Chem108Fall13-PT-Ch13 PDF

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Chemistry 108 Chapter 13 Multiple Choice 1.Which response lists all the following pairs that are miscible liquids. Pair #1: octane (C8H18) and water Pair #2: acetic acid (CH3COOH) and water Pair #3: octane (C8H18) and carbon tetrachloride (CCl4) A) 1, 3 B) 1, 2 C) 3 D) 2 E) 2, 3 Ans: E Category: Medium Section: 13.2 2.In which of the following solvents would you expect KBr to be most soluble? A) C6H14 (hexane) D) CCl4 (carbon tetrachloride) B) CH3CH2OH (ethanol) E) C6H12 (cyclohexane) C) C6H6 (benzene) Ans: B Category: Medium Section: 13.2 3.A 9.50 % by mass solution of acetone (C3H6O) in water has a density of 0.9849 g/mL at 20°C. What is the molarity of this solution? A) 0.621 M B) 1.61 M C) 1.66 M D) 1.71 M E) 16.9 M Ans: B Category: Medium Section: 13.3 4.Which of the following gives the molarity of a 17.0 % by mass solution of sodium acetate, CH3COONa (molar mass = 82.0 g/mol) in water? The density of the solution is 1.09 g/mL. A) 2.26  10 – 6 M B) 0.207 M C) 2.07 M D) 2.26 M E) 2.72 M Ans: D Category: Medium Section: 13.3 5.Determine the mass percent HCl in a 1.2 M solution of hydrochloric acid with a density of 1.019 g/mL? A) 3.0 % B) 4.3 % C) 8.6 % D) 13% E) 30. % Ans: B Category: Medium Section: 13.3 6.In how many grams of water should 25.31 g of potassium nitrate (KNO3) be dissolved to prepare a 0.1982 m solution? A) 250.0 g B) 792.0 g C) 1,000. g D) 1,263 g E) 7,917 g Ans: D Category: Medium Section: 13.3

7.Which of the following has the greater molal concentration (molality)? A) 1.0 m KNO3 B) 1.0 M KNO3 C) Both have same molality. Ans: B Category: Medium Section: 13.3 8.According to Raoult's law, which statement is false? A) The vapor pressure of a solvent over a solution decreases as its mole fraction increases. B) The solubility of a gas increases as the temperature decreases. C) The vapor pressure of a solvent over a solution is less than that of pure solvent. D) The greater the pressure of a gas over a solution the greater its solubility. E) Ionic solutes dissociate in solution causing an enhancement of all colligative properties. Ans: A Category: Medium Section: 13.6 9.The vapor pressure of water at 20°C is 17.5 mmHg. What is the vapor pressure of water over a solution prepared from 2.00  102 g of sucrose (C12H22O11) and 3.50  102 g water? A) 0.51 mmHg D) 18.0 mmHg B) 16.0 mmHg E) 19.4 mmHg C) 17.0 mmHg Ans: C Category: Difficult Section: 13.6 10.

What is the freezing point of a solution that contains 10.0 g of glucose (C6H12O6) in 100. g of H2O? Kf for water is 1.86°C/m. A) –0.186°C B) +0.186°C C) –0.10°C D) +0.10°C E) –1.03°C Ans: E Category: Medium Section: 13.6

11.

Calculate the freezing point of a solution made from 22.0 g of octane (C8H18) dissolved in 148.0 g of benzene. Benzene freezes at 5.50°C and its Kf value is 5.12°C/m. A) –1.16°C B) 0.98°C C) 6.66°C D) 12.2°C E) 5.49°C Ans: A Category: Medium Section: 13.6

12.

What is the osmotic pressure of a solution that contains 13.7 g of propyl alcohol (C3H7OH) dissolved in enough water to make 500. mL of solution at 27°C? A) 0.014 atm B) 0.037 atm C) 0.456 atm D) 0.01 atm E) 11.2 atm Ans: E Category: Medium Section: 13.6

13.

What is the approximate Na+ ion concentration in a 0.75 M Na2CO3 solution? A) 0.375 M B) 0.75 M C) 1.25 M D) 1.50 M E) 2.25 M Ans: D Category: Easy Section: 13.6

14.

Calculate the approximate freezing point of a solution made from 21.0 g NaCl and 1.00  102 g of H2O. [Kf of water is 1.86°C/m.] A) 3.59°C B) 6.68°C C) –13.4°C D) –6.68°C E) –3.59°C Ans: C Category: Medium Section: 13.6

15.

Which of the following aqueous solutions has the lowest freezing point? A) 0.18 m KCl D) pure water B) 0.15 m Na2SO4 E) 0.20 m C2H6O2 (ethylene glycol) C) 0.12 m Ca(NO3)2 Ans: B Category: Medium Section: 13.6

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1.What is the molality of a 0.142 M Na3PO4(aq) solution that has a density of 1.015 g/mL? Ans: 0.143 m Category: Medium Section: 13.3 2.A solution is prepared by adding 6.24 g of benzene (C6H6, 78.11 g/mol) to 80.74 g of cyclohexane (C6H12, 84.16 g/mol). Calculate the mole fraction and molality of benzene in this solution. Ans: mole fraction = 0.0769; molality = 0.989 m Category: Medium Section: 13.3 3.How many liters of ethylene glycol antifreeze (C2H6O2) would you add to your car radiator containing 15.0 L of water if you needed to protect your engine to –17.8°C? (The density of ethylene glycol is 1.1 g/mL. For water, Kf = 1.86°C/m.) Ans: 8.1 L Category: Difficult Section: 13.6 4.In the course of research, a chemist isolates a new compound with an empirical formula C3H3O2. Dissolving 2.51 g of the compound in 100. g of water produces a solution with a freezing point of –0.325°C. What is the molecular formula of the compound? (For water, Kf = 1.86°C/m.) Ans: C6H6O4 Category: Difficult Section: 13.6...