Exam-1-A - Fall 2010 CHEMISTRY 104 Section 001 Exam 1 Name:...

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Fall 2010 CHEMISTRY 104 Section 001 Exam 1 Name: ____________________ ID: XXX-XX-_ ______ Seat #: ___ 1. Which of the following chemical or physical changes is an endothermic process? A) the combustion of gasoline B) the mixing of sulfuric acid and water C) the evaporation of water D) the freezing of water E) none of these 2. The reaction is known to be zero order in A with a rate constant of 5.0 10 -2 mol/L s at 25 o C. An experiment was run at 25 o C where [A] o = 2.6e–3 M. The half-life for the reaction is A) 5.0e-2 s B) 2.6e–2 s C) 2.6e2 s D) 5.2e–2 s E) none of these 3. A 3.140 molal solution of NaCl is prepared. How many grams of NaCl are present in a sample containing 2.678 kg of water? A) 491.4 g B) 298.1 g C) 143.9 g D) 840.9 g E) none of these 4. Calculate the osmotic pressure (in torr) of 6.00 L of an aqueous 0.245 M solution at 30. o C, if the solute concerned is totally ionized into three ions (e.g., it could be Na 2 SO 4 or MgCl 2 ). A) 1.38e3 torr B) 1.39e4 torr C) 4.63e3 torr D) 1.54e3 torr E) 18.3 torr Page 1
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2 is at 5.2 atm and –57°C. Under atmospheric conditions present in a typical Boulder, Colorado, laboratory ( P = 630 torr, T = 23°C), solid CO 2 will: A) remain solid. B) boil. C) sublime. D) melt. E) none of these 6. The reaction A B + C is second order in A. When [A] 0 = 0.100 M, the reaction is 20.0% complete in 42.1 minutes. Calculate the value of the rate constant (in L/min mol). A) 9.50e–1 B) 4.75e–4 C) 1.34e0 D) 5.94e–2 E) none of these 7. A cucumber is placed in a concentrated salt solution. What will most likely happen? A) Water will flow from the solution to the cucumber. B) Salt will precipitate out. C) No change will occur. D) Water will flow from the cucumber to the solution. E) Salt will flow into the cucumber. 8. A sample of wood from an Egyptian mummy case gives a count of 7.6 cpm/gC (counts per minute per gram of carbon). How old is the wood? (The initial decay rate of is 15.3 cpm/gC, and its half-life is 5730 years.) Ignore significant figures for this problem. A) 5785 yr
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Exam-1-A - Fall 2010 CHEMISTRY 104 Section 001 Exam 1 Name:...

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