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Exam_2_Fall_2009 - MONTGOMERY COLLEGE Chem 101(Bontems Fall...

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Unformatted text preview: MONTGOMERY COLLEGE Chem 101 (Bontems, Fall, 2009 MWF) Exam #2 Name: ______________________________ Multiple Choice – In the blank, write the letter of the best answer. (3 pts. ea.) 1. _______ Which of the following is correct? a. n is indirectly proportional to V c. P is directly proportional to T b. P is directly proportional to V d. none of these 2. _______ The pressure of 3 L of gas in a flexible container is tripled then its Kelvin temperature is doubled. The volume is now _________. a. 1 L c. 3 L b. 2 L d. 18 L e. none of these 3. _______ The following reaction is done at constant T and P: CH4(g) + H2O(g) CO(g) + 3H2(g) . What happens to the volume as the reaction proceeds? a. It remains the same because the reaction is at constant T and P. b. The volume doubles. c. The volume halves. d. None of these. 4. _______The density of xenon gas at STP is a. 5.86 g/L c. 22.4 g/L b. 0.171 g/L d. none of these 5._______ How many moles of neon gas are in 3.00 L at STP? a. 67.2 moles c. 0.134 moles b. 0.179 moles d. not enough information 6. _______Which gas will sink in air at 25°C and 1 atm? N2 a. HF c. b. SO2 d. none of these e. all of these 7. _______Which of the following are non‐electrolytes? HCN, K3PO4, C3H8O a. HCN c. C3H8O b. K3PO4 d. more than one of these 8. Which of the following substances would strongly conduct electricity when dissolved? a. H2SO3 c. HNO3 b. AgCl d. Fe(OH)3 9. _______ Which of the following would produce five ions per formula unit when dissolved? Na2SO3 AlPO3 Ba3(PO4)2 LiNO3 d. LiNO3 a. Na2SO3 b. AlPO3 e. more than one of these c. Ba3(PO4)2 2 10. _______ How many moles of nitrate ion are in 2.00 L of 3.00 M Ba(NO3)2? a. 3.00 moles d. 36.0 moles b. 6.00 moles e. none of these c. 12.0 moles 11. _______ What is the partial pressure of hydrogen in a container that contains 0.25 mol H2 and 0.75 mole O2 and has a total pressure of 4.0 atm? a. 4.0 atm c. 2 atm b. 3.0 atm d. 1 atm e. insufficient information 12. True or False (2 pts each) ______ HF is a weak acid. ______ If a solution is diluted, the molarity will increase. ______ A 2 M solution of HBr contains the same concentration of bromide as a 2 M solution of BaBr2. ______ The following is an oxidation‐reduction reaction: 2Na + Cl2 2NaCl ______ The major component of air is oxygen. ______ NaOH is a weak base. ______ All soluble compounds are strong electrolytes. ‐1 13. Assign oxidation numbers to each atom of the following: MnO4 F2 (6 pts) Mn ______ O ________ F ________ 14. Define each of the following: (3 pts each) Diffusion Neutralization reaction 15. List the two conditions which cause real gases to deviate from the ideal gas law. (4 pts) 3 16. A 1.20 g sample of dry ice (CO2) is added to a 755 mL flask containing nitrogen gas at a temperature of 25.0°C and a pressure of 725 mmHg. The dry ice is allowed to sublime (convert from solid to gas) and the mixture is allowed to return to 25.0°C. What is the partial pressure of CO2 and what is the total pressure in the flask? (7 pts) 17. A gas sample is contained in a 39.1 L cylinder at 750 mm Hg and 20.0°C. If the pressure in unchanged, calculate the temperature needed to cause the gas to expand to 50.0L. (6 pts) 18. What volume of H2 gas (in L) at 748 mmHg and 86°C is needed to synthesize 25.8 g CH3OH? (8 pts) Molar masses: 30.0 1.02 32.0 CO(g) + 2H2(g) CH3OH(g) 4 19. Lead ions can be precipitated from solution with KCl according to the following reaction: Pb 2+ + 2KCl PbCl2(s) Molar masses: 207.2 74.6 278.1 When 28.5 g KCl are added to a solution containing 25.7 g Pb 2+, a PbCl2 precipitate forms. The precipitate is filtered and dried and found to have a mass of 29.4 g. Determine the limiting reactant, theoretical yield of PbCl2 and percent yield for the reaction. (8 pts) 18. Write full balanced equations, full ionic equations and net ionic equations for the following reactions: (8 pts) a. HF + Ba(OH)2 → b. Pb(NO3)4 + LiOH → Bonus: Describe the pickle demonstration and the SF6 demonstration (video) and the scientific principle being demonstrated. ...
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