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Unformatted text preview: CHAPTER 12 SAMPLE QUESTIONS K fp of water is 1.86 C/m; the K bp is 0.512 C/m; and R is 0.082 l atm/mol K 1. Liquid Q is a polar solvent and liquid R is a nonpolar solvent. On the basis of this information you would expect (A) both liquids to be miscible with a third liquid T . (B) liquid Q and H 2 O to be miscible. (C) liquid Q to be miscible with liquid R . (D) NaCl to be soluble in both Q and R . (E) CCl 4 to be immiscible with both Q and R . 2. Which of the following would you expect to be the most soluble in hexane [C 6 H 12 ]? (A) NaCl (B) ethanol (C) CH 2 Cl 2 (D) C 6 H 6 (E) water 3. Which substance is most soluble in water? (A) C 6 H 6 (B) CaCO 3 (C) C 2 H 5 OH (D) CO 2 4. When two pure substances are mixed to form a solution, which of the following is always true? (A) heat is released (B) heat is absorbed (C) there is an increase in entropy (D) there is a decrease in entropy 5. The solubility of potassium permanganate (KMnO 4 ) is 7.1 g per 100.0 g of water at 25 C. What is the mole fraction of potassium permanganate in such a solution? (A) 0.00803 (B) 0.00863 (C) 0.449 (D) 0.474 (E) 7.1 6. What is the mole fraction of water in 200. g of 95% (by mass) ethanol, C 2 H 5 OH? (A) 0.050 (B) 0.12 (C) 0.56 (D) 0.88 7. If 100 g of NaCl is dissolved in 1000 g of water, what is the mole fraction of NaCl? (A) 0.031 (B) 0.31 (C) 1.71 (D) 0.095 (E) 0.17 8. What mass of water is needed to dissolve 292.5 g of NaCl to produce a 0.25 m solution? (A) 20 kg (B) 5.0 kg (C) 0.80 kg (D) 0.050 kg 9. If 0.400 g of a substance R (molar mass = 80 g/mol) is dissolved in 100 g of liquid Q , what is the molality of the solution? (A) 4.00 x 10 3 m (B) 5.00 x 10 2 m (C) 5.00 x 10 3 m (D) 4.00 x 10 1 m 10. Cadmium bromide is used in photography. Calculate the molality of a solution prepared by dissolving 45.38 g of CdBr 2 in 375.0 mL of water (Hint: density of water = 1 g/mL) in 375....
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