Chem 1331 Midterm 2

1. What is the pressure, in atm, of a tank of gas with a regulator that reads 1250mmHg? assimilator reaction set up exercise A. 1. 64 B. 490 C. 1. 79 D. 0. 608 E. 1. 25 polish off 0/1 2. A 147. 9-L sample of dry air is cooled from 88. 0C to 22. 1C while the pressure is maintained at 2. 85 atm. What is the final volume in L? (Do not type the units. ) Student Response Correct root Answer not answered 120. 9 stain 0/1 3. 1000 L of gas is prep moleculeic number 18d in a tank at 700 mm Hg and 2000 oC. The gas is then transferred to a 40. L tank at 200o C. The pressure inside the new tank is Student Response Correct Answer A. 14 mm Hg B. 70 mm Hg C. 280 mm Hg D. 1. 75 x 10 3 mm Hg E. 3. 64 x 103 mm Hg Score 0/1 4. The density of an unknown element in the gaseous state is 1. 60 g at 300 K and 1 atm. Which of the succeeding(a) could be the element? Student Response Correct Answer A. He B. Ne C. Ar D. E. Score 0/1 5. What is the pressure exerted by a potpourri of 0. 250 moles of and 0. 400 moles of He at 27. 0C in a 3. 00 L container? Student Response Correct Answer A. 16. 0 atm B. 5. 33 atm C. 3. 28 atm D. 2. 05 atm E. 1. 23 atm Score 0/1 6. At 25C, an unknown gas, Q, diffuses at a RATE 1. 65 time faster than that of propane, C3H8. Which of these gases is most likely to be Q? Student Response Correct Answer A. O2 B. He C. Ne D. H2O E. CH4 Score 0/1 7. In the reaction below, what volume of PCl5 (g) will be produced by the reaction of 69. 7 L of chlorine gas with excess phosphorus (P4 if all gas volumes are measured at STP?P4 (g) Cl2 = PCl5 (unbalanced) Do not take down units with your answer. Student Response Correct Answer Answer not answered 27. 9 Score 0/1 8. Consider three 5-L flasks, fitted with pressure gauges and small valves, each contain a gas at 273 K. flask A contains 4. 0 g of H2, flask B contains 4 . 0 g of He, and flask C contains 8. 0 g of CH4. Compare the flasks contents in terms of the characteristics listed. total kinetic free energy of the molecules. Student Response Correct Answer A. Flask A Flask B Flask C B. Flask A Flask B Flask C C. Flask A = Flask B = Flask C D. Flask A Flask C Flask B E. Flask C Flask B Flask A Score 0/1 9. What is the tack in internal energy (in J) of a system that absorbs 4. 07 kJ of warming from its surroundings and has 0. 66 kcal of work done on it? 1 kcal = 4. 184 kJ Express your answer in scientific format with three significant figures 1. 25 x 103 = 1. 25E3 Do not type units. Student Response Correct Answer Answer not answered 6. 83E3 (6. 83 ? 103) Score 0/1 10. If addition of 25. 132 kJ of heat to a 0. 308 kg sample of an alcohol raises its temperature from 20. 0C to 46. 15C, what is the specific heat capacity of the alcohol in J/g. K? Do not enter units with your answer. Student Response Cor rect Answer Answer not answered 3. 12 Score 0/1 11. Given the following equations Determine the enthalpy change (H) for the following reaction Student Response Correct Answer A. 844. 3 kJ/mol B. 483. 3 kJ/mol C. -241. 7 kJ/mol D. -483. 3 kJ/mol E. -844. 3 kJ/mol Score 0/1 12. High-purity benzoic acid (C6H5COOH ? Hcomb = 3227 kJ/mol) is a combustion standard for calibrating bomb calorimeters.A 1. 113 g sample burns in a calorimeter (heat capacity of calorimeter alone = 1365 J/C) that contains exactly 1. 200 kg of water. What temperature change will be observed? Student Response Correct Answer Answer not answered 4. 60 Score 0/1 13. Using information from the text Appendix, calculate ? H for the reaction. 2C2H6(g) + 7O2(g) = 4CO2(g) + 6H2O(g) Student Response Correct Answer A. 2855. 4 kJ B. 2855. 4 kJ C. 551 kJ D. 551 kJ E. None of these is within 5% of the correct answer Score 0/1 14. What mass of (g) must be burned to release 334 kJ of heat to the surroundings? Student Response Correct Answer A. 0. 426 g B. 6. 00 g C. 0. 375 g D. 2. 66 g E. 55. 6 g Score 0/1 15. An AM radio station broadcasts at about 1,031 on the radio dial. Units for AM frequencies are given in kilohertz (kHz). What is the wavelength of these radio transmissions in meters (m)? caseful only the number. Student Response Correct Answer Answer not answered 291 Score 0/1 16. A microwave photon has a frequency of 4,561 MHz.What is its energy in joules? Enter your answer in the form 1. 02E12 for 1. 02 x 1012 with three significant figures. Do not enter units with your answer. Student Response Correct Answer Answer not answered 3. 02E-24 (3. 02 ? 10-24) Score 0/1 17. What is the frequency (Hz) of a photon emitted by a hydrogen atom when its electron falls from n = 5 to 1? Enter your answer using exponential notation (1. 23 x 104 = 1. 23E4) with three significant figures and do not include units. Student Response Correct Answer Answer not answered 3. 16E15 (3. 16 ? 1015) Score 0/1 18. Which is not a possible ml value for an orbital that has the following n = 2 Student Response Correct Answer A. +2 B. 1 C. +1 Score 0/1 19. Give the number of orbitals an atom can have with the following designation 3p Student Response Correct Answer A. 6 B. 2 C. 3 D. 4 E. an infinite number Score 0/1 20. Which subatomic particle was found to be present in cathode rays? Type its name only in the box. Student Response Correct Answer 1. not answered Equals electron (100%) Equals electrons (100%) Score 0/1