Deck 10: Solutions

Question 1

Silver chloride is a relatively insoluble salt.Only 1.92 mg of AgCl will dissolve per liter of water at 25°C.What concentration of Ag⁺,in molarity units,can be present in water at 25°C?

A) 3.35 × 10−⁶ M
B) 6.70 × 10−⁶ M
C) 1.34 × 10−⁵ M
D) 9.60 × 10−⁴ M
E) 1.92 × 10−³ M

Answer 1

1.34 × 10−⁵ M

Question 2

What is the definition of molarity?

A) Mass of solute per liter of solvent
B) Mass of solute per kg of solvent
C) Moles of solute per kg of solvent
D) Moles of solute in one liter of solvent
E) Moles of solute per liter of solution

Answer 2

Moles of solute per liter of solution

Question 3

A 15 meter by 12 meter pool of water has a depth of 2.2 meters.What mass of silver ion is present in the reservoir if the concentration of silver ion is 0.14 ppm? (1 m³ = 1000 L;assume the density of the solution is 1.00 g/mL)

A) 5.5 × 10^-4 g
B) 5.5 × 10^-2 g
C) 0.55 g
D) 5.5 g
E) 55 g

Answer 3

55 g

Question 4

Concentrated nitric acid is 70.4% HNO₃ by mass.What is the mole fraction of nitric acid?

A) 0.0112
B) 0.0620
C) 0.171
D) 0.377
E) 0.405

Question 5

Concentrated sodium hydroxide is 19.4 M and has a density of 1.54 g/mL.What is the molality of concentrated NaOH?

A) 12.6 m
B) 19.8 m
C) 25.4 m
D) 29.9 m
E) 50.4 m

Question 6

What concentration of silver nitrate (in ppm)is present in 7.1 × 10^-7 M AgNO₃(aq)? For very dilute aqueous solutions,you can assume the solution's density is 1.0 g/mL.The molar mass of AgNO₃ is 169.9 g/mol.

A) 0.0071 ppm
B) 0.12 ppm
C) 0.71 ppm
D) 1.7 ppm
E) 8.3 ppm

Question 7

To prepare a solution that is 15.0% aqueous KCl by mass,one should

A) dissolve 15.0 g KCl in 85.0 g H₂O.
B) dissolve 15.0 g KCl in 1.00 × 10² g H₂O.
C) dissolve 15.0 g KCl in 0.850 mol H₂O.
D) dissolve 0.150 mol KCl in 0.850 mol H₂O.
E) dissolve 0.150 mol KCl in 1.00 mol H₂O.

Question 8

What volume of 6.0 M HNO₃ is required to prepare 250 mL of 0.40 M HNO₃?

A) 9.7 mL
B) 17 mL
C) 27 mL
D) 38 mL
E) 270 L

Question 9

If sea water contains 15 ppm gold,how many kilograms of sea water must be processed to remove 1.00 g of gold?

A) 67 kg
B) 97 kg
C) 150 kg
D) 6.7 × 10³ kg
E) 15 × 10⁴ kg

Question 10

Concentrated phosphoric acid is 85.0% by mass H₃PO₄.If the molarity of concentrated H₃PO₄ is 14.5 M,what is the density?

A) 0.60 g/mL
B) 1.67 g/mL
C) 1.87 g/mL
D) 1.95 g/mL
E) 2.07 g/mL

Question 11

What mass of HCl is required to prepare 1.00 kg of 5.5% by mass aqueous HCl?

A) 0.018 g
B) 5.5 g
C) 18 g
D) 55 g
E) 550 g

Question 12

What is the mole fraction of water in a solution that is 33.3% by mass ethylene glycol? The molar mass of ethylene glycol,HOCH₂CH₂OH,is 62.07 g/mol.

A) 0.127
B) 0.290
C) 0.368
D) 0.667
E) 0.873

Question 13

Concentrated sulfuric acid is 18.0 M and has a density of 1.84 g/mL.Calculate the percent mass of sulfuric acid in concentrated H₂SO₄.

A) 17.7%
B) 32.5%
C) 78.2%
D) 96.0%
E) 99.4%

Question 14

Pure acetic acid,CH₃CO₂H(l),has a density of 1.049 g/mL.To prepare 1.00 L of 6.00 M CH₃CO₂H(aq),one may dilute:

A) 175 g of acetic acid to a volume of 1.00 L.
B) 343 mL of acetic acid to a volume of 1.00 L.
C) 360 mL of acetic acid to a volume of 1.00 L.
D) 382 mL of acetic acid to a volume of 1.00 L.
E) 1049 g of acetic acid to a volume of 1.00 L.

Question 15

Silver chloride is a relatively insoluble salt.Only 1.92 mg of AgCl will dissolve per liter of water at 25°C.How many parts per million of Ag⁺ can be present in water at 25°C? Assume the density of the solution equals the density of water,1.00 g/mL.

A) 0.52 ppm
B) 0.93 ppm
C) 1.45 ppm
D) 9.30 ppm
E) 52.0 ppm

Question 16

What mass of Cu(NO₃)₂ (187.6 g/mol)is present in 25.0 g of 1.00 m Cu(NO₃)₂(aq)?

A) 3.95 g
B) 4.69 g
C) 13.8 g
D) 25.0 g
E) 63.5 g

Question 17

The mole fraction of calcium chloride in an aqueous solution is 0.0724.What is the percent mass of CaCl₂ in the solution?

A) 4.46%
B) 7.24%
C) 32.5%
D) 36.2%
E) 50.0%

Question 18

A bottle of phosphoric acid is labeled "85.0% H₃PO₄ by mass;density = 1.689 g/cm³." Calculate the molarity of phosphoric acid in the solution.

A) 16.7 M
B) 14.6 M
C) 12.2 M
D) 8.67 M
E) 0.146 M

Question 19

If 26.5 g of methanol (CH₃OH)is added to 735 g of water,what is the molality of the methanol?

A) 0.0348 m
B) 2.03 m
C) 1.13 m
D) 3.61 m
E) 36.1 m

Question 20

Pure acetic acid,often called glacial acetic acid,is a liquid with a density of 1.049 g/mL.Which calculation correctly shows how to determine the volume of glacial acetic acid necessary to prepare 250 mL of 0.400 M CH₃CO₂H(aq)?

A) $\left(\frac{0.400 \mathrm{~mol}}{\mathrm{~L}}\right)\left(\frac{60.05 \mathrm{~g}}{\mathrm{~mol}}\right)\left(\frac{1 \mathrm{~mL}}{1.049 \mathrm{~g}}\right)=$$0.250 \mathrm{~L}$
B) $\left(\frac{1 \mathrm{~mol}}{0.400 \mathrm{~L}}\right)\left(\frac{60.05 \mathrm{~mol}}{\mathrm{~g}}\right)\left(\frac{1 \mathrm{~mL}}{1.049 \mathrm{~g}}\right)=$$0.250 \mathrm{~L}$
C) $\left(\frac{0.400 \mathrm{~mol}}{\mathrm{~L}}\right)\left(\frac{1 \mathrm{~g}}{60.05 \mathrm{~mol}}\right)\left(\frac{1 \mathrm{~mL}}{1.049 \mathrm{~g}}\right)=$$0.250 \mathrm{~L}$
D) $\left(\frac{0.400 \mathrm{~mol}}{\mathrm{~L}}\right)\left(\frac{1 \mathrm{~g}}{60.05 \mathrm{~mol}}\right)\left(\frac{1.049 \mathrm{~mL}}{1 \mathrm{~g}}\right)=$$0.250 \mathrm{~L}$
E) $\left(\frac{1 \mathrm{~mol}}{0.400 \mathrm{~L}}\right)\left(\frac{60.05 \mathrm{~mol}}{\mathrm{~g}}\right)\left(\frac{1 \mathrm{~mL}}{1.049 \mathrm{~g}}\right)=$$0.250 \mathrm{~L}$ .

Question 21

The Henry's law constant for O₂ in water at 25 °C is 1.26 × 10^-3 M/atm.What partial pressure of O₂ is necessary to achieve an equilibrium concentration of 1.5 × 10^-3 M O₂?

A) 1.9 × 10^-6 atm
B) 0.24 atm
C) 0.84 atm
D) 1.2 atm
E) 5.3 × 10⁵ atm

Question 22

In 1.00 atm of pure oxygen,the solubility of O₂(g)in water is 1.26 × 10−³ M at 25.0°C.The mole fraction of oxygen in air is 0.210.If the atmospheric pressure is 0.979 atm,what is the solubility of oxygen in air at 25.0°C?

A) 2.59 × 10−⁴ M
B) 2.65 × 10−³ M
C) 5.87 × 10−³ M
D) 6.00 × 10−³ M
E) 3.86 × 10³ M

Question 23

Which of the following aqueous solutions will freeze at the lowest temperature?

A) 0.10 m KCl
B) 0.20 m C₆H₁₂O₆ (glucose)
C) 0.050 m AlCl₃
D) 0.15 m SrBr₂
E) All of the above freeze at the same temperature.

Question 24

Henry's law states that gas solubility is

A) directly proportional to temperature of the solution.
B) directly proportional to the molar mass of the gas.
C) inversely proportional to the combined pressure of all gases over the solution.
D) inversely proportional to the pressure of the gas over the solution.
E) directly proportional to the pressure of the gas over the solution.

Question 25

All of the following statements are correct EXCEPT

A) the solubility of a gas in water decreases as the water temperature increases.
B) dissolving a solid in water is usually an exothermic process.
C) when an equilibrium is established between molecules in a solid and a solution,the solution is said to be saturated.
D) if a precipitate forms when a solution is cooled,the solution is supersaturated.
E) solubility decreases with increasing molar mass.

Question 26

A gas mixture has mole fractions of 0.24 oxygen and 0.76 nitrogen.If the total pressure of the gases is 1.44 atm at 325 K,what is the concentration,in molarity,of oxygen? (R = 0.0821 L⋅atm/mol⋅K)

A) 0.013 M
B) 0.017M
C) 0.041 M
D) 0.54 M
E) 0.069 M

Question 27

An aqueous solution contains 11.5 g of NaCl in 250.2 g of water.Calculate the vapor pressure of this solution at 25.0°C.The vapor pressure of pure water is 23.8 mm Hg at 25.0°C.

A) 3.38 mm Hg
B) 21.8 mm Hg
C) 23.5 mm Hg
D) 24.1 mm Hg
E) 31.3 mm Hg

Question 28

Which of the following liquids will be miscible with water in any proportions: ethanol (CH₃CH₂OH),carbon tetrachloride (CCl₄),hexane (C₆H₁₄),and/or formic acid (HCO₂H)?

A) ethanol and carbon tetrachloride
B) carbon tetrachloride and hexane
C) ethanol and formic acid
D) ethanol,carbon tetrachloride,and benzene
E) carbon tetrachloride,and formic acid

Question 29

The molal boiling point constant for water is 0.52°C/m.At what temperature will a mixture of 45.0 g of NaCl and 0.500 kg of water boil?

A) 98.4°C
B) 99.2°C
C) 100.0°C
D) 100.8°C
E) 101.6°C

Question 30

At 1.00 atm,1.64 × 10−³ g H₂(g)will dissolve in 1.0 L of water.What pressure of gas is necessary to obtain a concentration of 1.0 × 10−³ M H₂(g)?

A) 6.1 × 10−⁴ atm
B) 4.4 × 10−² atm
C) 1.2 atm
D) 2.2 × 10³ atm
E) 1.6 × 10³ atm

Question 31

All of the following are colligative properties EXCEPT

A) gas solubility as a function of partial pressure above a solution (Henry's law).
B) osmotic pressure.
C) vapor pressure lowering.
D) boiling point elevation.
E) freezing point depression.

Question 32

Arrange the molecules below in order of increasing solubility in water.

A) methane < methanol < chloromethane
B) methane < chloromethane < methanol
C) chloromethane < methanol < methane
D) chloromethane < methane < methanol
E) methanol < methane < chloromethane

Question 33

What is the equilibrium partial pressure of water vapor above a mixture of 44.0 g H₂O and 56.0 g HOCH₂CH₂OH at 35°C.The partial pressure of pure water at 35.0°C is 42.2 mm Hg.Assume ideal behavior for the solution.

A) 0.730 Hg
B) 18.7 mm Hg
C) 23.6 mm Hg
D) 30.8 mm Hg
E) 58.8 mm Hg

Question 34

The Henry's law constant for the solubility of nitrogen in water is 6.4 × 10−⁴ M/atm at 25°C.At 0.75 atm of N₂,what mass of N₂(g)dissolves in 1.0 L of water at 25°C?

A) 4.8 × 10−⁴ g
B) 8.5 × 10−⁴ g
C) 4.5 × 10−³ g
D) 1.3 × 10−² g
E) 2.4 × 10−² g

Question 35

What concentration unit is necessary for the calculation of boiling point elevation?

A) Molarity
B) Molality
C) Mass fraction
D) Mole fraction
E) Parts per million

Question 36

Arrange the molecules below in order of increasing solubility in water.

A) dimethyl ether < methane < methanol
B) dimethyl ether < methanol < methane
C) methane < methanol< dimethyl ether
D) methanol < dimethyl ether < methane
E) methane < dimethyl ether < methanol

Question 37

What mass of ethylene glycol,when mixed with 225 g H₂O,will reduce the equilibrium vapor pressure of H₂O from 1.00 atm to 0.800 atm at 100°C? The molar masses of water and ethylene glycol are 18.02 g/mol and 62.07 g/mol,respectively.Assume ideal behavior for the solution.

A) 15.6 g
B) 49.9 g
C) 194 g
D) 969 g
E) 3.10 × 10³ g

Question 38

If 77.5 g of ethylene glycol (HOCH₂CH₂OH)is added to 422.5 g of water,what is the mole fraction of ethylene glycol?

A) 0.00296
B) 0.0506
C) 0.183
D) 0.949
E) 2.96

Question 39

What concentration unit is necessary for the calculation of vapor pressure lowering?

A) Molarity
B) Molality
C) Mass fraction
D) Mole fraction
E) Density

Question 40

A substance that dissolves in water and conducts electricity when present in an aqueous solution is

A) metallic.
B) ionic.
C) molecular.
D) network covalent.
E) none of the above.

Question 41

At 25°C,what is the osmotic pressure of a homogeneous solution consisting of 18.0 g urea (CON₂H₄)diluted with water to 3.00 L? (R = 0.0821 L⋅atm/mol⋅K)

A) 0.205 atm
B) 2.44 atm
C) 7.33 atm
D) 12.3 atm
E) 14.7 atm

Question 42

An aqueous solution is composed of 7.50 g NaCl (MM = 58.44 g/mol)diluted to 0.100 L.Calculate the osmotic pressure of the solution at 298 K.(R = 0.0821 L⋅atm/mol⋅K)

A) 5.83 atm
B) 9.22 atm
C) 18.3 atm
D) 31.4 atm
E) 62.8 atm

Question 43

Equal masses of water and ethylene glycol (C₂H₆O₂)are mixed.At what temperature will the mixture freeze? The molal freezing point constant for water is −1.86°C/m.

A) −115°C
B) −93.0°C
C) −42.0°C
D) −30.0°C
E) −0.93°C

Question 44

The molal freezing point constant for water is -1.86°C/m.At what temperature will a solution containing 8.27 g CaCl₂ and 45.0 g H₂O begin to freeze? Assume that no ion-pairing occurs between Ca²⁺ and Cl^-.

A) -9.24°C
B) -4.62°C
C) -0.804°C
D) -0.749°C
E) +4.62°C

Question 45

Which of the following electrolytes is likely to have a van't Hoff factor equal to 3?

A) CaI₂
B) Na₃PO₄
C) KCl
D) answers a and b
E) answers a,b,and c

Question 46

A 0.230 m solution of an unknown electrolyte depresses the freezing point of water by 0.821°C.What is the Van't Hoff factor for this electrolyte? The freezing point depression constant for water is 1.86°C/m.

A) 0.521
B) 1.92
C) 2.00
D) 2.30
E) 4.41

Question 47

A solution is prepared by dissolving 4.21 g of a nonelectrolyte in 50.0 g of water.If the boiling point increases by 0.203°C,what is the molar mass of the solute? The boiling point elevation constant for water is 0.512°C/m.

A) 33.4 g/mol
B) 111 g/mol
C) 172 g/mol
D) 212 g/mol
E) 810 g/mol

Question 48

What is the boiling point of a solution containing 0.80 g caffeine,C₈H₁₀N₄O₂,dissolved in 13.20 g benzene? The boiling point of pure benzene is 80.1°C and the molal boiling point constant,K_b,is 2.53°C/m.

A) 79.8°C
B) 80.4°C
C) 80.9°C
D) 85.2°C
E) 88.2°C

Question 49

What is the molar mass of a nonpolar molecular compound if 3.42 grams dissolved in 41.8 grams benzene begins to freeze at 1.17°C? The freezing point of pure benzene is 5.50°C and the molal freezing point constant,K_f,is -5.12°C/m.

A) 2.89 g/mol
B) 69.2 g/mol
C) 96.7 g/mol
D) 126 g/mol
E) 358 g/mol

Question 50

Maple syrup is made from the sap of the maple tree.When the sap is tapped from the maple tree it is 2.0% by mass sucrose.Maple syrup is 66% by mass sucrose.What mass of sap would be required to make 0.5 kg of maple syrup?

A) 0.50 kg
B) 2.0 kg
C) 66 kg
D) 15 kg
E) 17 kg

Question 51

A solution is prepared by dissolving 5.00 g of an unknown molecular solid in water to make 1.00 L of solution.The osmotic pressure of the solution is 1.61 atm at 25°C.What is the molar mass of the solute? (R = 0.0821 L⋅atm/mol⋅K)

A) 6.37 g/mol
B) 58.44 g/mol
C) 76.0 g/mol
D) 102 g/mol
E) 180.2 g/mol

Question 52

A solution is prepared by dissolving 4.78 g of an unknown nonelectrolyte in enough water to make 375 mL of solution.The osmotic pressure of the solution is 1.33 atm at 27°C.What is the molar mass of the solute? (R = 0.0821 L⋅atm/mol⋅K)

A) 0.0203 g/mol
B) 21.2 g/mol
C) 49.4 g/mol
D) 96.8 g/mol
E) 236 g/mol