Suggest Prob 1_Solutions

Suggest Prob 1_Solutions - kapur (rk7259) – Suggested...

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Unformatted text preview: kapur (rk7259) – Suggested Problems 1 – rowland – (53210) 1 This print-out should have 40 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Some water is added to an empty glass. A sugar cube is then dropped in and dissolved. The water is the ? and the sugar is the ? . 1. solute; solution 2. solution; solute 3. acid; base 4. solvent; solute correct 5. solvent; solution Explanation: The sugar is dissolved in the water; the water is the solvent and the sugar is the solute. (Generally, the substance present in smaller proportions is the solute and the one present in greater proportions is the solvent.) The total mixture is a solution. 002 10.0 points A 35% by mass H 2 SO 4 (aq) solution has a density of 1 . 07 g / cm 3 . How much solution contains 12 . 37 g of H 2 SO 4 ? 1. 4 . 63257 mL 2. 11 . 5607 mL 3. . 934579 mL 4. 33 . 0307 mL correct 5. 2 . 67023 mL Explanation: 35% by mass means . 35 g H 2 SO 4 g soln , so V = 12 . 37 g H 2 SO 4 1 . 07 g / cm 3 × 1 g . 35 g H 2 SO 4 = 33 . 0307 mL . 003 10.0 points 0.0029% is equivalent to 1. 2.9 ppm. 2. 290 ppm. 3. 29 ppm. correct 4. 2900 ppm. 5. 0.29 ppm. Explanation: We need parts per million: . 0029% = . 0029 100 · 10000 10000 = 29 1 , 000 , 000 004 10.0 points A 93 gram solution of silver nitrate contains 7 grams of AgNO 3 . What is the percent by mass of silver nitrate in this solution? Correct answer: 7 . 52688%. Explanation: 005 10.0 points An unknown liquid has a vapor pressure of 88 mmHg at 45 ◦ C and 39 mmHg at 25 ◦ C. What is its heat of vaporization? 1. 32000 kJ / mol 2. 2000 kJ / mol 3. 2000 J / mol 4. 32 kJ / mol correct Explanation: Use the Clausius-Clapeyron Equation. Here, the only thing we don’t know is Δ H vap . ln( P 2 P 1 ) = Δ H vap R ( 1 T 1- 1 T 2 ) kapur (rk7259) – Suggested Problems 1 – rowland – (53210) 2 Δ H vap = R ln( P 2 /P 1 ) 1 /T 1- 1 /T 2 Δ H vap = 32 . 0 kJ / mol 006 10.0 points An unknown liquid has a vapor pressure of 88 mmHg at 45 ◦ C and a heat of vaporization of 32 kJ / mol, what is its vapor pressure at 55 ◦ C? 1. 89 . 4 mmHg 2. 61 mmHg 3. 127 mmHg correct 4. 156 mmHg Explanation: Use the Clausius-Clapeyron Equation. Here, the only thing we don’t know is P 2 . ln parenleftbigg P 2 P 1 parenrightbigg = Δ H vap R parenleftbigg 1 T 1- 1 T 2 parenrightbigg ln parenleftbigg P 2 88 parenrightbigg = 32 , 000 8 . 31 parenleftbigg 1 318- 1 328 parenrightbigg ln P 2 = 32 , 000 8 . 31 parenleftbigg 1 318- 1 328 parenrightbigg + ln 88 P 2 = e 4 . 84 = 127 mmHg 007 10.0 points Butane is a common fuel used in cigarette lighters, camping stoves and cr` eme brulee torches. Normally supplied in metal con- tainers under pressure, the fuel exists as a mixture of liquid and gas, so high tempera- tures may cause the container to explode. At 25 o C, the vapor pressure of butane is 2.3 atm....
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This note was uploaded on 01/30/2010 for the course GOV 312L taught by Professor Madrid during the Fall '07 term at University of Texas.

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Suggest Prob 1_Solutions - kapur (rk7259) – Suggested...

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