CHEM151Take-home Q11 Key

Chemistry (MasteringChemistry Series)

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Unformatted text preview: Name Take‐Home Quiz #11 (DUE Wednesday December 10th, 2008) KEY Date Score 1) Explain the following gas laws. Include what variables are held constant, what variables are compared and what are their relationships, i.e. directly or inversely proportional. (3 points) a. Boyle’s Law V & P – inversely (n & T held constant) b. Charles’s Law V & T – directly (n & P held constant) c. Avogadro’s Law V & n – directly (T & P held constant) 2) What volume in liters is needed to contain 4.5g of H2(g) at 800 mmHg and 30.2°C? (1 point) PV = nRT 1 2.2 : 4.5 2.02 1 : 800 1.05 760 : 30.2° 273 303.2 · 1.05 2.2 · 0.0821 · · 303.2 · 55 1.05 3) Air with a pressure of 1.5 atm at 25.3°C is warmed to 85.6°C in a constant volume of 50.0 L. What is the final pressure? (1 point) V & n held constant: so it becomes: 25.3 85.6 1.5 273 273 298.3 358.6 1.5 298.3 358.6 1.5 298.3 . 358.6 4) What is the density of N2(g) at 97°F and 1.02 atm? (1 point) · :° ° ° 1.8° 32 1.8 32 36° 273 309 28.02 0.0821 · 1.02 · · · 309 . 5) Calculate the molar mass of a gas that has a density of 8.975 g/L at a pressure of 754 torr and a temperature of 25.7°C. (1 point) i. Identify the gas : 754 : 25.7 8.975 · 0.0821 0.992 1 0.992 760 273 298.7 · · · 298.7 i. Rn has an atomic mass of 222 g/mol 6) How many liters of H2(g) are produced when 15.6 g of Zn is reacted with an excess of HCl(aq) at 25°C and 1.01 atm? (2 points) 2HCl(aq) + 2Zn(s) H2(g) + 2ZnCl(aq) 15.6 1 65.39 1 2 0.119 Using PV=nRT, V can be found : 25 1.01 . . 273 · · 298 0.119 . · 0.0821 · · · 298 7) A sample of gas contains 15.4 moles of hydrogen, 30.8 moles of oxygen, and 107.8 moles of nitrogen. At 777 torr, what is the partial pressure of each gas? (Hint: can leave pressure in torr units, not using R) (1 point) ; 15.4 : 15.4 154 0.10 : 30.8 154 0.20 : 107.8 154 0.70 Extra Credit (5 points): What is the diffusion rate ratio of N2(g) versus Ar(g)? Which gas diffuses faster? 777 30.8 0.100 777 0.200 777 0.700 . 107.8 154 ...
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This document was uploaded on 09/27/2011.

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