View Attempt 1 of 5

Title: Started: Submitted: Time spent: C56HW October 7, 2011 6:26 PM October 7, 2011 7:02 PM 00:36:31 Total score adjusted by 0.0 Maximum possible

Total score: 7/12 = 58.3333% score: 12

1.
Consider two 1-L samples of gas, one H2 and one O2, both at 1 atm and 25C. Which statement most accuratey compares the gases? Student Response A. The rate of effusion of the O2 is greater than that of the H2. B. The rate of effusion of the O2 is equal to that of the H2. The average molecular speed of the O2 is greater C. than that of the H2. D. The average molecular speed of the O2 is equal to that of the H2. E. None of these Score: 0/1 Correct Answer

2.
Select the gas with the highest average kinetic energy per mole at 298 K. Student Response A. O2 B. CO2 C. H2O D. H2 All have the same average kinetic energy. E. Score: 1/1 Correct Answer

3.
In an effusion experiment it required 40 s for a certain number of moles of a gas of unknown molar mass to pass through a small orifice into a vacuum. Under the same conditions 16 s were required for the same number of moles of O2 to effuse. What is the molar mass of the unknown gas? Student Response A. 5.1 g/mol B. 12.8 g/mol C. 80 g/mol D. 100 g/mol 200 g/mol E. Score: 1/1 Correct Answer

4.
A 3.0-L sample of helium was placed in a container fitted with a porous membrane. Half of the helium effused through the membrane in 24 hours. A 3.0-L sample of oxygen was placed in an identical container. How many hours will it take for half of the oxygen to effuse through the membrane? Student Response A. 8.5 h B. 12 h C. 48 h D. 60. h 68 h E. Score: 1/1 Correct Answer

5.
An unknown gas Q effuses 1.74 times as fast under the same conditions as Xe gas. What is the molar mass (g/mol) of Q? Do not type the units with your answer. Student Response Correct Answer

Answer: not answered Score: 0/1

43.4

6.
Molecular size in real gases causes positive deviations from the PV/RT ratio of an ideal gas. Student Response True A. B. False Score: 1/1 Correct Answer

7.
Combustion of one mole of methane releases 802.3 kilojoules of energy. How much energy does that represent in kilocalories? Student Response A. 1.92 101 kcal 1.92 102 kcal B. C. 3.36 103 kcal D. 1.92 105 kcal E. 3.36 106 kcal Score: 1/1 Correct Answer

8.
What is the change in internal energy (in J) of a system that releases 322 J of thermal energy to its surroundings and has 142 cal of work done on it? Student Response Answer: not answered 272 Score: 0/1 Correct Answer

9.

Calculate q in J when 8.32 g of ice is cooled from -15.3C to -92.5C (cice = 2.087 J/gK). Do not add units to your answer. Student Response Correct Answer Answer: 1340.49 -1,340 Score: 0/1

10.
For the process described, compare ( H with ( E of the system. A solid yields a mixture of gases in an exothermic reaction that takes place in a container of variable volume. Student Response (H is less than (more negative) ( E of the system. A. B. (H is greater than (E of the system. C. ( H is equal to (E of the system. D. can't be determined without more information Score: 0/1 Correct Answer

11.
A 28.5 g sample of iron is heated to 95.0 C and then dropped into 58.0 g of water in a coffee-cup calorimeter. The temperature of the water rises from 23.5 C to 27.1 C. Calculate the specific heat of iron. The specific heat capacity of water is 4.184 J/g.C. Student Response A. 0.11 J B. 0.45 J C. 2.2 J D. 1.6 x Correct Answer

E. 7.8 x Score: 1/1 J

12.
If the heat capacity of a ceramic cup is 0.820 J is required to raise the temperature of the cup from 25.0 50.0 C? Student Response A. 82.0 J 20.5 J B. C. 41.0 J D. 50.0 J E. 61.0 J Score: 1/1 Correct Answer , how much heat C to