Ch.12 - SolutionsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

The molarity of a solution is related to the amount of solute dissolved within a solvent. 

Molarity

Concept #1: Molarity is the concentration of a solution represented as moles of solute per liter of solution:

Concept #2: Ionic molarity or osmolarity represents the molarity of dissolved ions in a solution.

Concept #3: Whenever two molarities or two volumes are given for one compound then a dilution is usually involved. 

Molarity Calculations

Example #1: Stock hydrochloric acid solution is 21.0% by mass HCl and has a specific gravity of 1.75. What is the molarity of the solution. 

Example #2: What is the concentration of nitrate ions in a solution that contains 83.3 g lead (IV) nitrate, Pb(NO3)4, dissolved in 700 mL solution? MW of Pb(NO3)4 is 455.24 g/mol.

Example #3:

How many micrograms of K2CO3 are required to prepare 120 mL of 0.325 M K2CO3? MW of K2CO3 is 138.21 g/mol.

 

Example #4:

If 50.0 mL of water is added to 80.0 mL of a 6.00 M solution, what will be the new concentration of the new solution?

Example #5:

To what volume should you dilute 72.93 mL of a 7.505 M LiCl solution so that 23.25 mL contains 2.25 g LiCl? MW of LiCl is 42.392 g/mol. 

Example #6: 870.0 g of water contains 0.990 g of sodium phophate, Na3PO4. Determine the concentration of Na3PO4 if the density of the solution is 1.10g/mL. MW of NA3PO4 is 163.94 g/mol.

Additional Problems
Concentrated HCl is usually available at a concentration of 37.7 % by mass. What is its molar concentration? (The density of the solution is 1.19 g/mL). 
Which of the following concentration units is temperature dependent? A. mass percent B. ppm C. mole fraction D. molality E. none of the above.
Which of the following concentration units would you  NOT use when conducting an experiment in which you place a solution in a hot water bath?  a) Molality b) Mass percent  c) Parts per million d) Molarity  e) Mole fraction 
A concentrated aqueous ammonia solution has a density of 0.90 g/mL and is 28.0% by mass ammonia. Determine the molar concentration of this solution. a) 15 M b) 1.5 M c) 0.032 M d) 31 M e) 3.0 M
You may want to reference (Pages 586 - 592) Section 13.5 while completing this problem.What is the molarity of a 11.1 % by mass glucose (C6H12O6) solution? (The density of the solution is 1.03 g/mL .)
Nitric acid is usually purchased in a concentrated form that is 70.3% HNO3 by mass and has a density of 1.41 g/mL.How much concentrated solution would you take to prepare 1.15 L of 0.115 M HNO3 by mixing with water?
Hydrochloric acid is usually purchased in a concentrated form that is 37.0% HCl by mass and has a density of 1.20 g/mL.How much concentrated solution would you take to prepare 2.90 L of 0.505 M HCl by mixing with water?
The density of acetonitrile (CH3 CN) is 0.786 g/mL, and the density of methanol (CH3 OH) is 0.791 g/mL. A solution is made by dissolving 23.0 mL CH3 OH in 98.7 mL CH3 CN.What is the molality of the solution? Assuming CH3OH is the solute and CH3CN is the solvent.
The density of acetonitrile (CH3 CN) is 0.786 g/mL, and the density of methanol (CH3 OH) is 0.791 g/mL. A solution is made by dissolving 23.0 mL CH3 OH in 98.7 mL CH3 CN.Assuming that the volumes are additive, what is the molarity of CH3 OH in the solution?
Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass.What is the molarity of this solution? (Assume a density of 1.01 g/mL.)
Commercial concentrated aqueous ammonia is 28% NH3 by mass and has a density of 0.90 g/mL. You may want to reference (Pages 539 - 541)Section 13.4 while completing this problem.What is the molarity of this solution?
Brass is a substitutional alloy consisting of a solution of copper and zinc. A particular sample of red brass consisting of 81.0% Cu and 19.0% Zn by mass has a density of 8760 kg/m3 .What is the molarity of Zn in the solution?
The density of toluene (C7H8) is 0.867 g/mL, and the density of thiophene (C4H4S) is 1.065 g/mL. A solution is made by dissolving 8.60 g of thiophene in 260 mL of toluene. You may want to reference (Pages 539 - 541) Section 13.4 while completing this problem. Assuming that the volumes of the solute and solvent are additive, what is the molarity of thiophene in the solution?
The "free-base" form of cocaine (C17H21NO4) and its protonated hydrochloride form (C17H22ClNO4) are shown below; the free-base form can be converted to the hydrochloride form with one equivalent of HCl. For clarity, not all the carbon and hydrogen atoms are shown; each vertex represents a carbon atom with the appropriate number of hydrogen atoms so that each carbon makes four bonds to other atoms. The free-base form of cocaine has a solubility of 1.00 g in 6.70 mL ethanol (CH3CH2OH). Calculate the molarity of a saturated solution of the free-base form of cocaine in ethanol.
The "free-base" form of cocaine (C17H21NO4) and its protonated hydrochloride form (C17H22ClNO4) are shown below; the free-base form can be converted to the hydrochloride form with one equivalent of HCl. For clarity, not all the carbon and hydrogen atoms are shown; each vertex represents a carbon atom with the appropriate number of hydrogen atoms so that each carbon makes four bonds to other atoms. The hydrochloride form of cocaine has a solubility of 1.00 g in 0.400 mL water. Calculate the molarity of a saturated solution of the hydrochloride form of cocaine in water.
The "free-base" form of cocaine (C17H21NO4) and its protonated hydrochloride form (C17H22ClNO4) are shown below; the free-base form can be converted to the hydrochloride form with one equivalent of HCl. For clarity, not all the carbon and hydrogen atoms are shown; each vertex represents a carbon atom with the appropriate number of hydrogen atoms so that each carbon makes four bonds to other atoms. How many mL of a concentrated 18.6 MHCl aqueous solution would it take to convert 1.00 kilograms (a "kilo") of the free-base form of cocaine into its hydrochloride form?
A solution of 49.1% H2SO4 by mass has a density of 1.39 g/cm3 at 293 K. A 24.1 cm3 sample of this solution is mixed with enough water to increase the volume of the solution to 99.4 cm3 .Find the molarity of sulfuric acid in the obtained solution.
A solution is prepared by mixing 631 mL of methanol with 501 mL of water. The molarity of methanol in the resulting solution is 14.29 M. The density of methanol at this temperature is 0.792 g/mL.Calculate the difference in volume between this solution and the total volume of water and methanol that were mixed to prepare the solution.
A solution is prepared by dissolving 11.60 g of a mixture of sodium carbonate and sodium bicarbonate in 1.00 L of water. A 300.0-cm3 sample of the solution is then treated with excess HNO3 and boiled to remove all the dissolved gas. A total of 0.949 L of dry CO2 is collected at 298 K and 0.972 atm.Find the molarity of the carbonate in the solution.
A solution is prepared by dissolving 11.60 g of a mixture of sodium carbonate and sodium bicarbonate in 1.00 L of water. A 300.0-cm3 sample of the solution is then treated with excess HNO3 and boiled to remove all the dissolved gas. A total of 0.949 L of dry CO2 is collected at 298 K and 0.972 atm.Find the molarity of the bicarbonate in the solution.
During a persons typical breathing cycle, the CO2 concentration in the expired air rises to a peak of 4.6% by volume.What is the molarity of the CO2 in the expired air at its peak, assuming a body temperature of 37 oC?
Glucose makes up about 0.10% by mass of human blood.What further information would you need to determine the molarity of the solution?
The density of a 21.0% by mass ethylene glycol (C2 H6 O2 ) solution in water is 1.04 g/mL .Find the molarity of the solution.
What is the molarity of the solution 0.0433 m LiF, if the density is 1.10g/mL?
A solution of H2SO4(aq) with a molal concentration of 4.37 m has a density of 1.233 g/mL. What is the molar concentration of this solution?
What is the molarity of NO 3- in each solution? A) 0.190 M KNO3. B) 0.300 M Ca(NO3)2. C) 0.400 M Al(NO3)3.
A solution of H2SO4(aq) with a molal concentration of 3.58 m has a density of 1.200 g/mL.What is the molar concentration of this solution?
Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass. What is the molarity of this solution? (Assume a density of 1.01 g/mL.)
What is the concentration of K+ in 0.15 M of K2S ?
Choose the correct statement: A. Molarity is defined as moles of solute per liter of solvent. B. % by mass is defined as grams of solute per 100 g of solvent. C. % by volume is defined as grams of solute per 100 L of solution. D. Molarity is defined as moles of solute per liter of solution. E. All of the above.
Use the following graph to determine the molar absorptivity of Bromothymol blue (BTB)? Assume a cuvet with a 14.45 mm diameter was used.
if CaCl2  is dissolved in water, what can be said about the concentration of the Ca 2+ ion?
What is the molarity of a 1.484  m solution of sucrose, C12H22O11? The density of the solution is 1.127 g/mL.A. 1.672 MB. 1.484 MC. 3.400 MD. 1.109 ME. 0.958 M
An aqueous solution of tartaric acid, H2C4H4O6, is 0.278 m and has a density of 1.006 g/mL. What is the molarity of the solution? (molar mass = 150.09 g/mole)
From the Beer-Lambert Law,  A=ebc Where A is absorbance, e is the molar absorbtivity, b is the path length of the sample - that is, the path length of the cuvette in which the sample is contained, and c is the concentration of the compound in solution. If someone measured a certain absorbance from a solution with a known concentration from the spectrometer, and then measured another solution of the same species at the same wavelength in the same spectrometer, is it possible to calculate the concentration of the second substance (which is currently an unknown)?
A florist prepares a solution of nitrogen-phosphorus fertilizer by dissolving 5.66 g of NH4NO3 and 4.42 g of (NH4)3PO4 in enough water to make 20.0 L of solution. What are the molarities of NH4 + and of PO4 3– in the solution?
The total concentration of dissolved particles in blood is 0.30 M. An intravenous (IV) solution must be isotonic with blood, which means it must have the same concentration. (a) To relieve dehydration, a patient is given 100. mL/h of IV glucose (C6H12O6) for 2.5 h. What mass (g) of glucose did she receive?
The total concentration of dissolved particles in blood is 0.30 M. An intravenous (IV) solution must be isotonic with blood, which means it must have the same concentration.(b) If isotonic saline (NaCl) is used, what is the molarity of the solution?
The total concentration of dissolved particles in blood is 0.30 M. An intravenous (IV) solution must be isotonic with blood, which means it must have the same concentration.(c) If the patient is given 150. mL/h of IV saline for 1.5 h, how many grams of NaCl did she receive?
The US Environmental Protection Agency (EPA) places limits on the quantities of toxic substances that may be discharged into the sewer system. Limits have been established for a variety of substances, including hexavalent chromium, which is limited to 0.50 mg/L. If an industry is discharging hexavalent chromium as potassium dichromate (K2Cr2O7), what is the maximum permissible molarity of that substance?
Calculate the molarity of each aqueous solution: (a) 25.5 mL of 6.25 M HCl diluted to 0.500 L with water
Calculate the molarity of each aqueous solution:(b) 8.25 mL of 2.00×10–2 M KI diluted to 12.0 mL with water
The hardness of water (hardness count) is usually expressed in parts per million (by mass) of CaCO3, which is equivalent to milligrams of CaCO3 per liter of water. What is the molar concentration of Ca2+ ions in a water sample with a hardness count of 175 mg CaCO3/L?
How would you prepare the following aqueous solutions?(a) 365 mL of 8.55×10–2 M KH2PO4 from solid KH2PO4 
The level of mercury in a stream was suspected to be above the minimum considered safe (1 part per billion by weight). An analysis indicated that the concentration was 0.68 parts per billion. Assume a density of 1.0 g/mL and calculate the molarity of mercury in the stream.
How would you prepare the following aqueous solutions?(b) 465 mL of 0.335 M NaOH from 1.25 M NaOH
How would you prepare the following aqueous solutions?(a) 2.5 L of 0.65 M NaCl from solid NaCl
How would you prepare the following aqueous solutions?(b) 15.5 L of 0.3 M urea [(NH2)2C=O] from 2.1 M urea
In Canada and the United Kingdom, devices that measure blood glucose levels provide a reading in millimoles per liter. If a measurement of 5.3 mM is observed, what is the concentration of glucose (C6H12O6) in mg/dL?
How would you prepare the following aqueous solutions? (a) 1.40 L of 0.288 M KBr from solid KBr
How would you prepare the following aqueous solutions?(b) 255 mL of 0.0856 M LiNO3 from 0.264 M LiNO3
A throat spray is 1.40% by mass phenol, C6H5OH, in water. If the solution has a density of 0.9956 g/mL, calculate the molarity of the solution.
How would you prepare the following aqueous solutions?(a) 57.5 mL of 1.53×10–3 M Cr(NO3)3 from solid Cr(NO3)3
How would you prepare the following aqueous solutions?(b) 5.8×103 m3 of 1.45 M NH4NO3 from 2.50 M NH4NO3
A cough syrup contains 5.0% ethyl alcohol, C2H5OH, by mass. If the density of the solution is 0.9928 g/mL, determine the molarity of the alcohol in the cough syrup.
D5W is a solution used as an intravenous fluid. It is a 5.0% by mass solution of dextrose (C6H12O6) in water. If the density of D5W is 1.029 g/mL, calculate the molarity of dextrose in the solution.
Find the molarity of a 40.0% by mass aqueous solution of sulfuric acid, H2SO4, for which the density is 1.3057 g/mL.
Solutions of hydrogen in palladium may be formed by exposing Pd metal to H2 gas. The concentration of hydrogen in the palladium depends on the pressure of H2 gas applied, but in a more complex fashion than can be described by Henry’s law. Under certain conditions, 0.94 g of hydrogen gas is dissolved in 215 g of palladium metal (solution density = 10.8 g cm3).(a) Determine the molarity of this solution.
The three aqueous ionic solutions represented below have total volumes of 25. mL for A, 50. mL for B, and 100. mL for C. If each sphere represents 0.010 mol of ions, calculate:(a) the total molarity of ions for each solution;
The three aqueous ionic solutions represented below have total volumes of 25. mL for A, 50. mL for B, and 100. mL for C. If each sphere represents 0.010 mol of ions, calculate:(b) the highest molarity of solute;
Thermal pollution from industrial wastewater causes the temperature of river or lake water to rise, which can affect fish survival as the concentration of dissolved O2 decreases. Use the following data to find the molarity of O2 at each temperature (assume the solution density is the same as water).
Air in a smoky bar contains 4.0×10−6 mol/L of CO. What mass of CO is inhaled by a bartender who respires at a rate of 11 L/min during an 8.0-h shift?
You may want to reference (Pages 586 - 588) Section 13.5 while completing this problem.A sodium nitrate solution is 12.5 % NaNO3 by mass and has a density of 1.02 g/mL. Calculate the molarity of the solution.
A water treatment plant needs to attain a fluoride concentration of 4.50×10−5 M in the drinking water it produces. (a) What mass of NaF must be added to 5000. L of water in a blending tank?
A water treatment plant needs to attain a fluoride concentration of 4.50×10−5 M in the drinking water it produces.(b) What mass per day of fluoride is ingested by a person who drinks 2.0 L of this water?
An automobile antifreeze mixture is made by mixing equal volumes of ethylene glycol (d = 1.114 g/mL; ℳ = 62.07 g/mol) and water (d = 1.00 g/mL) at 20°C. The density of the mixture is 1.070 g/mL. Express the concentration of ethylene glycol as:(c) Molarity
You may want to reference (Pages 586 - 592)section 13.5 while completing this problem.One brand of laundry bleach is an aqueous solution containing 4.00% sodium hypochlorite (NaOCl) by mass. What is the molarity of this solution? (Assume a density of 1.02 g/mL)
What is the concentration (M) of lithium ions in 4.57 L of a 2.35 M Li3P solution?a. 45.0 Mb. 14.1 Mc. 2.35 Md. 7.05 Me. 99.0 M