Ch. 13 Practice test
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R - Ch 13 - two practice tests with answers
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AP Chemistry Ch. 13 Practice test 1) The process of solute particles being surrounded by solvent particles is known as __________. A) salutation B) agglomeration C) solvation D) agglutination E) dehydration Answer: C Sec. 13.1 2) The solubility of oxygen gas in water at 25 °C and 1.0 atm pressure of oxygen is 0.041 g/L The solubility of oxygen in water at 3.0 atm and 25 °C is __________ g/L. A) 0.041 B) 0.014 C) 0.31 D) 0.12 E) 3.0 Answer: D Sec. 13.3 3) The solubility of nitrogen gas in water at 25 °C and a nitrogen pressure of 1.0 atm is 6.9 × The solubility of nitrogen in water at a nitrogen pressure of 0.80 atm is __________ M. A) 5.5 × B) 8.6 × C) 1.2 × D) 3.7 × E) 0.80 Answer: A Sec. 13.3 4) On a clear day at sea level, with a temperature of 25 °C, the partial pressure of in air is 0.78 atm and the concentration of nitrogen in water is 5.3 × . When the partial pressure of is __________ atm, the concentration in water is 1.1 × . A) 0.63 atm B) 0.78 atm C) 1.0 atm D) 2.1 atm E) 1.6 atm Answer: E Sec. 13.3 5) A sample of potassium nitrate (49.0 g) is dissolved in 101 g of water at 100 °C with precautions taken to avoid evaporation of any water. The solution is cooled to 30.0 °C and a small amount of precipitate is observed. This solution is __________. A) hydrated B) placated C) saturated D) unsaturated E) supersaturated Answer: C Sec. 13.3 6) The solubility of MnSO4 monohydrate in water at 20 °C is 70.0 g per 100.0 mL of water. A solution at 20 °C that is 4.22 M in MnSO4 monohydrate is best described as a(n) __________ solution. The formula weight of MnSO4 monohydrate is 168.97 g/mol. A) hydrated B) solvated C) saturated D) unsaturated E) supersaturated Answer: E Sec. 13.3 7) The concentration of urea in a solution prepared by dissolving 16 g of urea in 39 g of is __________% by mass. The molar mass of urea is 60.0 g/mol. A) 29 B) 41 C) 0.29 D) 0.41 E) 0.48 Answer: A Sec. 13.4 8) The concentration of nitrate ion in a solution that contains 0.900 M aluminum nitrate is __________ M. A) 0.900 B) 0.450 C) 0.300 D) 2.70 E) 1.80 Answer: D Sec. 13.4 9) The concentration of KBr in a solution prepared by dissolving 2.21 g of KBr in 897 g of water is __________ molal. A) 2.46 B) 0.0167 C) 0.0207 D) 2.07 × E) 0.0186 Answer: C Sec. 13.4 10) The concentration (M) of HCl in a solution prepared by dissolving 5.5 g of HCl in 200 g of is __________ M. The density of the solution is 0.79 g/mL. A) 21 B) 0.93 C) 0.58 D) 6.0 × E) 1.72 Answer: C Sec. 13.4 11) The mole fraction of urea (MW = 60.0 g/mol) in a solution prepared by dissolving 16 g of urea in 39 g of is __________. A) 0.58 B) 0.37 C) 0.13 D) 0.11 E) 9.1 Answer: D Sec. 13.4 12) The concentration of urea (MW = 60.0 g/mol) in a solution prepared by dissolving 16 g of urea in 39 g of is __________ molal. A) 96 B) 6.9 C) 0.68 D) 6.3 E) 0.11 Answer: B Sec. 13.4 13) What is the molarity of sodium chloride in solution that is 13.0% by mass sodium chloride and that has a density of 1.10 g/mL? A) 143 B) 2.45 C) 2.56 D) 2.23 E) 1.43 × Answer: B Sec. 13.4 14) The vapor pressure of pure ethanol at 60 °C is 0.459 atm. Raoult's Law predicts that a solution prepared by dissolving 10.0 mmol naphthalene (nonvolatile) in 90.0 mmol ethanol will have a vapor pressure of __________ atm. A) 0.498 B) 0.413 C) 0.790 D) 0.367 E) 0.0918 Answer: B Sec. 13.5 15) The vapor pressure of pure water at 25 °C is 23.8 torr. What is the vapor pressure (torr) of water above a solution prepared by dissolving 18.0 g of glucose (a nonelectrolyte, MW = 180.0 g/mol) in 95.0 g of water? A) 24.3 B) 23.4 C) 0.451 D) 0.443 E) 23.8 Answer: B Sec. 13.5 16) The freezing point of ethanol is -114.6 °C. The molal freezing point depression constant for ethanol is 2.00 °C/m. What is the freezing point (°C) of a solution prepared by dissolving 50.0 g of glycerin a nonelectrolyte) in 200 g of ethanol? A) -115 B) -5.42 C) -132.3 D) -120.0 E) -114.6 Answer: D Sec. 13.5 17) What is the freezing point (°C) of a solution prepared by dissolving 11.3 g of (formula weight = 164 g/mol) in 115 g of water? The molal freezing point depression constant for water is 1.86 °C/m. A) -3.34 B) -1.11 C) 3.34 D) 1.11 E) 0.00 Answer: A Sec. 13.5 18) A solution containing 10.0 g of an unknown liquid and 90.0 g water has a freezing point of -3.33 °C. Given = 1.86°C/m for water, the molar mass of the unknown liquid is ________ g/mol. A) 69.0 B) 333 C) 619 D) 161 E) 62.1 Answer: E Sec. 13.5 19) Determine the fraction of ionization of HX if a solution prepared by dissolving 0.020 mol of HX in 115 g of water freezes at -0.47 °C. The molal freezing-point-depression constant of water is 1.86 °C/m. A) 0.044 B) 0.30 C) 0.45 D) 1.45 E) 0.348 Answer: C Sec. 13.5 20) The dissolution of gases in water is virtually always exothermic because __________. A) one of the two endothermic steps (separation of solute particles) in the solution-formation process is unnecessary B) the exothermic step in the solution-formation process is unnecessary C) gases react exothermically with water D) neither of the two endothermic steps in the solution-formation process is necessary E) all three steps in the solution-formation process are exothermic Answer: A Sec. 13.1
A) they are accompanied by another process that is exothermic B) they are accompanied by an increase in order C) they are accompanied by an increase in disorder D) the solvent is a gas and the solute is a solid E) the solvent is water and the solute is a gas Answer: C Sec. 13.1
A) gases can only dissolve other gases B) polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes C) solvents can only dissolve solutes of similar molar mass D) condensed phases can only dissolve other condensed phases E) polar solvents dissolve nonpolar solutes and vice versa Answer: B Sec. 13.1 23) Ammonium nitrate (NH4NO3) dissolves readily in water even though the dissolution is endothermic by 26.4 kJ/mol. The solution process is spontaneous because __________. A) the vapor pressure of the water decreases upon addition of the solute B) osmotic properties predict this behavior C) of the decrease in enthalpy upon addition of the solute D) of the increase in enthalpy upon dissolution of this strong electrolyte E) of the increase in disorder upon dissolution of this strong electrolyte Answer: E Diff: 2 Page Ref: Sec. 13.1 24) In a saturated solution of a salt in water, __________. A) the rate of crystallization > the rate of dissolution B) the rate of dissolution > the rate of crystallization C) seed crystal addition may cause massive crystallization D) the rate of crystallization = the rate of dissolution E) addition of more water causes massive crystallization Answer: D Sec. 13.2 25) Which one of the following substances would be the most soluble in ? A) B) C) D) E) NaCl Answer: D Sec. 13.3 26) Which one of the following substances is more likely to dissolve in ? A) B) HBr C) HCl D) E) NaCl Answer: A Sec. 13.3 27) Which one of the following is most soluble in water? A) B) C) D) E) Answer: A Sec. 13.3 28) Which one of the following concentration units varies with temperature? A) molarity B) mass percent C) mole fraction D) molality E) all of the above Answer: A Sec. 13.4 29) A 1.35 m aqueous solution of compound X had a boiling point of 101.4°C. Which one of the following could be compound X? The boiling point elevation constant for water is 0.52°C/m. A) B) C) D) KCl E) Answer: D Sec. 13.5 30) Colligative properties of solutions include all of the following except __________. A) depression of vapor pressure upon addition of a solute to a solvent B) elevation of the boiling point of a solution upon addition of a solute to a solvent C) depression of the freezing point of a solution upon addition of a solute to a solvent D) an increase in the osmotic pressure of a solution upon the addition of more solute E) the increase of reaction rates with increase in temperature Answer: E Sec. 13.5
13 Solutions PRACTICE TEST 1. What is the molality of 7.80% by weight glucose (C6H12O6 molar mass = 180.16 g/mol) solution? a) 0.470 m d) 0.0454 m b) 0.845 m e) 0.0844 m c) 0.0432 m 2. The mol fraction of NH4Cl in a solution is 0.0311. What is its molality? (The molar mass of water is 18.016 g/mol.) a) 1.78 m d) 0.562 m b) 1.66 m e) 0.0983 m c) 0.969 m
a) 0.0810 d) 0.0173 b) 0.0914 e) 0.0162 c) 0.0745 4. What is the mol fraction NaNO3 in a solution which is 2.15 m? a) 0.0180 d) 0.09387 b) 0.0268 e) 0.0785 c) 0.0373 5. A 1.34 M NiCl2 (molar mass = 129.6 g/mol) solution has a density of 1.12 g/cm3. What is the weight percent NiCl2 of the solution? a) 1.73% d) 25.4% b) 8.64% e) 29.8% c) 15.5%
6. A 1.25 M Cu(NO3)2 (molar mass = 187.56 g/mol) solution has a density of 1.19 g/cm3. What is the weight percent Cu(NO3)2 of the solution? a) 1.88% d) 14.3% b) 2.36% e) 19.9% c) 10.5%
a) 2.75 M d) 9.35 M b) 4.45 M e) 10.2 M c) 5.50 M
a) 0.55 g d) 62 g b) 7.3 g e) 98 g c) 41 g
a) 1.30 d) 0.30 b) 1.00 e) 0.23 c) 0.77
a) mol fraction d) weight % b) molarity e) ppm c) molality 11. A chemist knows the empirical formula of a new compound but not the molecular formula. What must be determined experimentally so that the molecular formula can be determined? a) density d) melting point b) viscosity e) molar mass c) % composition 12. A volumetric flask is necessary for the preparation of which one of the following concentration measurements? a) molality d) molarity b) X e) ppm c) mass % 13. If the pressure of a gas over a liquid increases, the amount of gas dissolved in the liquid will a) increase b) decrease c) remain the same d) have a higher vapor pressure e) depends on the polarity of the gas 14. Which of the following solutions would have the lowest vapor pressure? a) 1 m glucose (C6H12O6) b) 1 m MgCl2 d) 1 m NaBr c) 1 m NaNO3 e) pure H2O 15. What is the primary energetic factor in the lack of miscibility between CCl4(l) and water? a) the strength of intermolecular forces between CCl4 molecules b) the strength of intermolecular forces between H2O molecules c) the charge on the C atom in CCl4 d) the difference between the molecular weights of the molecules e) the electronegativity difference between carbon and chlorine 16. Which of the following would have a boiling point closes to that of 1 m NaCl? a) 1 m sucrose (C12H22O11) b) pure H2O d) 0.5 m CH3OH c) 1 m MgCl2 e) 1 m NH4NO3 17. Which of the following would have the highest freezing point? a) 1 m glucose (C6H12O6) b) 1 m MgCl2 d) 1 m (NH4)2SO4 c) 1 m NaNO3 e) pure H2O 18. You need a solution that is 0.15 m in ions. How many grams of MgCl2 (molar mass = 95.2 g/mol) must you dissolve in 400. g of water? (Assume total dissociation of the ionic salt.) a) 0.060 g d) 7.6 g b) 1.9 g e) 17 g c) 5.7 g
a) 93.2 g/mol d) 182 g/mol b) 112 g/mol e) 205 g/mol c) 128 g/mol
a) 52.0C d) 17.6C b) 48.7C e) 7.63C c) 45.4C 21. What is the molar mass of a compound if 4.28 grams is dissolved in 25.0 grams of chloroform solvent to form a solution which has a boiling point elevation of 2.30C. The boiling point constant of chloroform Kbp is +3.63C/m. a) 34.5 g/mol d) 168 g/mol b) 67.5 g/mol e) 270 g/mol c) 135 g/mol 22. Concentrated salt solutions have boiling points lower than those calculated using the equation, Tb = Kb · m.· i Which of the following is a reasonable explanation of this observation? a) Positive ions repel each other more at high concentration. b) Ions of opposite charge will tend to stay paired instead of breaking up. c) The water molecules will have a greater attraction for each other. d) Concentrated solutions really have small particles of non-dissolved salt, thus lowering the molality. e) The difference between the crystal lattice energy and the heat of hydration must be taken into consideration. Answers:
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