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Unformatted text preview: perlick (app582) Homework #2 holcombe (51160) 1 This print-out should have 22 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Consider two closed containers. Container X is a 2 L container that contains 0.5 L of acetone. Container Y is a 2 L container that contains 1.8 L of acetone. Both containers and contents are at 30 C. Which of the following is true? 1. The vapor pressure in container X is greater. 2. You would need information about the shape of the containers to be able to answer this question. 3. The vapor pressures in both containers are equal. correct 4. The vapor pressure in container Y is greater. Explanation: 002 10.0 points Which of the following is a restatement of Henrys Law? 1. As the partial pressure of a gas above a liquid increases, the gass solubility in that liquid also increases. correct 2. Adding a non-volatile solute to a liquid will lower its vapor pressure. 3. Heating a solution will decrease the solu- bility of gases dissolved in it. 4. A mixture of two liquids will have a vapor pressure that isnt equal to either of the pure liquids vapor pressures. Explanation: Henrys law, formulated by William Henry is 1803 states: At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly propor- tional to the partial pressure of that gas in equilibrium with that liquid. 003 10.0 points The vapor pressures of pure carbon disulfide and carbon tetrachloride are 360 and 99.8 torr, respectively, at 296 K. What is the vapor pressure of a solution containing 50.0 g of each compound? 1. 274 torr correct 2. 33.0 torr 3. 460 torr 4. 241 torr 5. 260 torr Explanation: 004 10.0 points For gases that do not react chemically with water, the solubility of the gas in water gen- erally (decreases, increases) with an increase in the pressure of the gas and (decreases, in- creases) with increasing temperature. 1. decreases; decreases 2. increases; decreases correct 3. decreases; increases 4. increases; increases Explanation: An increase in pressure means that you have increased the concentration of gas above the solvent surface, thereby increasing the concentration of the gas in the solvent. In- creasing the temperature will decrease the solubility of the gas. 005 10.0 points The vapor pressure of pure CH 2 Cl 2 (molecu- lar weight = 85 g/mol) is 133 torr at 0 C and the vapor pressure of pure CH 2 Br 2 (molecu- perlick (app582) Homework #2 holcombe (51160) 2 lar weight 174 g/mol) is 11 torr at the same temperature. What is the total vapor pres- sure of a solution prepared from equal masses of these two substances?...
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This note was uploaded on 02/07/2012 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.
- Spring '07