Mass & Conversions

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

The Mole 

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. 

Mass Conversions

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

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Video Transcript

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 

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Video Transcript

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 1028 nitrogen atoms.  

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Concept: Molecules to Moles to Grams

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Video Transcript

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, CO2, are found in 75.0 g CO2.

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Mass Conversion Calculations

Problem: If the density of water is 1.00 g/mL at 25oC. Calculate the number of water molecules found in 1.50 x 103 µL of water.

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Problem: Calculate the number of oxygen atoms found in 783.9 g in copper (II) sulfate pentahydrate, CuSO4 x 5 H2O.

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Problem: The density of the sun is 1.41 g/cm3 and its volume is 1.41 x 1027 m3. How many hydrogen molecules are in the sun if we assume all the mass is hydrogen gas?

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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/cm3. ( V = π x r2 x h )

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Mass & Conversions Additional Practice Problems

The molecular weight of ethanol (C2H5OH) is 46.1 and the density of absolute (100%) ethanol = 0.79 g/mL.

During a romantic candlelight dinner a 75 kg person drinks a bottle (750 mL) of wine in the space of 3 hours. Ethanol is metabolized at a constant rate of 120 mg per hour per kg body weight, regardless of its concentration. A 75 kg person contains about 40 L of ‘water’. Ignore the metabolism, and assume the water content of the person remains constant.

a)What is their blood alcohol content (mg/100 mL blood) at the end of the dinner?

 

 

 

b)How long will it take for their blood alcohol level to fall below the legal limit of 50mg of ethanol per 100mL of blood (0.05%)?

Watch Solution

The molecular weight of ethanol (C2H5OH) is 46.1 and the density of absolute (100%) ethanol = 0.79 g/mL. The legal limit for a driver’s blood alcohol is 50 mg of ethanol per 100 mL of blood (referred to as a blood alcohol content (BAC) of 0.05%). And a bottle of wine is 14% ethanol by volume. 

How much wine (standard serving size = 100 mL) could a 75 kg person drink and remain under the legal limit? The blood alcohol content will be equivalent to the alcohol content in the total ‘water’ component of the human body. A 75 kg person contains about 40 L of ‘water’. Ignore the metabolism, and assume the water content of the person remains constant.

Watch Solution

What is the molar mass of aspirin, C9H8O4?

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Calculate the molar mass of potassium hydroxide (KOH).

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Calculate the molar mass of Cl 2 if 1.27 x 1022 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 KHC8H4O4 .

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The molar mass of HNO3 is 63.01g/mol,  perform each of the following conversions

i) convert 13.9 g of HNO3 to moles and

ii) convert 2.507 moles of HNO3 to grams

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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 3CO2H. The atomic masses for each element are C = 12.0106 ± 0.0010, H = 1.00798 ± 0.00014, and O = 15.9990 ± 0.0008

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What is molar mass of Na 2CO3?

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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 1023 molecules of CO2

B) 2.74 x 1023 molecules of CO2

C) 5.30 x 1026 molecules of CO2 

D) 1.46 x 10-21 molecules of CO

E) 7.55 x 10-25  molecules of CO2

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The empirical formula of a chemical compound is C3H8O3. Its approximate molar mass of 94 g/mol was found by experiment. Calculate its exact molar mass.

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Consider the compound C2H4O2. How many grams of oxygen are in 3.0 grams of it?

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You drank 100.0 g of water. This quantity of water contains hydrogen that is equivalent to (x) moles of hydrogen (H2).

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You ate 5.0g of sugar (C6H12O6). This quantity of sugar contains oxygen that is equivalent to how many moles of ozone (O3)?

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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? 

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

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How many moles of carbon atoms are present in a piece of diamond which has a volume of 1.00 cm3? The density of diamond is 3.53 g/cm3.

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Calculate the average mass, in grams, of an O2 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

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Determine the mass (g) of solute required to form 275 mL of a 0.4230 M KClO  3 solution.

a. 1.97

b. 4.21

c. 14.3

d. 12.2

e. 19.6

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6.02 x 1021 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

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

(A) 2.01 x 1023 nitrogen atoms

(B) 6.02 x 1023 nitrogen atoms

(C) 1.20 x 1024 nitrogen atoms

(D) 1.81 x 1024 nitrogen atoms

(E) 3.61 x 1024 nitrogen atoms

Watch Solution

32.0 grams of the element oxygen:

(A) contain 6.02 x 1023 atoms of oxygen

(B) contain 1.204 x 1024 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

Consider the reaction of hydrogen gas (H2) and oxygen gas (O2) to form water. How many molecules of water will be made by the reaction of 12.0 g of O2 gas?

(A) 1.13 x 1023 molecules

(B) 2.26 x 1023 molecules

(C) 4.52 x 1023 molecules

(D) 2.26 x 1024 molecules

(E) 4.52 x 1024 molecules

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 1023 mol

Watch Solution

What is the mass of 4.50 x 1022 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 2HBrClF3?

(A) 1.81 x 1023

(B) 6.02 x 1023

(C) 6.69 x 1021

(D) 6.03 x 1022

(E) 2.23 x 1023

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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 1024 g

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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 1048 moles

Watch Solution

Calculate the number of carbon atoms in 4.56 grams of ethanol (CH 3CH2OH).

1. 2.53 × 1026 atoms

2. 1.19 × 1023 atoms

3. 1.79 × 1023 atoms

4. 5.49 × 1024 atoms

5. 5.97 × 1022 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

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A quantity of N2 occupies 62.2 L at a particular temperature and pressure. Its density is 0.900 g/L. How many moles of N2 are in the container?

1. 10.1 mol

2. 12.4 mol

3. Cannot be determined

4. 2.00 mol 

5. 34.6 mol

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How many grams of chlorine are there in 22.7 g of zinc chloride?

A) 5.90 g

B) 0.17 g

C) 10.9 g

D) 14.7 g

E) 11.81 g

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How many oxygen atoms are there in 1.55 ng of Ca 3(PO4)2 ?

A) 3.01 x 1012

B) 1.20 x 1013

C) 3.01 x 1018

D) 1.21 x 1016

E) 2.41 x 1013

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

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Which of the following represents the LARGEST mass?

a) 1.20 x 107 mg

b) 120 kg

c) 12.0 ton

d) 1200 lb

e) 1.20 metric ton

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What is the mass of 5.45 x 10 -3 mol of glucose C6H12O6?

A) 0.158 g

B) 982 mg

C) 3.03 x 10-5 g

D) 9.82 x 102

E) 164 mg

Watch Solution

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

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Calculate the molar mass for Mg(ClO4)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

Phosphorus tribromide is a liquid with a density of 2.852 g/cm3.  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?

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On the planet Tatooine, the unit of length is the zither which is defined by the relationship 7.50 cm = 1 zither. A distance of 100 meters would be _________ zithers.

a. 133

b. 266

c. 750

d. 1.33 X 103

e. 7.5 X 104

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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

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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 103 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 F2

c. 1 g C

d. 1 g P4

e. 1 g N2

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How many atoms of carbon are there in 0.80 moles of C 6H4Cl2?

a. 3.9 x 1024

b. 3.6 x 1024

c. 2.9 x 1024

d. 6.0 x 1023

e. 4.8 x 1023

Watch Solution

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

a. 1.3 x 1023 atoms

b. 3.6 x 1024 atoms

c. 1.217 atoms

d. 4.6 x 1022 atoms

e. 0.072 atoms

Watch Solution

How many sulfur atoms are present in 256 mg of Al 2(S2O3)3?

a. 3.95 x 1022

b. 6

c. 7.90 x 1022

d. 0.393

e. 2.37 x 1021

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 MCl2. 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 1021 ions

b. 3.4 x 1021 ions

c. 3.3 x 1023 ions

d. 9.9 x 1023 ions

e. 2.9 x 1026 ions

Watch Solution

One molecule of a compound weighs 2.03 x l0 22 g. The compound is:
a) SO

b)SiO4 

c)Al2O3 

d)PdO

e) none of these 

 

 

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What is the molecular weight of glucose, C6H12O6

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Of the following: one atom of uranium (U), one molecule of benzene (CH6), one mole of hydrogen atoms, or 6.02 × 1020 oxygen molecules, which one weighs the most?

1. one mole of hydrogen atoms

2. 6.02 × 1020 oxygen molecules

3. one molecule of CH6

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

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. MgCO3, 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. HO, formula weight 18.0

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 1028

b. 1.11 x 1022

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 (C18H36O2) 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 10kg

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

A) 1.23 × 1023 Ni atoms

B) 2.87 × 1024 Ni atoms

C) 2.96 × 1023 Ni atoms

D) 4.88 × 1023 Ni atoms

E) 7.43 × 1023 Ni atoms

Watch Solution

What is the molar mass of aspartic acid, C4OH7N?

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) NO2

B) N2O

C) N2O4

D) NO3

Watch Solution

How many oxygen atoms are there in 3.00 g of sodium dichromate, Na  2Cr2O7?

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

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What is the molar mass of calcium permanganate?

A) 199 g/mol

B) 278 g/mol

C) 216 g/mol

D) 159 g/mol

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How many moles of C3H8 contain 4.95 × 10 24 hydrogen atoms?

A) 3.09 moles C3H8

B) 6.58 moles C3H8

C) 1.03 moles C3H8

D) 9.73 moles C3H8

E) 8.22 moles C3H8

Watch Solution

How many moles of N2O3 contain 2.55 × 1024 oxygen atoms?

A) 7.87 moles N2O3 

B) 1.41 moles N2O3 

C) 4.23 moles N2O3 

D) 12.7 moles N2O3 

E) 2.82 moles N2O3 

Watch Solution

What is the mass of 9.44 × 10 24 molecules of NO2? The molar mass of NO2 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 CO2? The molar mass of CO2 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(PO4)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  C2H molecules are contained in 45.8 mg of  C 2H? The molar mass of  C2H is 28.05 g/mol.

A) 2.71× 10 20 C2H4 molecules

B) 9.83 × 10 20  C2H molecules

C) 7.74 × 10 26  C2H molecules

D) 4.69 × 10 23  C2Hmolecules

E) 3.69 × 10 23  C2H molecules

Watch Solution

How many N2O4 molecules are contained in 76.3 g N 2O4? The molar mass of N2O4 is 92.02 g/mol.

A) 4.59 × 10 25 N2O4 molecules

B) 5.54 × 10 25 N2O4 molecules

C) 7.26 × 10 23 N2O4 molecules

D) 1.38 × 10 24 N2O4 molecules

E) 4.99 × 10 23 N2O4 molecules

Watch Solution

How many sodium ions are contained in 99.6 mg of Na2SO3? The molar mass of Na2SO3 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(ClO4)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 × 1025 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 CO2? The molar mass of CO2 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

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(NO3)3. What mass of iron(III) nitrate is needed?

A)  24.3 g   

B)  875 g   

C)  40.3 g               

D)  1.45 x 103 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 1025 g   

D)  4.19 x 10–23 g   

E)  25.2 g

Watch Solution

If 4.05 x 1023 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 1025 g/mol                                   

C)  2.13 x 1022 g/mol

D)  4.70 x 1021 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 ´ 1023 atoms

D)  5.42 ´ 1024 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 ´ 1022 Cl ions

C)  1.20 ´ 1023 Cl ions

D)  3.32 ´ 10–25 Cl ions

E)  3.01 ´ 1024 Cl ions

Watch Solution

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

A)  4.5 x 1023   

B)  0.75                 

C)  1.5 x 1023   

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 1022 C atoms

B. 3.31 x 1024 C atoms

C. 6.02 x 1023 C atoms

D. 2.76 x 1023 C atoms

E. 5.50 x 1023 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 1023 mol

Watch Solution

How many moles of PBr3 are contained in 3.68 × 1025 bromine atoms?

A) 61.1 moles PBr3
B) 20.4 moles PBr3
C) 16.4 moles PBr3
D) 183 moles PBr3
E) 49.1 moles PBr3

Watch Solution

What is the mass (in kg) of 6.89 × 10 25 molecules of CO2? The molar mass of CO2 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 1023 atoms. Identify the element.

A) Cr

B) O

C) Mg

D) Fe

Watch Solution

What is the molar mass of aspartic acid, C 4O4H7N? 

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 2Cr2O7?

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 × 1022 Fe atoms

B) 2.13 × 1026 Fe atoms

C) 3.82 × 1024 Fe atoms

D) 2.62 × 1025 Fe atoms

E) 4.69 × 1024 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 1022 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´1023  

c. 3.00  

d. 2.49 X´10-24   

e. 345

Watch Solution

What is the mass (grams) of 4.91 x 1021 Pt    atoms?

   1 mol Pt = 195.08 g = 6.022 x 1023 atoms

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

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

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

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How many molecules of N2O4 are in 76.3 g N2O4? The molar mass of N2O4 is 92.02 g/mol.

a. 5.54 x 1025 N2O4 molecules

b. 7.26 x 1023 N2O4 molecules

c. 1.38 x 1024 N2O4 molecules

d. 4.59 x 1025 N2O4 molecules

e. 4.99 x 1023 N2O4 molecules

Watch Solution

The ebola virus is structured like a long filament that ranges from 974 to 1086 nm in length. If length of a virus filament is found to be 1046 nm, what would the the length be in cm?

a. 1.046 x 1010 cm

b. 1.046 x 10 -4 cm

c. 1.046 x 1014 cm

d. 1.046 x 10 -8 cm

e. 1.046 x 10-3 cm

Watch Solution

Amavadin is a vanadium-containing compound found in three species of toxic mushrooms. The chemical formula for amavadin is VC12H16N2O10 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 1023

b. 4.80 x 1023

c. 3.02 x 1021

d. 3.02 x 1018

 

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

In the chemical reaction N2 + 3 Mg → Mg 3N2 if you begin with 1.35 moles of Mg, how many moles of N2 are required to react all of the Mg?

A. 0.45              

B. 1.01          

C. 1.35            

D. 1.80            

E. 4.05

 

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 N2

b) 15.0 g Br2

c) 15.0 g O2

d) 15.0 g l2

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(SO4)3?      

a. 9.36 x 1022

b. 3.75 x 1023

c. 1.12 x 1024

d. 2.81 x 1023

Watch Solution

How many moles of sodium ions (Na +) are in 56.0 g of sodium phosphate (Na 3PO4)?

A. 0.342 mol Na+

B. 1.03 mol Na+

C. 0.114 mol Na+

D. 3.06 x 103 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, M2O3. What is the metal?

A. Y

B. Ca

C. Al

D. Sc

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

What mass of the compound CrO3 (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

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  2SO3 ?

a) 1.05 X 1021

b) 1.52 X 1027

c) 2.10 X 1021

d) 9.52 X 1020

 

Watch Solution

How many moles of C3H8 contain 9.25 × 1024 molecules of C3H8?

A) 65.1 moles C3H8

B) 28.6 moles C3H8

C) 34.9 moles C3H8

D) 46.2 moles C3H8

E) 15.4 moles C3H8

Watch Solution

How many sodium ions are contained in 99.6 mg of Na 2SO3? The molar mass of Na2SO3 is 126.05 g/mol.

A) 1.52 × 1027 sodium ions

B) 4.76 × 1020 sodium ions

C) 2.10 × 1021 sodium ions

D) 1.05 × 1021 sodium ions

E) 9.52 × 1020 sodium ions

Watch Solution

How many atoms of oxygen are contained in 47.6 g of Al 2(CO3)3? The molar mass of Al2(CO3)3 is 233.99 g/mol.

A) 1.23 × 1023 O atoms

B) 2.96 × 1024 O atoms

C) 2.87 × 1025 O atoms

D) 1.10 × 1024 O atoms

E) 3.19 × 1024 O atoms

Watch Solution

How many C2H4 molecules are contained in 45.8 mg of C 2H4? The molar mass of C2H4 is 28.05 g/mol.

A) 9.83 × 1020 C2H4 molecules

B) 7.74 × 1026 C2H4 molecules

C) 2.71× 1020 C2H4 molecules

D) 3.69 × 1023 C2H4 molecules

E) 4.69 × 1023 C2H4 molecules

Watch Solution

How many N2O4 molecules are contained in 76.3 g N 2O4? The molar mass of N 2O4 is 92.02 g/mol.

A) 5.54 × 1025 N2O4 molecules

B) 7.26 × 1023 N2O4 molecules

C) 1.38 × 1024 N2O4 molecules

D) 4.59 × 1025 N2O4 molecules

E) 4.99 × 1023 N2O4 molecules

Watch Solution

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

A) 2.62 × 1025 Fe atoms

B) 2.13 × 1026 Fe atoms

C) 4.69 × 1024 Fe atoms

D) 3.82 × 1024 Fe atoms

E) 9.50 × 1022 Fe atoms

Watch Solution

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

A) 5.90 × 1025 Li atoms

B) 7.09 × 1021 Li atoms

C) 8.49 × 1024 Li atoms

D) 4.27 × 1022 Li atoms

E) 4.18 × 1024 Li atoms

Watch Solution

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

A) 4.61 × 1029 Ar atoms

B) 1.84 × 1028 Ar atoms

C) 1.15 × 1028 Ar atoms

D) 7.86 × 1020 Ar atoms

E) 3.24 × 1026 Ar atoms

Watch Solution

How many cm3 are contained in 3.77 × 104 mm3?

A) 3.77 × 104 cm3

B) 3.77 × 101 cm3

C) 3.77 × 10-10 cm3

D) 3.77 × 1020 cm3

E) 3.77 × 106 cm3

Watch Solution

A 0.370 mol sample of a metal oxide (M 2O3) 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 (C12H22O11)?

Molar mass: C12H22O11 = 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 XO3?

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 C8H18 (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 Y2O5. 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. HClO4

B. HClO3

C. HClO2

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 CH4

D. 1.6 g of CH4

E. All are the same

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 (C6H12O6) and a 171.1 g sample of sucrose (C12H22O11), 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 1022 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

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 1024 g/mol

Watch Solution

What is the molar mass of calcium phosphate, Ca 3(PO4)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, CH3OH?

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 1019 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 8H18 (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 N2  in pg?

a. 3.64 x 1014

b. 1.82 x 1014

c. 1.82 x 1026

d. 3.64 x 1026

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 C10H18O?

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 C9H8O4.

 

a) 4.18 × 1023

b) 4.18 × 1020

c) 1.67 × 1021

d) 1.36 × 1025

e) 8.68 × 1023

Watch Solution

A piece of metal was placed in a beaker, heated, and reacted with oxygen, thereby becoming a metal oxide. During this process, depending on reaction conditions, the metal’s oxidation state could become either M2+ or M3+. Consider the mass of the metal oxide.

 

a) The mass of the metal oxide is the same as the mass of the initial metal

b) The mass of the metal oxide is greatest if the metal becomes M 3+

c) The mass of the metal oxide is greatest if the metal becomes M 2+

d) The mass of the metal oxide is greatest if O 2(g) is the limiting reactant. 

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