities, entities can mean atoms, molecules or particles.

We're going to say we use atoms when we're dealing with a single or individual element. If I want 1,000 atoms of oxygen, I'm only talking about single oxygen. Remember oxygen can exists as a diatomic molecule, but here we're not talking about the molecule, we're talking about just the atom.

We're going to say we use molecules or particles when dealing with more than one element together or a compound, so just remember the difference. Atoms go with a single elements, molecules or particles goes with more than one element together or a compound. Compounds remember are just different elements combined together.

The words **atoms** and **ions** are used when talking about a single element and the words **molecules** and **formula units** are used when talking about more than one element together.

**Concept:** Atoms to Moles to Grams

How does this relate to our calculations we're going to do this semester?

Here we have two good examples of when do we use atoms versus when do we use molecules or particles. If we take a look, we say we have 6.022x1023 atoms of iron. Iron is there by itself, so that's why we're using the term atoms. Remember that's Avogadro's number. That number is always equal to one mole of whatever we're talking about. Since we have this many atoms of iron, that means we have one mole of iron.

We're going to say also that one mole of something is related to its weight. It's atomic mass which you'll find on your periodic table. If you look at your periodic table right now, look for iron, it's a transition metal. One mole of iron is equal to its atomic mass that you see on your periodic table. If you take a look, you'll see 55.85. That's representative of its atomic mass unit or we can say 55.85 grams per mole.

What we need to realize here, that there's a connection. We can go from atoms to moles to grams. I show you double arrows meaning we can go either way. So we can go from atoms to moles or moles to atoms. We can go from moles to gram or grams to moles. The arrows go both ways.

What we should realize here is that moles play the connection that's between atoms and grams. Remember you can’t go straight from atoms to grams without having first go through moles.

**Example:** Determine the mass (in grams) found in 7.28 x 10** ^{28}** nitrogen atoms.

**Concept:** Molecules to Moles to Grams

We've seen how atoms work. Now let's see how molecules work. We're going to start out again with Avogadro's number, but this time in terms of molecules of water. Remember that Avogadro's number is equal to one mole of whatever we're talking about, whether it be an atom, whether it be a molecule, whether it be particles, so that's equal to one mole of water.

One mole of any substance, whether it be an individual element or a compound, one mole of anything is equal to that objects molecular weight, its atomic mass. Here we have a mixture of different elements together, we have two hydrogens, we have one oxygen and water. To find out its total mass, we're going to add up each individual part.

We have two hydrogens, right? Because this little two here with the H, if you look on your periodic table, look for the atomic mass of hydrogen. When you look at it, you'll see that on your periodic table, its 1.008 grams and there are two hydrogens, so multiply that number times two. So that's 2.016 grams per mole.

Also, we have one oxygen which weighs 16 grams according to our periodic table, so that's 16 grams per mole. When you add those two numbers up together, that gives you the 18.016 grams per mole or 18.016 atomic mass units. That's where that number came from. We looked up each of the atomic masses of each individual element and then added them up together to get our answer.

Remember, Avogadro's number is always equal to one mole of whatever we're talking about. One mole of anything is just equal to the total mass of that object. If we take a look at this example, we're going to say it says, 'Determine how many molecules of carbon dioxide are found in 75 grams of carbon dioxide?'

Now, you should notice that this chart is similar to the one we just saw, except now instead of seeing atoms, we see molecules. You could also put particles in there too. Remember, there's a connection between molecules at moles, you can go from molecules to moles or moles to molecules and again there's a connection between moles and grams.

**Example:** Determine the how many molecules of carbon dioxide, CO_{2}, are found in 75.0 g CO_{2}.

**Problem:** If the density of water is 1.00 g/mL at 25^{o}C. Calculate the number of water molecules found in 1.50 x 10^{3} µL of water.

**Problem:** Calculate the number of oxygen atoms found in 783.9 g in copper (II) sulfate pentahydrate, CuSO_{4} x 5 H_{2}O.

**Problem:** The density of the sun is 1.41 g/cm^{3} and its volume is 1.41 x 10^{27} m^{3}. How many hydrogen molecules are in the sun if we assume all the mass is hydrogen gas?

**Problem:** A cylindrical copper wire is used for the fences around a house. The copper wire has a diameter of 0.0750 in. How many copper atoms are found in 5.160 cm piece? The density of copper is 8.96 g/cm^{3}. ( V = π x r^{2} x h )

Complete the following table.

**Part A **

Complete the second column of the table.

Enter your answers numerically separated by a comma.

**Part B **

Complete the third column of the table.

Enter your answers numerically separated by a comma.

Watch Solution

A chemist weighed out 101 g of silver. Calculate the number of moles of silver she weighed out. Be sure your answer has the correct number of significant digits.

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Which of the following contains the Fewest atoms? You shouldn't do a calculation here.

10.0 g Kr

10.0 g Na

10.0 g Ca

10.0 g Ae

10.0 g Li

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How many moles of zinc, Zn, are in 1.39 x 10^{24} Zn atoms?

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Convert 1.31 x 10^{24} atoms of carbon to moles of carbon.

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Hydrazine, N_{2}H_{4}, may react with oxygen to form nitrogen gas and water.

N_{2}H_{4} (aq) + O_{2} (g) → N_{2} (g) + 2H_{2}O (l)

If 2.35 g of N_{2}H_{4} reacts and produces 0.450 L of N_{2}, at 285 K and 1.00 atm, what is the percent yield of the reaction.

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Part A

What is the mass, in grams, of 1.50 mol of iron (III) sulfate?

Part B

How many moles of ammonium ions are in 6.935 g of ammonium carbonate?

Part C

What is the mass, in grams, of 1.40 x 10^{21} molecules of aspirin, C_{9}H_{8}O_{4}?

Express your answer using three significant figures.

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A chemist requires 0.537 mol Na_{2}CO_{3} for a reaction. How many grams does this correspond to?

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What is the mass (in grams) of 9.25 x 10^{24} molecules of methanol (CH_{3}OH)?

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How many moles of N are in 0.219 g of N_{2}O?

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How many moles of MgSiO_{3} are in 223 g of the compound?

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For we given elements, convert 1.00 gram of that element to moles.

How many moles of magnesium are in 1.00 gram?

How many moles of zinc are in 1.00 gram?

How many moles of xenon are in 1.00 gram?

Watch Solution

Calculate the molar mass of each compound given below.

Keep at least one decimal place in atomic masses from the periodic table.

a) Nal

b) Na_{2}S

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How many hydrogen ATOMS are there in 100.0 grams of H_{2}0?

(a) 3.35 x 10^{24} hydrogen atoms

(b) 6.69 x 10^{24} hydrogen atoms

(c) 9.23 x 10^{-24} hydrogen atoms

(d) 1.85 x 10^{-}^{23} hydrogen atoms

Watch Solution

What is the mass, in grams, of 2.5 moles of HCI?

(a) 14.6 grams

(b) 0.0685 grams

(c) 0.011 grams

(d) 91.3 grams

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How many moles of ammonia, NH_{3}, are there in 250 grams of ammonia? Do NOT include units in your answer.

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If 8.95 moles of C_{5}H_{12} reacts with excess O_{2}, how many moles of CO_{2} will be produced in the following combustion reaction?

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A mothball, composed of naphthalene (C_{10}H_{8}), has a mass of 1.30 g. How many naphthalene molecules does it contain?

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Complete the table.

Complete the second column of the table.

Enter your answers numerically separated by a comma.

Complete the third column of the table.

Enter your answers numerically separated by a comma.

Watch Solution

How many moles of atoms are in each elemental sample?

**Part A**

1.86 g Zn

**Part B**

26.6 g Ar

**Part C **

89.0 g Ta

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The 69.5-g sample of the compound X_{3}O_{4} contains 19.2 g of oxygen atoms. What is the molar mass of element X?

Watch Solution

A chemist requires 0.786 mol Na_{2}CO_{3} for a reaction. How many grams does this correspond to?

Watch Solution

Calculate the following in 6.00 g Li_{3}PO_{4 }

a) Li^{+} ions

b) grams O

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What is the mass (in grams) of 9.88 x 10^{24} molecules of methanol (CH_{3}OH)?

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What is the mass of exactly 1 mol of the following compounds?

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How many grams of carbon, C, would contain the same number of atoms as 32.066 g of sulfur, S?

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A typical adult body contains 6 liters of blood. The hemoglobin content of blood is about 15.5 g/100 mL of blood. The approximate molecular weight of hemoglobin is 64, 500 g/mol. How many moles of hemoglobin are present in a typical adult?

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How many grams of phosphorus, P, would contain the same number of atoms as 58.693 g of nickel, Ni?

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A sugar contains approximately 2.4 x 10^{17 }(C_{12}H_{22}O_{11}) molecules. What is its mean in milligrams? Express your answer using two significant figures.

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A sugar crystal contains approximately 2.1 x 10^{17} sucrose (C_{12}H_{22}O_{11}) molecules.

What is its mass in mg?

Express your answer using two significant figures.

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Calculate the mass in grams of 11.6 mol of chromium(III) sulfate decahydrate. Enter your answer in scientific notation.

Watch Solution

Be sure to answer all parts.

Calculate the mass in grams of 7.25 x 10 ^{18} molecules of diarsenic pentaoxide. Enter your answer in scientific notation.

Watch Solution

Be sure to answer all parts.

Calculate the number of H^{-} ions in 61.0 g of CaH _{2}.

Enter your answer in scientific notation.

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Enter your answer in the provided box.

Calculate the mass in grams of 3.88 mol of LiMnO _{4}.

Watch Solution

Be sure to answer all parts.

The atomic mass of Cl is 35.45 amu, and the atomic mass of Al is 26.98 amu. What are the masses in grams of 3.3356 mol of Cl atoms and of 7.9360 mol of Al atoms?

Watch Solution

How many moles of aspirin, C_{9}H_{8}O_{4}, are in a 500 mg tablet?

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What is the mass of 0.500 mol of carbon tetrachloride CCl _{4}?

a. 76.9 g

b. 308 g

c. 3.25 x 10^{-3}g

d. 154 g

Watch Solution

How many helium atoms are contained in 3.75 moles of helium?

a. 1.23 x 10^{24} helium atoms

b. 9.03 x 10^{24} helium atoms

c. 1.61 x 10^{23} helium atoms

d. 6.50 x 10^{25} helium atoms

e. 2.26 x 10^{24} helium atoms

Watch Solution

A chemist requires 0.900 mol Na_{2}CO_{3} for a reaction. How many grams does this correspond to?

Watch Solution

Calculate the molar mass of each compound given below. Keep at least one decimal place in atomic masses from the periodic table.

a. LiCl ________ g/mol

b. K_{3}N__________ g/mol

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A sample of C_{3}H_{8} has 6.40 x 10^{4} H atoms.

How many carbon atoms does the sample contain?

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Brontis is working in his lab. To continue his experiment, he needs to calculate the total number of ions in 3.13 mol of MgCl_{2}. Calculate the total number of ions in 3.13 mol of MgCl _{2}.

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How many moles of MgS_{2}O_{3} are in 243 g of the compound?

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How many atoms are in 159g of calcium?

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How many moles of N are in 0.171 g of N _{2}O?

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Calculate the following in 7.54 g Li_{3}PO_{4}.

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Tia has a sample of pure gold (Au). She weighed the sample and the result was 46.7 grams. Tia wants to determine the number of atoms in the sample. Calculate the number of atoms in 46.7 g of pure gold.

Watch Solution

What is the mass (in grams) of 9.50 x 10 ^{24} molecules of methanol (CH_{3}OH)?

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How many grams of iron (III) oxide are there in a 0.125-mole sample of iron (III) oxide?

a. 6 23 grams

b. 20.0 grams

c. 17.5 grams

d. 0.346 grams

e. 32.3 grams

f. 1.95 grams

Watch Solution

Calculate the molar masses of the following atmospheric molecules:

a. CO

b. N_{2}O

c. CH_{4}

d. NO_{2}

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What is the mass of 0.111 mole of MgCO_{3}?

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How many total atoms are in 0.830 g of P_{2}O_{5}?

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How many grams of hydrogen are in 92 g of CH_{4}O?

a. 5.8

b. 4.0

c. 120

d. 12

e. 63

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1 mole of which of the following will have the largest mass?

a. magnesium

b. rubidium

c. neon

d. mercury

e. 1 mole of any element will contain the same mass

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Calculate the number of moles of oxygen atoms in 35.2 grams of oxygen.

a. 2.20 moles

b. 4.42 moles

c. 1.13 moles

d. 0.54 moles

e. 2.57 moles

Watch Solution

Calculate the amount, in moles, of each of the following. You may round atomic masses to one decimal place.

21.1 g Na_{2}S_{2}O_{8}

Express your answer with the appropriate units.

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Calculate the amount, in moles, of each of the following. You may round atomic masses to one decimal place.

15.6 g SF_{6}

Express your answer with the appropriate units.

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Calculate the number of molecules in 5.00 moles H2S. Express your answer numerically in molecules.

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How many calcium ions are there in 4.14 mol Ca_{3}N_{2}? Express your answer to three significant figures.

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Which of the following could you reasonably measure on a typical laboratory scale or balance?

a. 1 molecule of NO2

b. 1 mole of marbles

c. 1 mole of Na2SO4

d. 1 atom of gold

Watch Solution

A small kidney stone might contain 0.47 g of uric acid (C _{5}H_{4}N_{4}O_{3}).

**Part A**

How many micromoles of uric acid are contained in this stone? Express your answer using two significant figures.

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On another planet, the isotopes of titanium have the following natural abundances.

What is the average atomic mass of titanium on that planet?

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If you have 213.12g of Ca _{3}(PO_{4})_{2}, how many moles do you have?

How many grams of NaCl are there in 0.2611 mol?

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What is the average molecular weight (in g/gmol) of the following mixture: 10.0 mole% C_{2}H_{5} OH. 75.0 mole% C_{4}H_{8}O_{2}, and 15.0 mole% CH_{3}COOH.

Select one:

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A chemist determines by measurements that 0.0650 moles of iodine solid participate in a chemical reaction. Calculate the mass of iodine solid that participates.

Be sure your answer has the correct number of significant digits.

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A chemist requires 0.450 mol Na_{2}CO_{3} for a reaction. How many grams does this correspond to?

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How many atoms are in 171 g of calcium?

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What is the percentage of iron in iron(III)oxide?

a. 30%

b. 70%

c. 60%

d. 40%

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Calculate the mass of 1.5 mol of C_{6}H_{12}O_{6}.

a. 6.022 x 10^{23} g C_{6}H_{12}O_{6}

b. 270 g C_{6}H_{12}O_{6}

c. 180 g C_{6}H_{12}O_{6}

d. 1.5 g C_{6}H_{12}O_{6 }

_{}

Watch Solution

How many moles of magnesium are in a 9.00 g sample of the metal?

Watch Solution

Be sure to answer all parts.

How many moles and numbers of ions of each type are present in the following aqueous solution?

377 mL of 0.285 g aluminum sulfate/L:

Watch Solution

How many grams are contained in 1.90 mol of each compound? Do not convert these answers to scientific notation.

a. HCI g

b. Na_{2}SO_{4} g

Watch Solution

Be sure to answer all parts.

How many grams are contained in 3.90 mol of each compound? Do not convert these answers to scientific notation.

a. C_{2}H_{2} g

b. AI(OH)_{3} g

Watch Solution

Be sure to answer all parts.

How many moles are contained in each number of grams of table sugar (C _{12}H_{22}O_{11} molar mass 342.3 g/mol)? Enter your answer in scientific notation.

a. 95.0 g

b. 0.0440 g

Watch Solution

Be sure to answer all parts.

How many moles are contained in each number of grams of fructose (C _{6}H_{12}O_{6}. molar mass 180.2 g/mol), a carbohydrate that is about twice as sweet as table sugar? "Lite" food products use half as much fructose table sugar to achieve the same sweet taste, but with fewer calories. Enter your answer in scientific notation.

a. 0.720 g

b. 6.10 g

Watch Solution

Be sure to answer all parts.

What is the mass in grams of each quantity of lactic acid (C _{3}H_{4}O_{3} molar mass 90.08 g/mol) the compound responsible for the aching feeling of tired muscles during vigorous exercise?

a 7.50 mol

b. 0.540 mol

Watch Solution

How many moles are contained in each number of grams of fructose (C _{6}H_{12}O_{6} molar mass 180.2 g/mol), a carbohydrate that is about twice as sweet as table sugar? "Lite" food products use half as much fructose as table sugar to achieve the same sweet taste, but with fewer calories. Enter your answer in scientific notation.

a. 19.0 g

b. 0.0820 g

Watch Solution

How many atoms of titanium are there in 0.500 mole of each of the following?

Watch Solution

Composition of Seawater A 1-liter sample of seawater contains 19.4 g of CI^{-}, 12.77 g of Na^{+}, and 1.79 g of Mg^{2+}.

(a) How many moles of each ion are present?

(b) If we evaporated the seawater, would there be enough CI^{-} present to form the chloride salts of all the sodium and magnesium present?

Watch Solution

How many moles of nitrogen, N, are in 69.0 g of nitrous oxide, N_{2}O?

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Calculate the number of particles in each of the following. 0.135 mol iron atoms, Fe. 0.252 mol nitrogen molecules, N2. 0.677 mol iron (III) nitride formula units.

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Iron reacts slowly with oxygen and water to form a compound commonly called (Fe_{2}O_{3} 4H_{2}O). For 35.7 kg of rust, calculate the following quantities.

(a) The moles of compound: ___moles of rust

(b) The moles of Fe_{2}O_{3}

(c) The grams of iron:

Watch Solution

Calculate the mass in kilograms of 32.7 mol of CuCl_{2} + H2O.

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Calculate the number of O atoms in 0.00105 g of CaSO4•2H2O

______ x 10^{___} O atoms (Enter your answer in scientific notation.)

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The mineral galena is composed of lead(II) sulfide and has an average density of 7.46 g/cm^{3}.

(a) How many moles of lead(II) sulfide are in 6.35 ft^{3} of galena?

(b) How many lead atoms are in 8.69 dm^{3} of galena?

(Enter your answer in scientific notation.)

Watch Solution

Calculate the formula mass for each of the following halogen compounds to five or more significant figures:

(a) NalO3 (antiseptic)

(b)C14H9Cl6 (DDT)

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How many atoms are in 183 g of calcium?

Watch Solution

Calculate the mass (in g) of a single maltose molecule (C12H22O11).

Express your answer using four significant figures

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Ascorbic acid, or vitamin C (, molar mass = 176 g/mol), is a naturally occurring organic compound with antioxidant properties. A healthy adult's daily requirement of vitamin C is 70-90 mg. A sweet lime contains 2.88 times 10^-4 mol of ascorbic acid. To determine whether the ascorbic acid in a sweet lime meets the daily requirement, calculate the mass of ascorbic acid in 2.88 x 10^-4 mol of ascorbic acid. Express the mass in grams to three significant figures.

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The mass of an average blueberry is 0.76 g and the mass of an automobile is 2200 kg . Find the number of automobiles whose total mass is the same as 1.0 mol blueberries. Express your answer using two significant figures.

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Silver chloride, often used in silver plating, contains 75.27% Ag. Calculate the mass of silver chloride in grams required to make 6.0 g of silver plating.

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Silver chloride, often used in silver plating, contains 75.27% Ag.

Calculate the mass of silver chloride required to plate 225 mg of pure silver.

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The world population is estimated to be approximately 7 billion people.

How many moles of people are there? Express your answer using one significant figure and include the appropriate units.

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How many moles (of molecules or formula units) are in each sample?

a. 62.20 g CF_{2}Cl_{2}

b. 21.3 kg Fe(NO_{3})_{2}

c. 0.1911 g C_{8}H_{1}_{8}

d. 130 kg CaO

Watch Solution

How many molecules (or formula units) are in each sample?

a. 52.03 g CCl_{4}

b. 73.85 kg NaHCO_{3}

c. 123.22 g C_{4}H_{10}

d. 3.15 × 10^{4} g Na_{3}PO_{4}

Watch Solution

How many moles (or molecules or formula units) are in each sample?

a. 20.0 g NO_{2}

b. 1.35 kg CO_{2}

c. 40.4 g KNO_{3}

d. 102.3 kg Na_{2}SO_{4}

Watch Solution

How many 150-mg aspirin tablets can be made from 15.0 kg of aspirin?

a. 100,000

b. 1,000,000

c. 10000

d. 10,000

e. 10,000,000

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What is the mass of a sample of water containing 3.55 x 10 ^{22} molecules of H_{2}O?

Watch Solution

a. How many moles of atoms are in 8.00 g of 13C?

b. Based on your answer in Part A, calculate the number of atoms in this amount of 13C?

c. Based on your answer in Part B, how many electrons are in this amount of 13C?

d. Based on your answer in Part B, how many neutrons are in this amount of 13C?

Watch Solution

Determine the number of moles of oxygen atoms in each of the following:

4.49 mol H_{2}O_{2}

2.17 mol N_{2}O

2.33 × 10^{−2} mol H_{2}CO_{3}

24.3 mol CO_{2}

Watch Solution

a. Calculate the formula weight of ethanol, C _{2}H_{5}OH.

b. Calculate the formula weight of Mg(NO _{3})_{2}.

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How many moles of atoms are in 9.00 g of ^{13}C?

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How many grams of CO _{2} are in 2.1 mol of the compound?

a. 21.0 g

b. 44.0 g

c. 66.0 g

d. 92.4 g

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Determine the mass of oxygen in a 7.2 g sample of Al _{2}(SO_{4})_{3}.

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Find the number of ibuprofen molecules in a tablet containing 200.0 mg of ibuprofen (C_{13}H_{18}O_{2}).

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In the gaseous state, chlorine exists as a diatomic molecule Cl _{2} (Molar mass = 70.9 g/mol). Calculate the number of moles of chlorine present in 150 g of chlorine gas.

Express the quantity in moles to three significant figures.

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How many moles of water, H_{2}O, contain 2.0 × 10^{22} molecules of water?

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What is the mass, in grams, of 1.24 mol of water, H _{2}O? Express the mass in grams to three significant figures.

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How many molecules are contained in the 254 grams of CH _{4}? The molar mass of CH_{4} is 16 grams/mole.

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Calculate the molar mass of ammonium phosphate (NH _{4})_{3}PO_{4} to correct sig. fig.

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Calculate the molar mass of ALUM, KAl(SO _{4}) _{2 }**. **12H_{2}O or potassium aluminum sulfate dodecahydrate. Be sure to include the twelve waters of hydration in the molar mass.

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The molar mass of potassium phosphate (K _{3}PO_{4}) is

A) 173.17

B) 251.37

C) 212.27

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How much does one sucrose molecule weigh in grams?

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Calculate the mass of 1.00 x 10 ^{24} (a septillion) molecules of water.

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What is the molar mass of aspirin, C_{9}H_{8}O_{4}?

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Calculate the molar mass of potassium hydroxide (KOH).

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The molar mass of zinc is 65.39 g/mol. How many moles of zinc are there in a 75.0 g sample of zinc?

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Determine the molar mass of sodium bicarbonate (from periodic table).

molar mass of Na _____ x 1 mol Na = _____

molar mass of H _____ x 1 mol H = _____

molar mass of C _____ x 1 mol C = _____

molar mass of O _____ x 3 mol O =

Sum for total molar mass _____

Watch Solution

What is the molar mass of calcium phosphate, Ca _{3}(PO_{4})_{2}?

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Calculate the molar mass of Cl _{2} if 1.27 x 10^{22} molecules of gaseous Cl _{2} have a mass of 1.5g.

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Calculate the molar mass of sodium chloride, NaCl (from the periodic table Na = 22.99 and Cl = 35.45).

a) 6.745 g/mole

b) 58.44 g/mole

c) 74.55 g/mole

d) 67.45 g/mole

e) 19.00 g/mole

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Determine the molar mass of potassium hydrogen phthalate (KHP). The molecular formula is KHC_{8}H_{4}O_{4} .

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The molar mass of HNO_{3} is 63.01g/mol, perform each of the following conversions

i) convert 13.9 g of HNO_{3} to moles and

ii) convert 2.507 moles of HNO_{3} to grams

Watch Solution

How many moles are there in 7.0 mL of N,N-dimethylaniline? Density of N,N-dimethylaniline is 0.956 g/mL and its molar mass is 121.19 g/mol. Show your work.

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What is the molar mass of magnesium hydroxide, Mg(OH) _{2}, a common antacid?

(A) 58 g/mol

(B) 56 g/mol

(C) 42 g/mol

(D) 41 g/mol

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Calculate the error for the molar mass of acetic acid, CH _{3}CO_{2}H. The atomic masses for each element are C = 12.0106 ± 0.0010, H = 1.00798 ± 0.00014, and O = 15.9990 ± 0.0008

Watch Solution

What is molar mass of Na _{2}CO_{3}?

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If you have 20.0 g of carbon dioxide gas, how many molecules of CO _{2} do you have?

A) 4.30 x 10^{23} molecules of CO_{2}

B) 2.74 x 10^{23} molecules of CO_{2}

C) 5.30 x 10^{26} molecules of CO_{2}

D) 1.46 x 10^{-21} molecules of CO_{2 }

E) 7.55 x 10^{-25} molecules of CO_{2}

Watch Solution

Consider the compound C_{2}H_{4}O_{2}. How many grams of oxygen are in 3.0 grams of it?

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You ate 5.0g of sugar (C_{6}H_{12}O_{6}). This quantity of sugar contains oxygen that is equivalent to how many moles of ozone (O_{3})?

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You ate 97.0g of NaCl. How many sodium ions does this quantity of NaCl contain?

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If you drink 225.0 g of pure water, about how many molecules of water do you drink?

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How many atomic mass units is 1 mole of water?

Watch Solution

Your car is 4.48 metric tons. How many times more massive is your car than an aluminum (Al) atom?

Watch Solution

How many moles of carbon atoms are present in a piece of diamond which has a volume of 1.00 cm^{3}? The density of diamond is 3.53 g/cm^{3}.

Watch Solution

How many atoms are contained in one formula unit of aluminum dichromate, Al_{2}(Cr_{2}O_{7})_{3}?

a. 14

b. 25

c. 27

d. 29

e. none of these

Watch Solution

Calculate the average mass, in grams, of an O_{2} molecule.

a. 32.0

b. 2.00

c. 2.66 x 10^{-23}

d. 1.88 x 10^{-22}

e. 5.31 x 10^{-23}

Watch Solution

If 200.0 g of zinc sulfide contains 134.2 g of zinc, what mass of zinc in g is contained in 3.3 kg of zinc sulfide?

Watch Solution

6.02 x 10^{21} molecules of an unknown substance X has a mass of 11.0 grams. What is the molar mass of X in g/mole?

(A) 110 g/mol

(B) 220 g/mol

(C) 1100 g/mol

(D) 2200 g/mol

(E) cannot be determined without the formula of X

Watch Solution

Calculate the number of nitrogen atoms in 240. g of ammonium nitrate.

(A) 2.01 x 10^{23} nitrogen atoms

(B) 6.02 x 10^{23} nitrogen atoms

(C) 1.20 x 10^{24} nitrogen atoms

(D) 1.81 x 10^{24} nitrogen atoms

(E) 3.61 x 10^{24} nitrogen atoms

Watch Solution

32.0 grams of the element oxygen:

(A) contain 6.02 x 10^{23} atoms of oxygen

(B) contain 1.204 x 10^{24} molecules of oxygen

(C) contain the same number of oxygen atoms as 18.0 g of water

(D) contain the same number of oxygen atoms as 72.0 g of water

(E) contain the same number of oxygen atoms as 90.0 g of water

Watch Solution

Calculate the number of moles in 55.0 g of magnesium hydroxide.

(A) 0.943 mol

(B) 1.33 mol

(C) 1.83 mol

(D) 2.89 mol

(E) 5.68 x 10^{23} mol

Watch Solution

What is the mass of 4.50 x 10^{22} atoms of magnesium, Mg?

(A) 0.0748 g

(B) 0.182 g

(C) 0.897 g

(D) 1.82 g

(E) 18.2 g

Watch Solution

Calcium fluoride is used to fluoridate drinking water. Calculate its molar mass in g/mol.

(A) 118.15

(B) 99.15

(C) 78.07

(D) 59.08

(E) 38.00

Watch Solution

6.02 x 10 ^{21} molecules of an unknown substance X has a mass of 2.00 grams. What is the molar mass of X in g/mole?

(A) 0.02 g/mol

(B) 0.2 g/mol

(C) 20 g/mol

(D) 200 g/mol

(E) 2000 g/mol

Watch Solution

How many fluorine atoms are present in 19.75 g of the Freon C _{2}HBrClF_{3}?

(A) 1.81 x 10^{23}

(B) 6.02 x 10^{23}

(C) 6.69 x 10^{21}

(D) 6.03 x 10^{22}

(E) 2.23 x 10^{23}

Watch Solution

Calculate the mass in grams of 1.505 x 10 ^{23} molecules of CH _{4}.

(A) 4 g

(B) 16 g

(C) 40 g

(D) 64 g

(E) 2.4 x 10^{24} g

Watch Solution

How many moles of water contain 2.22 x 10 ^{24} molecules of water?

(A) 3.69 moles

(B) 0.272 moles

(C) 2.72 moles

(D) 36.9 moles

(E) 1.34 x 10^{48} moles

Watch Solution

You must use Dimensional Analysis and answer the question.

A gaseous sample of methane, CH_{4}, has a density of 0.66 g/L. How many hydrogen atoms are in 2.41 L of the sample?

Watch Solution

Calculate the number of carbon atoms in 4.56 grams of ethanol (CH _{3}CH_{2}OH).

1. 2.53 × 10^{26} atoms

2. 1.19 × 10^{23} atoms

3. 1.79 × 10^{23} atoms

4. 5.49 × 10^{24} atoms

5. 5.97 × 10^{22} atoms

Watch Solution

How many moles of lithium phosphate are in 85.7 g of this substance?

1. 0.306578

2. 0.341986

3. 0.676199

4. 0.386893

5. 0.265989

6. 0.531978

7. 0.717652

8. 0.60452

9. 0.17272

10. 0.740105

Watch Solution

A quantity of N_{2} occupies 62.2 L at a particular temperature and pressure. Its density is 0.900 g/L. How many moles of N_{2} are in the container?

1. 10.1 mol

2. 12.4 mol

3. Cannot be determined

4. 2.00 mol

5. 34.6 mol

Watch Solution

How many oxygen atoms are there in 1.55 ng of Ca _{3}(PO_{4})_{2} ?

A) 3.01 x 10^{12}

B) 1.20 x 10^{13}

C) 3.01 x 10^{18}

D) 1.21 x 10^{16}

E) 2.41 x 10^{13}

Watch Solution

What mass of aluminum bromide will contain 6.3 x 10 ^{20} bromide ions ?

a) 93 mg

b) 31 mg

c) 9.3 mg

d) 27 mg

e) 273 mg

Watch Solution

What is the mass of 5.45 x 10 ^{-3} mol of glucose C_{6}H_{12}O_{6}?

A) 0.158 g

B) 982 mg

C) 3.03 x 10^{-5} g

D) 9.82 x 10^{2} g

E) 164 mg

Watch Solution

How many xenon atoms are contained in 2.36 moles of xenon?

Watch Solution

Calculate the molar mass for Mg(ClO_{4})_{2}.

A) 223.21 g/mol

B) 123.76 g/mol

C) 119.52 g/mol

D) 247.52 g/mol

E) 75.76 g/mol

Watch Solution

Precious metals are sometimes weighed in old-timey units like “troy ounces”, where 1 troy ounce = 31.1035 grams. A platinum coin is made that weighs 0.5003 troy ounces. The coin has a radius of 13.5 mm and a thickness of 1.28 mm. (Useful information: volume of a cylinder = (π *r*^{2})*h* where *r* is radius, and *h* is height or thickness)

a) What is its density, in g/cm^{3}?

b) How many atoms of platinum are in the coin?

Watch Solution

Phosphorus tribromide is a liquid with a density of 2.852 g/cm^{3}. A beaker contains 0.4875 moles of this compound.

a) What is the chemical formula of phosphorus tribromide?

b) What is the volume of liquid in milliliters (mL)?

c) How many molecules of phosphorus tribromide are in the beaker?

d) How many atoms of bromine are in the beaker?

Watch Solution

How many oxygen molecules are present in a 32.00 g sample of oxygen gas?

A. 1 oxygen molecule

B. 4.133 x 10^{24} oxygen molecules

C. 1.204 x 10^{24} oxygen molecules

D. 6.022 x 10^{23} oxygen molecules

E. 2.240 x 10^{25} oxygen molecules

Watch Solution

How many grams of gold contain 1.39 x 10 ^{23} atoms of gold?

a. 0.220 g

b. 0.231 g

c. 4.33 g

d. 45.5 g

e. 853 g

Watch Solution

An atom of an element weights 9.12 x 10^{-23} g. What is the atomic mass of this element in atomic mass units?

a. 45.0

b. 54.9

c. 55.8

d. 58.7

e. 63.5

Watch Solution

Determine the number of moles of silicon in 5.00 mg Si.

a. 1.78 x 10^{-4} mol

b. 2.40 x 10^{-4} mol

c. 0.140 mol

d. 5.62 mol

e. 5.62 x 10^{3} mol

Watch Solution

What is the average mass in grams of one atom of iron?

a. 55.85 g

b. 6.02 x 10^{-23} g

c. 9.28 x 10^{-23} g

d. 1.66 x 10^{-24} g

e. 55.85 x 10^{-25} g

Watch Solution

Which of the following samples contains the largest number of atoms?

a. 1 g Li

b. 1 g F_{2}

c. 1 g C

d. 1 g P_{4}

e. 1 g N_{2}

Watch Solution

How many atoms of carbon are there in 0.80 moles of C _{6}H_{4}Cl_{2}?

a. 3.9 x 10^{24}

b. 3.6 x 10^{24}

c. 2.9 x 10^{24}

d. 6.0 x 10^{23}

e. 4.8 x 10^{23}

Watch Solution

How many sodium atoms are in 6.0 g of Na _{3}N?

a. 1.3 x 10^{23} atoms

b. 3.6 x 10^{24} atoms

c. 1.217 atoms

d. 4.6 x 10^{22} atoms

e. 0.072 atoms

Watch Solution

How many sulfur atoms are present in 256 mg of Al _{2}(S_{2}O_{3})_{3}?

a. 3.95 x 10^{22}

b. 6

c. 7.90 x 10^{22}

d. 0.393

e. 2.37 x 1021

Watch Solution

The total number of atoms in one formula unit of Fe_{2}(SO_{4})_{3} , is

a. 5.

b. 14.

c. 15.

d. 17.

e. 19.

Watch Solution

You have 2.50 g of each of the following elements: Ca, Cu, Cs, C, and Cr. Which sample contains the largest number of atoms?

a. Ca

b. Cu

c. Cs

d. C

e. Cr

Watch Solution

An ionic compound has the formula MCl_{2}. The mass of 0.3011 mol of the compound is 62.69 grams. What is the identity of the metal?

a. Ni

b. Cu

c. Ba

d. Hg

e. Sn

Watch Solution

How many bromide ions are in 0.55 g of iron(III) bromide?

HINT: What does the Roman numeral mean?

a. 1.1 x 10^{21} ions

b. 3.4 x 10^{21} ions

c. 3.3 x 10^{23} ions

d. 9.9 x 10^{23} ions

e. 2.9 x 10^{26} ions

Watch Solution

There are currently 7.37 billion people in the world. If we distributed 1 mole of pennies to everyone evenly, how many dollars would each person get?

a). 8.17 Trillion Dollars

b). 817 Billion Dollars

c). 81.7 Thousand Dollars

d). 817 Million Dollars

e). 81.7 Trillion Dollars

Watch Solution

Calculate the oxygen atoms in 25.0g of CaCO_{3}

Watch Solution

What is the molecular weight of glucose, C_{6}H_{12}O_{6}

Watch Solution

A sample mercury has a volume of 0.50 mL and a mass of 6.765 g

a) What is the density of the material in mg/mL?

b) How many atoms are in this 0.50 mL sample of mercury?

Watch Solution

How many grams is a water molecule?

a. 2x10^{23 }g

b. 3x10^{23} g

c. 3x10^{-23} g

d. 8x10^{-23} g

e. 5x10^{-19} g

Watch Solution

Of the following: one atom of uranium (U), one molecule of benzene (C_{6 }H_{6}), one mole of hydrogen atoms, or 6.02 × 10^{20} oxygen molecules, which one weighs the most?

1. one mole of hydrogen atoms

2. 6.02 × 10^{20} oxygen molecules

3. one molecule of C_{6 }H_{6}

4. one atom of U

Watch Solution

How many moles are in 42.6 g of water?

1. 767 mol

2. 3.04 mol

3. 2.66 mol

4. 2.37 mol

Watch Solution

Each mole of Al(NO_{3 })_{3} contains how many moles of oxygen atoms?

1. 1 mol

2. 6 mol

3. 3 mol

4. 9 mol

5. 12 mol

Watch Solution

Calculate the number of phosphorus atoms in 0.5 g of phosphorus.

1. 1.31467e+22

2. 9.72106e+21

3. 1.45733e+24

4. 7.1168e+23

5. 2.91632e+22

6. 2.01787e+22

7. 9.38124e+23

8. 5.06803e+23

9. 1.10065e+22

10. 3.49958e+22

Watch Solution

Suppose we have 100 g of each of the following substances. Which sample contains the largest number of moles?

1. MgCO_{3}, formula weight 84.3

2. AgCl, formula weight 143.3

3. Impossible to tell, unless we know what reaction will take place with the substance.

4. HCl, formula weight 36.5

5. H_{2 }O, formula weight 18.0

Watch Solution

How many grams of P are contained in one mole of Mg _{3} (PO_{4 })_{2}

Watch Solution

How many grams of oxygen are in 12.4 moles Al _{2}(SO_{4})_{3}?

a. 2.38 x 10^{3} g O

b. 9.30 g O

c. 12 g O

d. 192 g O

Watch Solution

How many moles of sulfur are in 12.4 moles Al _{2}(SO_{4})_{3}?

a. 3

b. 12.4

c. 37.2

d. 32

Watch Solution

Determine the volume of hexane that contains 5.33 x 10 ^{22} molecules of hexane. The density of hexane is 0.6548 g/mL and its molar mass is 86.17 g/mol.

a. 8.59 mL

b.13.5 mL

c. 7.40 mL

d. 12.4 mL

e. 11.6 mL

Watch Solution

Phenylenediamine (pictured below) is mainly used as a component of engineering polymers and composites. It is also an ingredient in hair dyes and is occasionally used as a substitute for henna.

How many molecules are in a 2.00 g of phenylenediamine?

a. 1.30 x 10^{28}

b. 1.11 x 10^{22}

c. 3.59 x 10^{-20}

d. 3.07 x 10^{-24}

Watch Solution

Phenylenediamine (pictured below) is mainly used as a component of engineering polymers and composites. It is also an ingredient in hair dyes and is occasionally used as a substitute for henna.

What mass of phenylenediamine contains 45.0 g carbon?

a. 67.6 g

b. 45.0 g

c. 72.0 g

d. 100 g

Watch Solution

Stearic acid (C_{18}H_{36}O_{2}) is a fatty acid found in beef and butter.

a) What is the molecular mass of stearic acid? Give your answer in units of g/mol.

b) How many oxygen atoms are present in 1.000 g of stearic acid?

Watch Solution

What mass (in kg) does 5.84 moles of vanadium (V) have?

A) 0.352 kg

B) 0.297 kg

C) 0.820 kg

D) 287 kg

E) 2.97 x 10^{3 }kg

Watch Solution

What mass (in kg) does 5.84 moles of potassium (K) have?

A) 0.352kg

B) 0.228kg

C) 0.820kg

D) 0.280kg

E) 0.632kg

Watch Solution

A student uses a mass balance to dispense 2.05 g of sulfur. How many moles of sulfur is this?

A. 0.0639

B. 65.7

C. 0.0152

D. 15.6

Watch Solution

How many moles of hydrogen atoms are in 1.00 mole of C _{5}H_{8} molecules?

A) 0.25 mol H atoms

B) 1.00 mol H atoms

C) 5.00 mol H atoms

D) 8.00 mol H atoms

E) 16.00 mol H atoms

Watch Solution

How many atoms of nickel (Ni) are contained in 47.6 g of Ni?

A) 1.23 × 10^{23} Ni atoms

B) 2.87 × 10^{24} Ni atoms

C) 2.96 × 10^{23} Ni atoms

D) 4.88 × 10^{23} Ni atoms

E) 7.43 × 10^{23} Ni atoms

Watch Solution

What is the molar mass of aspartic acid, C_{4}O_{4}H_{7}N?

A) 43.03 g/mol

B) 70.56 g/mol

C) 133.11 g/mol

D) 197.11 g/mol

E) 206.33 g/mol

Watch Solution

What is the identity of substance X if 0.380 mol of X weighs 17.5 g?

A) NO_{2 }

B) N_{2}O

C) N_{2}O_{4}

D) NO_{3}

Watch Solution

How many oxygen atoms are there in 3.00 g of sodium dichromate, Na _{2}Cr_{2}O_{7}?

A) 9.85 × 10 ^{20} oxygen atoms

B) 0.0801 oxygen atoms

C) 6.90 × 10 ^{21} oxygen atoms

D) 4.83 × 10 ^{22} oxygen atoms

Watch Solution

What is the mass of a single chlorine molecule, Cl _{2}?

A) 35.45 g

B) 70.90 g

C) 5.887 × 10 ^{-23} g

D) 1.177 × 10 ^{-22} g

Watch Solution

What is the molar mass of calcium permanganate?

A) 199 g/mol

B) 278 g/mol

C) 216 g/mol

D) 159 g/mol

Watch Solution

How many moles of C_{3}H_{8 }contain 4.95 × 10 ^{24 }hydrogen atoms?

A) 3.09 moles C_{3}H_{8}

B) 6.58 moles C_{3}H_{8}

C) 1.03 moles C_{3}H_{8}

D) 9.73 moles C_{3}H_{8}

E) 8.22 moles C_{3}H_{8}

Watch Solution

How many moles of N_{2}O_{3} contain 2.55 × 10^{24} oxygen atoms?

A) 7.87 moles N_{2}O_{3}

B) 1.41 moles N_{2}O_{3}

C) 4.23 moles N_{2}O_{3}

D) 12.7 moles N_{2}O_{3}

E) 2.82 moles N_{2}O_{3}

Watch Solution

What is the mass of 9.44 × 10 ^{24} molecules of NO_{2}? The molar mass of NO_{2} is 46.01 g/mol.

A) 294 g

B) 341 g

C) 205 g

D) 685 g

E) 721 g

Watch Solution

What is the mass (in kg) of 6.89 × 10 ^{25} molecules of CO_{2}? The molar mass of CO_{2} is 44.01 g/mol.

A) 5.04 kg

B) 3.85 kg

C) 3.03 kg

D) 2.60 kg

E) 6.39 kg

Watch Solution

Calculate the molar mass of Ca _{3}(PO_{4})_{2}.

A) 215.21 g/mol

B) 246.18 g/mol

C) 279.21 g/mol

D) 87.05 g/mol

E) 310.18 g/mol

Watch Solution

How many C_{2}H_{4 } molecules are contained in 45.8 mg of C _{2}H_{4 }? The molar mass of C_{2}H_{4 } is 28.05 g/mol.

A) 2.71× 10 ^{20} C_{2}H_{4 }molecules

B) 9.83 × 10 ^{20} C_{2}H_{4 } molecules

C) 7.74 × 10^{ 26 } C_{2}H_{4 } molecules

D) 4.69 × 10^{ 23} C_{2}H_{4 }molecules

E) 3.69 × 10^{ 23} C_{2}H_{4 } molecules

Watch Solution

How many N_{2}O_{4 }molecules are contained in 76.3 g N _{2}O_{4}? The molar mass of N_{2}O_{4} is 92.02 g/mol.

A) 4.59 × 10 ^{25} N_{2}O_{4} molecules

B) 5.54 × 10 ^{25} N_{2}O_{4 }molecules

C) 7.26 × 10 ^{23} N_{2}O_{4} molecules

D) 1.38 × 10 ^{24 }N_{2}O_{4} molecules

E) 4.99 × 10 ^{23} N_{2}O_{4} molecules

Watch Solution

How many sodium ions are contained in 99.6 mg of Na_{2}SO_{3}? The molar mass of Na_{2}SO_{3} is 126.05 g/mol.

A) 4.76 × 10 ^{20} sodium ions

B) 2.10 × 10 ^{21} sodium ions

C) 1.52 × 10 ^{27} sodium ions

D) 1.05 × 10 ^{21} sodium ions

E) 9.52 × 10 ^{20} sodium ions

Watch Solution

Calculate the molar mass for Mg(ClO_{4})_{2}.

A) 247.52 g/mol

B) 119.52 g/mol

C) 123.76 g/mol

D) 223.21 g/mol

E) 75.76 g/mol

Watch Solution

Calculate the mass (in g) of 1.9 x 10 ^{24} atoms of Pb.

A) 2.4 × 10 ^{2} g

B) 6.5 × 10 ^{2} g

C) 3.2 × 10 ^{2} g

D) 1.5 × 10 ^{2} g

E) 3.9 × 10 ^{2 }g

Watch Solution

Calculate the mass (in kg) of 4.87 x 10 ^{25 }atoms of Zn.

A) 1.09 kg

B) 1.89 kg

C) 5.29 kg

D) 1.24 kg

E) 8.09 kg

Watch Solution

How many Li atoms are contained in 97.9 g of Li?

A) 8.49 × 10 ^{24} Li atoms

B) 5.90 × 10 ^{25} Li atoms

C) 4.27 × 10 ^{22} Li atoms

D) 4.18 × 10 ^{24} Li atoms

E) 7.09 × 1021 Li atoms

Watch Solution

How many iron atoms are contained in 354 g of iron?

A) 9.50 × 10 ^{22} Fe atoms

B) 3.82 × 10 ^{24} Fe atoms

C) 2.13 × 10 ^{26} Fe atoms

D) 4.69 × 10 ^{24} Fe atoms

E) 2.62 × 10^{25} Fe atoms

Watch Solution

How many xenon atoms are contained in 2.36 moles of xenon?

A) 1.87 × 10 ^{26} xenon atoms

B) 3.92 × 10 ^{24} xenon atoms

C) 1.42 × 10 ^{24} xenon atoms

D) 2.55 × 10 ^{23} xenon atoms

E) 7.91 × 10 ^{25} xenon atoms

Watch Solution

What is the mass (in kg) of 6.89 × 10 ^{25} molecules of CO_{2}? The molar mass of CO_{2} is 44.01 g/mol.

A) 2.60 kg

B) 6.39 kg

C) 5.04 kg

D) 3.03 kg

E) 3.85 kg

Watch Solution

A Freon leak in the air-conditioning system of an old car releases 25 g of CF _{2}Cl_{2}. How many molecules of Freon are emitted?

a. 1.5 x 10^{25}

b. 0.211

c. 1.2 x 10^{23}

d. 1.8 x 10^{27}

Watch Solution

What mass (in kg) does 5.84 moles of titanium (Ti) have?

a. 0.352 kg

b. 0.122 kg

c. 0.820 kg

d. 0.280 kg

e. 0.632 kg

Watch Solution

A chemical reaction requires 6.00 moles of Fe(NO_{3})_{3}. What mass of iron(III) nitrate is needed?

A) 24.3 g

B) 875 g

C) 40.3 g

D) 1.45 x 10^{3} g

E) 515 g

Watch Solution

If the molar mass of a substance is 44.01 g/mol, what is the mass of 1.05 x 10 ^{24} molecules of the substance?

A) 76.7 g

B) 1.74 g

C) 4.62 x 10^{25} g

D) 4.19 x 10^{–23} g

E) 25.2 g

Watch Solution

If 4.05 x 10^{23} molecules of a substance have a mass of 86.2 g, what is the molar mass of the substance?

A) 128 g/mol

B) 3.49 x 10^{25} g/mol

C) 2.13 x 10^{22} g/mol

D) 4.70 x 10^{21} g/mol

E) 58.0 g/mol

Watch Solution

How many oxygen atoms are present in 1.50 mol of Zn(NO _{3})_{2}?

A) 4.50 atoms

B) 9.00 atoms

C) 9.03 ´ 10^{23} atoms

D) 5.42 ´ 10^{24} atoms

E) 1.49 ´ 10^{–23} atoms

Watch Solution

How many chloride ions are present in 0.100 mol of MgCl _{2}?

A) 0.200 Cl^{–} ions

B) 6.02 ´ 10^{22} Cl^{–} ions

C) 1.20 ´ 10^{23} Cl^{–} ions

D) 3.32 ´ 10^{–25} Cl^{–} ions

E) 3.01 ´ 10^{24} Cl^{–} ions

Watch Solution

How many formula units are in 0.25 mole of Na _{2}O?

A) 4.5 x 10^{23}

B) 0.75

C) 1.5 x 10^{23}

D) 4.2 x 10^{–25}

E) 0.25

Watch Solution

How many C atoms are in 5.50 g of C?

A. 5.01 x 10^{22} C atoms

B. 3.31 x 10^{24} C atoms

C. 6.02 x 10^{23} C atoms

D. 2.76 x 10^{23} C atoms

E. 5.50 x 10^{23} C atoms

Watch Solution

Determine the number of moles of aluminum in 96.7 g of Al.

A. 0.279 mol

B. 3.58 mol

C. 7.43 mol

D. 4.21 mol

E. 6.02 x 10^{23} mol

Watch Solution

How many moles of PBr_{3} are contained in 3.68 × 10^{25} bromine atoms?

A) 61.1 moles PBr_{3}

B) 20.4 moles PBr_{3}

C) 16.4 moles PBr_{3}

D) 183 moles PBr_{3}

E) 49.1 moles PBr_{3}

Watch Solution

What is the mass (in kg) of 6.89 × 10 ^{25} molecules of CO_{2}? The molar mass of CO_{2} is 44.01 g/mol.

A) 3.85 kg

B) 5.04 kg

C) 2.60 kg

D) 3.03 kg

E) 6.39 kg

Watch Solution

A 20.0 g sample of an element contains 4.95 x 10^{23} atoms. Identify the element.

A) Cr

B) O

C) Mg

D) Fe

Watch Solution

What is the molar mass of aspartic acid, C _{4}O_{4}H_{7}N?

A) 43.03 g/mol

B) 70.02 g/mol

C) 86.91 g/mol

D) 133.11 g/mol

E) 197.98 g/mol

Watch Solution

How many grams of Cr are found in 1.00 × 10 ^{2} g of K _{2}Cr_{2}O_{7}?

A) 33.8 g

B) 24.3 g

C) 12.2 g

D) 48.6 g

E) 35.4 g

Watch Solution

How many iron atoms are contained in 354 g of iron?

A) 9.50 × 10^{22} Fe atoms

B) 2.13 × 10^{26} Fe atoms

C) 3.82 × 10^{24} Fe atoms

D) 2.62 × 10^{25} Fe atoms

E) 4.69 × 10^{24} Fe atoms

Watch Solution

How many moles of Kr are contained in 398 mg of Kr?

A) 4.75 × 10 ^{-3} moles Kr

B) 1.19 × 10 ^{-4} moles Kr

C) 2.99 × 10 ^{-3} moles Kr

D) 33.4 moles Kr

E) 2.11 × 10 ^{-4} moles Kr

Watch Solution

How many moles of Ar are in 5.22 X 10^{22} atoms of this noble gas?

Watch Solution

How many Na atoms are there in 1.50 mol Na?

a.1.50

b. 9.03 X´10^{23 }

c. 3.00

d. 2.49 X´10^{-24}

e. 345

Watch Solution

What is the mass (grams) of 4.91 x 10^{21} Pt atoms?

1 mol Pt = 195.08 g = 6.022 x 10^{23} atoms

Watch Solution

How many atoms of calcium are in 4.008g of calcium metal?

Watch Solution

How many moles of manganese atoms are in 19.36 g of manganese metal?

Watch Solution

What is the mass (g) of silicon represented by 0.250 moles of elemental silicon?

Watch Solution

How many molecules of N_{2}O_{4} are in 76.3 g N_{2}O_{4}? The molar mass of N_{2}O_{4} is 92.02 g/mol.

a. 5.54 x 10^{25} N_{2}O_{4} molecules

b. 7.26 x 10^{23} N_{2}O_{4} molecules

c. 1.38 x 10^{24} N_{2}O_{4} molecules

d. 4.59 x 10^{25} N_{2}O_{4} molecules

e. 4.99 x 10^{23} N_{2}O_{4} molecules

Watch Solution

Amavadin is a vanadium-containing compound found in three species of toxic mushrooms. The chemical formula for amavadin is VC_{12}H_{16}N_{2}O_{10} and has molar mass 398.94 g•mol^{-1}. If a mushroom contains 2.00 mg of amavadin, how many molecules are present?

a. 1.20 x 10^{23}

b. 4.80 x 10^{23}

c. 3.02 x 10^{21}

d. 3.02 x 10^{18}

Watch Solution

What mass (in kg) does 0.0822 moles of lead (Pb) have?

a. 0.397 kg

b. 17.0 kg

c. 2.52 kg

d. 0.0170 kg

e. 0.632 kg

Watch Solution

The Freons are a class of compounds containing carbon, chlorine, and fluorine. While they have many valuable uses, they have been shown to be responsible for depletion of the ozone in the upper atmosphere. In 1991, two replacement compounds for Freons went into production: HFC-134a (CH_{2}FCF_{3}) and HCFC-124 (CHClFCF_{3}). Calculate the molar masses of these two compounds.

Watch Solution

Calculate the mass (in kilograms) of chlorine in 25 kg of each chlorofluorocarbon (CFC).

d. CF_{3}Cl

Watch Solution

Calculate the mass (in kilograms) of chlorine in 25 kg of each chlorofluorocarbon (CFC).

c. C_{2}F_{3}Cl_{3}

Watch Solution

Calculate the mass (in kilograms) of chlorine in 25 kg of each chlorofluorocarbon (CFC).

b. CFCl_{3}

Watch Solution

Calculate the mass (in kilograms) of chlorine in 25 kg of each chlorofluorocarbon (CFC).

a. CF_{2}Cl_{2}

Watch Solution

Determine the number of moles of oxygen atoms in each sample:

a. 4.88 mol H_{2}O_{2}

b. 2.15 mol N_{2}O

c. 0.0237 mol H_{2}CO_{3}

d. 24.1 mol CO_{2}

Watch Solution

If 2.50 grams of an unknown compound contains 6.25 x 10 ^{19} molecules, what is its molecular mass?

Watch Solution

Which of the following amounts have the ** most** molecules?

a) 15.0 g N_{2}

b) 15.0 g Br_{2}

c) 15.0 g O_{2}

d) 15.0 g l_{2}

Watch Solution

Which of the following amounts would contain the ** least** atoms?

a) 10.0 g Sr

b) 10.0 g Br

c) 10.0 g Mg

d) 10.0 g Li

Watch Solution

How many atoms of oxygen are there in 53.2 g Al _{2}(SO_{4})_{3}?

a. 9.36 x 10^{22}

b. 3.75 x 10^{23}

c. 1.12 x 10^{24}

d. 2.81 x 10^{23}

Watch Solution

A 7.36-g sample of copper is contaminated with an additional 0.51 g of zinc. Suppose an atomic mass measurement was performed on this sample. What would be the measured atomic mass?

Watch Solution

What is the amount, in moles, of each elemental sample?

c. 26.1 g Ta

Watch Solution

What is the amount, in moles, of each elemental sample?

b. 3.55 g Zn

Watch Solution

What is the amount, in moles, of each elemental sample?

a. 11.8 g Ar

Watch Solution

How many moles of aluminum do 5.8 X 10^{24} aluminum atoms represent?

Watch Solution

How many sulfur atoms are there in 3.8 mol of sulfur?

Watch Solution

In Section 2.9, it was stated that 1 mol of sand grains would cover the state of Texas to several feet. Estimate how many feet by assuming that the sand grains are roughly cube-shaped, each one with an edge length of 0.10 mm. Texas has a land area of 268,601 square miles.

Watch Solution

A 67.2 g sample of a gold and palladium alloy contains 2.49 x 10 ^{23} atoms. What is the composition (by mass) of the alloy?

Watch Solution

Common brass is a copper and zinc alloy containing 37.0% zinc by mass and having a density of 8.48 g/cm^{3}. A fitting composed of common brass has a total volume of 112.5 cm^{3}. How many atoms (copper and zinc) does the fitting contain?

Watch Solution

A pure copper sphere has a radius of 0.935 in. How many copper atoms does it contain? [The volume of a sphere is (4/3)*πr *^{3 }and the density of copper is 8.96 g/ cm ^{3}.]

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A pure titanium cube has an edge length of 2.78 in. How many titanium atoms does it contain? Titanium has a density of 4.50 g/ cm^{3}.

Watch Solution

The mass of an average blueberry is 0.75 g and the mass of an automobile is 2.0 X 10^{3} kg. Find the number of automobiles whose total mass is the same as 1.0 mol blueberries.

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Consider the stack of pennies in the previous problem. How much money (in dollars) would this represent? If this money were equally distributed among the world's population of 6.5 billion people, how much would each person receive? Would each person be a millionaire? Billionaire? Trillionaire?

Watch Solution

A penny has a thickness of approximately 1.0 mm. If you stacked Avogadro's number of pennies one on top of the other on Earth's surface, how far would the stack extend (in km)? [For comparison, the sun is about 150 million km from Earth and the nearest star (Proxima Centauri) is about 40 trillion km from Earth.]

Watch Solution

An α particle, ^{4}H^{2+}, has a mass of 4.00151 amu. Find the value of its charge-to-mass ratio in C/kg.

Watch Solution

Using scanning tunneling microscopy, scientists at IBM wrote the initials of their company with 35 individual xenon atoms (as shown below). Calculate the total mass of these letters in grams.

Watch Solution

Calculate the average mass, in grams, of one platinum atom.

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How many helium atoms are there in a helium blimp containing 536 kg of helium?

Watch Solution

Calculate the mass, in kg, of each sample.

a. 7.55 x 10^{26} cadmium atoms

b. 8.15 x 10^{27} nickel atoms

c. 1.22 x 10^{27} manganese atoms

d. 5.48 x 10^{29} lithium atoms

Watch Solution

What is the mass of 4.91 x 10 ^{21} platinum atoms?

Watch Solution

How many silver atoms are there in 3.78 g of silver?

Watch Solution

What is the mass, in grams, of each elemental sample?

d. 1.3 mol W

Watch Solution

What is the mass, in grams, of each elemental sample?

c. 43.9 mol Xe

Watch Solution

What is the mass, in grams, of each elemental sample?

b. 0.0355 mol Ba

Watch Solution

What is the mass, in grams, of each elemental sample?

a. 2.3 x 10 ^{–3} mol Sb

Watch Solution

What is the amount, in moles, of each elemental sample?

d. 0.211 g Li

Watch Solution

How many moles of sodium ions (Na ^{+}) are in 56.0 g of sodium phosphate (Na _{3}PO_{4})?

A. 0.342 mol Na^{+}

B. 1.03 mol Na^{+}

C. 0.114 mol Na^{+}

D. 3.06 x 10^{3} mol Na^{+}

Watch Solution

A 2.000 g sample of an unknown metal, M, was completely burned in excess O _{2} to yield 0.02224 mol of the metal oxide, M_{2}O_{3}. What is the metal?

A. Y

B. Ca

C. Al

D. Sc

Watch Solution

A gold cylinder has a length of 6.25 cm and a radius of 1.25 cm. The density of gold is 19.3 g/cm^{3}. V_{cylinder} = π r ^{2 }l

How many gold atoms are contained in the gold cylinder?

A. 1.94 x 10 ^{-19} atoms

B. 1.81 x 10 ^{24} atoms

C. 1.92 x 10 ^{21} atoms

D. 9.85 x 10 ^{23} atoms

Watch Solution

The number of atoms in 9.0 g of aluminum is the same as the number of atoms in _____.

A. 8.1 g of magnesium

B. 9.0 g of magnesium

C. 12.1 g of magnesium

D. 18.0 g of magnesium

Watch Solution

Avogadro's number equals the number of

a) atoms in one mole of atoms.

b) molecules in one mole of O_{2}.

c) marbles in one mole of marbles.

d) all of the above.

Watch Solution

What mass of carbon is present in 1.4 x 10 ^{20} molecules of sucrose (C_{12}H_{22}O_{11})?

a) 1.7 x 10^{21} g

b) 2.0 x 10^{22} g

c) 3.3 x 10 ^{-2} g

d) 2.8 x 10^{-3} g

Watch Solution

How many atoms are in 1.50 g of Al?

a) 0.0556

b) 18.0

c) 3.35 x 10^{22}

d) 2.44 x 10^{25}

Watch Solution

What mass of carbon is present in 0.500 mol of sucrose (C _{12}H_{22}O_{11})?

a) 60.0 g

b) 72.0 g

c) 90.0 g

d) 120.0 g

Watch Solution

What mass of KClO_{3} will produce 48.0 g of oxygen gas, O_{2}, if the decomposition of KClO_{3} is complete?

a) 61.3 g

b) 74.5 g

c) 122.5 g

d) 245.0 g

Watch Solution

A single molecule of a certain compound has a mass of 3.4 x 10 ^{–22} g. Which value comes closest to the mass of a mole of this compound?

a) 50 g•mol^{–1}

b) 100 g•mol^{–1}

c) 150 g•mol^{–1}

d) 200 g•mol^{–1}

Watch Solution

The number of atoms in 9.0 g of aluminum is the same as the number of atoms in

a) 8.1 g of magnesium.

b) 9.0 g of magnesium.

c) 12.1 g of magnesium.

d) 18.0 g of magnesium.

Watch Solution

A 3.41 x 10^{–6} g sample of a compound is known to contain 4.67 x 10 ^{16} molecules. This compound is

a) CO_{2}

b) CH_{4}

c) NH_{3}

d) H_{2}O

Watch Solution

A sample of a compound of xenon and fluorine contains molecules of a single type; XeF* _{n }*, where

a) 2

b) 3

c) 4

d) 6

Watch Solution

What mass of the compound CrO_{3} (M = 100.0) contains 4.5 x 10 ^{23} oxygen atoms?

a) 2.25 g

b) 12.0 g

c) 25.0 g

d) 75.0 g

Watch Solution

How many grams of P is contained in one mole of Mg _{3}(PO_{4})_{2}?

Watch Solution

If the mass of 2.51 x 10 ^{-3} moles of compound A is 0.452 g, then what is the molar mass?

Watch Solution

How many sodium ions are contained in 99.6 mg of Na _{2}SO_{3} ?

a) 1.05 X 10^{21}

b) 1.52 X 10^{27}

c) 2.10 X 10^{21}

d) 9.52 X 10^{20}

Watch Solution

How many moles of C_{3}H_{8} contain 9.25 × 10^{24} molecules of C_{3}H_{8}?

A) 65.1 moles C_{3}H_{8}

B) 28.6 moles C_{3}H_{8}

C) 34.9 moles C_{3}H_{8}

D) 46.2 moles C_{3}H_{8}

E) 15.4 moles C_{3}H_{8}

Watch Solution

How many moles of N _{2}O_{3} contain 2.55 × 10 ^{24} oxygen atoms?

A) 1.41 moles N_{2}O_{3}

B) 4.23 moles N_{2}O_{3}

C) 12.7 moles N_{2}O_{3}

D) 7.87 moles N_{2}O_{3}

E) 2.82 moles N_{2}O_{3}

Watch Solution

How many sodium ions are contained in 99.6 mg of Na _{2}SO_{3}? The molar mass of Na_{2}SO_{3} is 126.05 g/mol.

A) 1.52 × 10^{27} sodium ions

B) 4.76 × 10^{20} sodium ions

C) 2.10 × 10^{21} sodium ions

D) 1.05 × 10^{21} sodium ions

E) 9.52 × 10^{20} sodium ions

Watch Solution

How many atoms of oxygen are contained in 47.6 g of Al _{2}(CO_{3})_{3}? The molar mass of Al_{2}(CO_{3})_{3} is 233.99 g/mol.

A) 1.23 × 10^{23} O atoms

B) 2.96 × 10^{24} O atoms

C) 2.87 × 10^{25} O atoms

D) 1.10 × 10^{24} O atoms

E) 3.19 × 10^{24} O atoms

Watch Solution

How many C_{2}H_{4} molecules are contained in 45.8 mg of C _{2}H_{4}? The molar mass of C_{2}H_{4} is 28.05 g/mol.

A) 9.83 × 10^{20} C_{2}H_{4} molecules

B) 7.74 × 10^{26} C_{2}H_{4} molecules

C) 2.71× 10^{20} C_{2}H_{4} molecules

D) 3.69 × 10^{23} C_{2}H_{4} molecules

E) 4.69 × 10^{23} C_{2}H_{4} molecules

Watch Solution

How many N_{2}O_{4} molecules are contained in 76.3 g N _{2}O_{4}? The molar mass of N _{2}O_{4} is 92.02 g/mol.

A) 5.54 × 10^{25} N_{2}O_{4} molecules

B) 7.26 × 10^{23} N_{2}O_{4} molecules

C) 1.38 × 10^{24} N_{2}O_{4} molecules

D) 4.59 × 10^{25} N_{2}O_{4} molecules

E) 4.99 × 10^{23} N_{2}O_{4} molecules

Watch Solution

How many iron atoms are contained in 354 g of iron?

A) 2.62 × 10^{25} Fe atoms

B) 2.13 × 10^{26} Fe atoms

C) 4.69 × 10^{24} Fe atoms

D) 3.82 × 10^{24} Fe atoms

E) 9.50 × 10^{22} Fe atoms

Watch Solution

How many Li atoms are contained in 97.9 g of Li?

A) 5.90 × 10^{25} Li atoms

B) 7.09 × 10^{21} Li atoms

C) 8.49 × 10^{24} Li atoms

D) 4.27 × 10^{22} Li atoms

E) 4.18 × 10^{24} Li atoms

Watch Solution

How many argon atoms are contained in 7.66 x 10 ^{5} mol of argon?

A) 4.61 × 10^{29} Ar atoms

B) 1.84 × 10^{28} Ar atoms

C) 1.15 × 10^{28} Ar atoms

D) 7.86 × 10^{20} Ar atoms

E) 3.24 × 10^{26} Ar atoms

Watch Solution

A 0.370 mol sample of a metal oxide (M _{2}O_{3}) weighs 55.4 g. How many grams of M are in the sample, and what element is represented by the symbol M?

a) 75.28 g/mol; Arsenic

b) 101.7 g; Ruthenium

c) 37.6 g; Vanadium

d) 17.8 g; Metalium

e) 41.3 g; Iron

Watch Solution

How many moles are in 26.7 grams of calcium nitrate?

Watch Solution

What mass of carbon is present in 0.500 mol of sucrose (C_{12}H_{22}O_{11})?

Molar mass: C_{12}H_{22}O_{11} = 342 g/mol

A. 60.0 g

B. 72.0 g

C. 90.0 g

D. 120 g

Watch Solution

A 1.000-g sample of a metal chloride, MCl _{2}, is dissolved in water and treated with excess aqueous silver nitrate. After drying, the silver chloride that formed weighed 1.286 g. Calculate the mass of M.

a) 222.8 g b) 76.00g c) 152.0 g d) 304.0 g e) none of these

Watch Solution

What is the atomic weight of an element, X, if 1.00g of X combines with 0.66 g of oxygen to form a compound XO_{3}?

A. 24

B. 67

C. 73

D. 100

E. 146

Watch Solution

What is A, if 64.0 g of A combines exactly with 142 g of Cl to give the compound ACl _{2}?

A. Br

B. Mg

C. Ca

D. S

E. Ba

Watch Solution

What is the mass of one molecule of C_{8}H_{18} (octane) in grams?

A. 114

B. 1.9 x 10^{-22}

C. 26

D. 6.9 x 10^{-21}

E. 3.8 x 10^{-22}

Watch Solution

A compound has a formula of Y_{2}O_{5}. If 2.8 g of Y combines with 8.0 g of oxygen, what is the atomic weight of Y?

A. 10

B. 12

C. 14

D. 16

E. 18

Watch Solution

Which of the following contains most hydrogen atoms in one gram of sample?

A. HClO_{4}

B. HClO_{3}

C. HClO_{2}

D. HClO

E. HCl

Watch Solution

Which contains the largest number of carbon atoms?

A. 0.10 mol of carbon atoms

B. 1.2 g carbon

C. 0.10 mol of CH_{4}

D. 1.6 g of CH_{4}

E. All are the same

Watch Solution

A normal breath takes in about 1.0 L of air. Assuming that air has an average molar mass of 28.8 g/mol, and that its density is 0.97 g/L, how many molecules of air do you take in with each breath?

A. 1.7 x 10^{25}

B. 1.8 x 10^{25}

C. 2.0 x 10^{22}

D. 2.2 x 10^{22}

E. 5.8 x 10^{23}

Watch Solution

How many moles are in 25 mg of O _{2}? (Atomic mass of O = 16.00 g/mol)

A) 7.8 ×10^{−4}

B) 1.6 ×10^{−3 }

C) 0.40

D) 0.80

E) 800

Watch Solution

For a 90.0 g sample of glucose (C_{6}H_{12}O_{6)} and a 171.1 g sample of sucrose (C_{12}H_{22}O_{11}), which statement is true?

a. The sample of glucose has more moles than the sample of sucrose.

b. The sample of sucrose has more moles than the sample of glucose.

c. The samples have the same number of moles.

d. 1 mol of glucose has greater molecular mass than 1 mol of sucrose.

e. 1 mol of glucose has more C atoms in comparison to 1 mol of sucrose.

Watch Solution

We have a 1.3 x 10^{22} lead atoms and the same number of gold atoms. Which statement is true regarding the mass of these samples?

a. The mass of both of the samples is the same

b. The mass of the lead sample is greater than the mass of the gold sample.

c. The mass of the gold sample is greater than the mass of the lead sample.

d. The mass of the gold sample is 4.5 g.

e. The mass of the lead sample is 4.3 g.

Watch Solution

The definition of the mole gives the relationship between:

a. mass and the atomic number.

b. mass and number of atoms.

c. mass and weight.

d. the masses of the different isotopes of an atom.

e. the isotopes of an atom and the number of atoms.

Watch Solution

Which statement below is true?

a. The number of Ni atoms in 100 moles of Ni (s) is the same as the number of Ni atoms in 100 moles of nickel (II) chloride, NiCl_{2}.

b. One moles of NH _{3} weighs more than one mole of H _{2}O.

c. There are equal numbers of nitrogen atoms in one mole of NH _{3} and one mole of N _{2}.

d. The number of Cu atoms in 100 grams of Cu (s) is the same as the number of Cu atoms in 100 grams of copper (II) oxide, CuO.

e. There are more hydrogen atoms in 2 moles of NH _{3} than in 2 moles of CH _{4}.

Watch Solution

One molecule of a compound weighs 2.03 x 10 ^{-22} grams. Calculate the molar mass of this molecule.

a. 3.37 x 10^{-46} g/mol

b. 3.36 x 10^{-23} g/mol

c. 1.23 x 10^{-21} g/mol

d. 1.22 x 10 ^{2} g/mol

e. 1.21 x 10^{24} g/mol

Watch Solution

What is the molar mass of calcium phosphate, Ca _{3}(PO_{4})_{2}?

a. 87.05 g/mol

b. 215.21 g/mol

c. 278.18 g/mol

d. 279.21 g/mol

e. 310.18 g/mol

Watch Solution

How many moles of methanol are present in a 150.0 gram sample of methanol, CH_{3}OH?

a. 7.776 x 10 ^{-24 }moles

b. 4.681 moles

c. 5.172 moles

d. 4806 moles

e. 2.818 x 10 ^{24} moles

Watch Solution

What mass (in kg) does 5.84 moles of Titanium (Ti) have?

a. 0.352 kg

b. 0.122 kg

c. 0.820 kg

d. 0.280 kg

e. 0.632 kg

Watch Solution

If 2.50 grams of an unknown compound contains 6.25 x 10^{19} molecules, what is its molecular mass?

Watch Solution

Which of the following equals the number of hydrogen atoms in 40 grams of methane?

a. 1.5 x 10 ^{24}

b. 2.4 x 10 ^{24}

c. 6.0 x 10 ^{24}

d. 6.022 x 10 ^{23}

Watch Solution

What is the mass of one molecule of C _{8}H_{18} (octane) in grams?

A. 114

B. 1.9 x 10^{-22 }

C. 26

D. 6.9 x 10^{-21 }

E. 3.8 x 10^{-22}

Watch Solution

A single atom of a certain element has a mass of 3.352 x 10 ^{-23 }g. The element is

a. Ne

b. Co

c. Al

d. Br

e. Ti

Watch Solution

What is the mass of 1.3 x 10 ^{13} moles of N_{2 }in pg?

a. 3.64 x 10^{14}

b. 1.82 x 10^{14}

c. 1.82 x 10^{26}

d. 3.64 x 10^{26}

e. none of the given answers is even close to being correct

Watch Solution

What is the weight of O in 742.0 g of citronella oil that has the chemical formula C_{10}H_{18}O?

a. 19.31

b. 18.52

c. 77.10

d. 115.5

e. 231.3

Watch Solution

How many oxygen atoms are in a 125 mg sample of aspirin? The molar mass of aspirin is 180.15 g/mol and its molecular formula is C_{9}H_{8}O_{4}.

a) 4.18 × 10^{23 }

b) 4.18 × 10^{20 }

c) 1.67 × 10^{21}

d) 1.36 × 10^{25}

e) 8.68 × 10^{23}

Watch Solution

How many Cl^{–} ions are there in 15.6 g of MgCl _{2}?

Watch Solution

How many Cl atoms are there in 27.3 grams of magnesium chloride?

Watch Solution

Identify the correct statement regarding the mole.

a) A mole of oxygen gas contains 6.02 x 10 ^{23} atoms.

b) A mole of chlorine gas contains 2 x 6.02 x 10 ^{23} molecules.

c) A mole of carbon dioxide contains two moles of oxygen atoms.

d) A mole of ammonia gas (NH _{3}) has a mass of 34.0 g.

e) A mole consists of the number of particles in exactly 12 g of naturally occurring carbon.

Watch Solution

A 1.000-g sample of a metal chloride, MCl _{2}, is dissolved in water and treated with excess aqueous silver nitrate. After drying, the silver chloride that formed weighed 1.286 g. Calculate the atomic mass of M.

a) 222.8 g

b) 76.00 g

c) 152.0 g

d) 304.0 g

e) none of these

Watch Solution

How many Cl atoms are there in 27.3 grams of magnesium chloride?

Watch Solution