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Practice Midterm 1

# Practice Midterm 1 - 1(5 pts Assume that you have a...

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1. (5 pts) Assume that you have a cylinder with a moveable piston. What temperature would be needed to decrease the volume by a factor of five times the original volume while holding the pressure constant? a) T 1 = 1/5 T 2 b) T 2 = 1/2 T 1 c) T 2 = 5 T 1 d) T 1 = 5 T 2 e) No change in temperature is needed. 2. (6 pts) At 25 0 C and 748 mm Hg, a sample of gas has a volume of 125 mL. What would be the temperature of the gas ( 0 C) if the pressure was increased to 2.25 atm and the volume was reduced to 12.5 mL? a) 58.6 0 C b) -205 0 C c) 12.4 0 C d) -38.6 0 C e) none of the above 3. (5 pts) Which of the following statements are true? I) Equal volumes of gases at the same temperature and pressure contain the same numbers of molecules. II) In a given sample of an ideal gas, gas molecule behavior is dependent upon molecular attraction and repulsion. III) The volume of a fixed quantity of gas maintained at constant temperature is inversely proportional to pressure IV) Gases occupy ~0.1% of the total volume of a container. V) Standard temperature and pressure are 25.0 o C and 1.000 atm 4. (6 pts) How many grams of CaH 2 are needed to generate 25.0 L of H 2 gas if the pressure of is 760 mm Hg at 150 0 C ? (MW: CaH 2 = 42.10, H 2 = 2.00) R = 0.0821 L atm/mol K CaH 2 (s) + 2 H 2 O(l) Ca(OH) 2 (aq) + 2 H 2 (g) 1

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5. (7 pts) Calculate the density (g/L) of methane, CH 4 , at 0.00 o C and 50.0 atm. (atomic weights: C = 12.01, H = 1.008) R = 0.0821 L atm/mol K 6. (7 pts) An "empty" container is not really empty if it contains air. How may moles of nitrogen are in an "empty" two-liter bottle at atmospheric pressure (1 atm) and room temperature (25 0 C)? Air contains approximately 78% nitrogen. Assume ideal behavior. a) 6.38 x 10 -2 moles b) 4.21 x 10 -3 moles c) 0.344 moles d) 1.44 x 10 -2 moles e) 0.780 moles
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Practice Midterm 1 - 1(5 pts Assume that you have a...

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