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Exam%202A%20F06%20&%20Key - CHEM 4:011 PRINCIPLES OF...

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CHEM 4:011 – PRINCIPLES OF CHEMISTRY I EXAM #2 (30 QUESTIONS, 1½ HOURS) 12-October-2006 FORM A 1 J = 9.870 × 10 3 L·atm c of H 2 O( ) = 4.184 J/(g·K) R = 0.08206 (L·atm)/(mol·K) = 8.314 J/(mol·K) 1. The compression of a sample of gas in a cylinder fitted with a piston required 500. J of work. Simultaneously this gas lost 0.200 kJ of heat to its surroundings. Calculate the change in internal energy ( Δ E) of this gas. (A) 300. J (B) +300. J (C) 700. J (D) +700. J (E) 200. J 2. Magnesium metal (0.100 mol) and a volume of aqueous hydrochloric acid that contains 0.500 mol of HCl are combined and react to completion. How many liters of hydrogen gas, measured at STP, are produced? Mg(s) + 2HCl(aq) MgCl 2 (aq) + H 2 (g) (A) 2.24 L of H 2 (B) 4.48 L of H 2 (C) 5.60 L of H 2 (D) 11.2 L of H 2 (E) 22.4 L of H 2 3. Four identical flasks contain four different gases at standard pressure and temperature. Flask A contains CH 4 , flask B contains CO 2 , flask C contains N 2 , and flask D contains O 2 . Assuming ideal gas behavior which flask contains the largest number of molecules? (A) flask A (B) flask B (C) flask C (D) flask D (E) All four flasks contain the same number of molecules.
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2 4. A 1.00 liter He gas cylinder at 25ºC and 15.0 atm is used to fill party balloons. If each balloon is filled to 100. mL in size with 1.07 atm of He at 25ºC, how many balloons can be completely filled by this gas cylinder? (A) 1.40 × 10 2 (B) 1.50 × 10 2 (C) 138 (D) 162 (E) 14 5. What is the enthalpy change for the general reaction 3 B C based on the following: A 2 B Δ H rxn = Δ H 1 3 A 2 C Δ H rxn = Δ H 2 (A) Δ H 2 3 Δ H 1 (B) 3 Δ H 1 Δ H 2 (C) (1/3) Δ H 2 Δ H 1 (D) (1/2) [ Δ H 2 3 Δ H 1 ] (E) 3 Δ H 1 + (1/2) Δ H 2 6. What is the partial pressure of O 2 in millimeters of mercury in a gaseous mixture containing 3.00 g of O 2 , 3.00 g of N 2 , and 3.00 g of Ar and having a total pressure of 6.00 × 10 2 millimeters of mercury? (A) 56.2 mmHg (B) 2.36 × 10 2 mmHg (C) 2.00 × 10 2 mmHg (D) 2.04 × 10 2 mmHg (E) 112 mmHg 7. In the diagram, each container (A, B, & C) has the same volume. If containers A and C each initially contain a gas at a pressure of 1.0 atm and B is empty, what will be the final pressure in container B if the stopcock valves between the containers are opened under conditions of constant temperature? (A) 0.33 atm (B) 0.50 atm (C) 0.67 atm (D) 0.75 atm (E) 2.0 atm
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3 8. For an ideal gas, which two variables are inversely proportional to each other, if all other conditions are held constant? (A) P,
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This note was uploaded on 03/27/2008 for the course CHEM 4:12 taught by Professor Larsen during the Spring '08 term at University of Iowa.

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Exam%202A%20F06%20&%20Key - CHEM 4:011 PRINCIPLES OF...

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