Chemistry 111A General Chemistry Practice Exam 2 PDF

Name Chemistry 111A General Chemistry Practice Exam 2 Useful equations: PV=nRT, u rms = 3RT , 760 torr = 1 atm, R = 0.08206 L.atm/mol.K, M...

Name Chemistry 111A General Chemistry Practice Exam 2 Useful equations: PV=nRT, u rms = 3RT , 760 torr = 1 atm, R = 0.08206 L.atm/mol.K, M  1 1 R = 8.314 J/mol.K, E=q+w, q=mCsT, E=h, =c, E = 2.18 10−18 J  2 − 2   ni nf  Section 1 - Multiple Choice (mark correct answer on Scantron- 3 points each) 1. Which of the following statements is (are) TRUE? a) Strong electrolytes produce only a few ions in aqueous solution b) Molecular compounds remain intact in aqueous solution c) Weak acids are fully ionized in aqueous solution d) Reasonably concentrated solutions of salts are good conductors of electricity e) b) and d) 2. Which of the following solutions has the highest concentration of ions? a) 0.2 M AlCl3 b) 0.2 M Fe2(SO4)3 c) 0.3 M Li2CO3 d) 0.3 M Cu(NO3)2 e) 0.4 M KClO4 3. How many of the following are oxidation-reduction reactions? NaOH (aq) + HCl (aq) → NaCl (aq) + H2O (l) Cu (s) + 2AgNO3 (aq) → 2Ag (s) + Cu(NO3)2 (aq) Mg(OH)2 (s) → MgO (s) + H2O (l) N2 (g) + 3H2 (g) → 2NH3 (g) a) 0 b) 1 c) 2 d) 3 e) 4 4. Addition of Ca(NO3)2 (aq) to which solution produces a precipitate? a) NH4C2H3O2 (aq) b) Pb(NO3)2 (aq) c) Na3PO4 (aq) d) K2S (aq) e) NaI (aq) 5. Which of the following is a weak acid? a) H2SO4 b) HNO3 c) H3PO4 d) HCl e) HBr 6. What is the oxidation number of Mn in potassium permanganate? a) -1 b) +1 c) +3 d) +5 e) +7 7. Which species is the reducing agent in the reaction below? Zn (s) + CuSO4 (aq) → Cu (s) + ZnSO4 (aq) a) Zn b) Cu2+ c) CuSO4 d) Zn2+ e) SO42- 8. If heat is transferred from the system to the surroundings then a) q is positive b) q is negative c) w is positive d) w is negative e) both b and d 9. Of the following, which one is a state function? a) H b) q c) w d) heat e) none of the above 10. If excess magnesium is added to 100. mL of 0.500 M hydrochloric acid, how many moles of the following reaction occur? Mg (s) + 2 HCl (aq) → MgCl2 (aq) + H2 (g) a) 0.05 b) 0.025 c) 0.0025 d) 50 e) 25 11. A gas is considered "ideal" if a) it is not compressible b) one mole of it occupies exactly 1 liter at standard temperature and pressure c) it can be shown to occupy zero volume at 0C. d) its behavior is described by the ideal-gas equation e) one mole of it in a one-liter container exerts a pressure of exactly 1 atm at room temperature 12. Of the following gases, which will have the greatest rate of effusion at a given temperature. a) NH3 b) CH4 c) Ar d) HBr  e) HCl 13. Cl2 and N2 react according to the following equation 3Cl2(g) + N2(g) → 2NCl3(g) If 4 L of a stoichiometric mixture of chlorine and nitrogen are converted to nitrogen trichloride under conditions of constant temperature and pressure what is the volume of NCl3(g) produced? a) 1L b) 2L c) 3L d) 4L e) none of the above 14. Which of the following statements is TRUE? a) State functions do not depend on the path taken to arrive at a given state. b) Erxn can be determined using constant volume Calorimetry. c) Energy is neither created nor destroyed. d) Hrxn can be determined using constant pressure Calorimetry. e) All of the above are true. 15. Given the equation S (s) + O2 (g) → SO2 (g), H = -296 kJ, which of the following statements is FALSE? a) The reaction is exothermic. b) When 1 mole sulfur is reacted, 296 kJ of energy is released to the surroundings. c) This is a combustion reaction d) The standard enthalpy of formation for SO2 (g) is –296 kJ e) Heat is absorbed during the reaction 16. Calculate the value of E for your car’s engine when it does 370 kJ of work to move the car and releases 840 kJ of heat to the cooling system. a) -1210 kJ b) -840 kJ c) -470 kJ d) 470 kJ e) 1210 kJ 17. Which one of the following is an exothermic process? a) ice melting b) water evaporating c) boiling soup d) condensation of water vapor e) Ammonium thiocyanate and barium hydroxide are mixed at 25°C: the temperature drops. 18. The value of H° for the reaction below is -126 kJ. What is H° when 1.00 mol of Na2O2 is formed in the reaction? 2 Na2O2 (s) + 2 H2O (l) → 4 NaOH (s) + O2 (g) a) -63 kJ b) 252 kJ c) 126 kJ d) 63 kJ e) -126 kJ  19. For which one of the following reactions is Hrxn equal to the heat of formation of the product? a) N2 (g) + 3 H2 (g) → 2 NH3 (g) b) ½ N2 (g) + O2 (g) → NO2 (g) c) 6 C (s) + 6 H (g) → C6H6 (l) d) P (g) + 2 H2 (g) + Br (g) → PH4Br (l) e) 12 C (s) + 11 H2 (g) + 11 O (g) → C12H22O11 (s) 20. Which of the following transitions in the Bohr hydrogen atom results in the emission of the shortest wavelength photon. a) n=1→n=6 b) n=6→n=1 c) n=6→n=3 d) n=3→n=6 e) n=1→n=4 21. Which one of the following is an incorrect subshell notation? a) 4f b) 2d c) 3s d) 2p e) 12s 22. All of the orbitals in a given subshell have the same value of which quantum number(s)? a) principal only b) angular momentum only c) magnetic only d) principal and angular momentum e) angular momentum and magnetic Section 2 Short answers (points as indicated) (12) 1. Write balanced molecular, complete ionic, and net ionic equations for the reaction of a) Al (s) and FeCl2 (aq) b) H2SO4 (aq) and Ba(OH)2 (aq) c) HClO (aq) and NaOH (aq) (10) 2. 25.0 mL of 0.525 M AgNO3 are added to 25.0 mL of 0.300 M HCl solution. Write a balanced equation for the reaction. What ions are left in solution at the end, and what are their concentrations? (5) 3. The nitrogen pressure at the Venutian surface is 2050 torr and the atmosphere of Venus is 3.0 mole% N2. What is the surface pressure on Venus in atm? (5) 4. What is the RMS velocity of an ammonia molecule at STP? (6) 5. Use the Kinetic Molecular Theory of Gases to explain why the pressure in a container increases when the volume is reduced at fixed temperature. (8) 6. The value of H for the reaction below is –336 kJ CH4 (g) + 3 Cl2 (g) → CHCl3 (l) + 3 HCl (g) Calculate the heat released to the surroundings when 23.0 g of HCl are formed. (8) 7. 52.5 g of Mg at a temperature of 98.5°C are added to 50.0 g of water at 21.7°C in a coffee cup calorimeter. What is the final temperature? (Cs=1.024 J/g°C for Mg, Cs=4.184 J/g°C for H2O) (8) 8. 10.5 g of KBr(s) at 24.2C is added to 125 g of H2O also at 24.2C in a coffee cup calorimeter. After all the KBr has dissolved the final temperature is 21.1C. Calculate the enthalpy change for dissolving this amount of the salt in J, and kJ per mole of salt. Take the specific heat capacity of the combined solution as 3.90 J/g.C and assume no heat is lost to the surroundings. (8) 9. Given the following reactions: C(s) + O2(g) → CO2(g) H1 = -393.5 kJ H2(g) + ½ O2(g) → H2O(l) H2 = -285.8 kJ C4H6(g) + 5½ O2(g) → 3 H2O(l) + 4 CO2(g) H3 = -2540.2 kJ Find H for the reaction below: 4 C(s) + 3 H2(g) → C4H6(g) (8) 10. The longest wavelength light able to cause the release of a photoelectron from sodium metal is 452 nm. What is the workfunction (energy to remove an electron) of sodium in J? (8) 11. The visible emission spectrum of hydrogen involves lines ending in n f=2. What is ni for the line at 434 nm? (8) 12. Indicate in each case whether the following sets of quantum numbers are permissible for a single electron. If they are not permissible explain what is wrong. a) n=2, ℓ=2, mℓ=1 b) n=0, ℓ=0, mℓ=0 c) n=3, ℓ=2, mℓ=-2 d) n=4, ℓ=2, mℓ=-3