Chem 1041 General Chemistry II Exam 3 Version P - November 18, 2024 PDF

Summary

This is a past exam paper for General Chemistry II, covering topics such as thermodynamics, redox reactions, and electrochemistry. The exam was administered on November 18, 2024.

Full Transcript

**CHEM 1041---General Chemistry II Exam 3 Version P November 18, 2024** **Name\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Section\_\_\_\_\_\_\_\_\_\_\_** **Answer all the questions on the Scantron sheet using a \#2 pencil. You may w...

**CHEM 1041---General Chemistry II Exam 3 Version P November 18, 2024** **Name\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_Section\_\_\_\_\_\_\_\_\_\_\_** **Answer all the questions on the Scantron sheet using a \#2 pencil. You may write in the exam booklet, but you must turn all the pages of the booklet in with your answer sheet.** **Fill out the identifying information on the Scantron sheet (your M-number, section and test version, your name: lastname\firstname). Bubble every character (including the space).** **You may have four items on your desk: (non-graphing) calculator; pencil; test booklet; Scantron Sheet.** **Wait for the signal to begin working on the test. You will have 55 minutes.** **Version P** **\ ** **\ CHEM 1041 General Chemistry II Exam 3P November 18, 2024** **Name\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_M-number\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** 1. Which of the following is true for pure O~2~(*g*) at 25^o^C? A. ∆*G*^o^~f~ \< 0 B) ∆*H*^o^~f~ \> 0 C) *S*^o^ \> 0 D) ∆*H*^o^~f~ \< 0 2. Which of the following is necessary for a process to be thermodynamically favorable? A. ∆*S*~sys~ \> 0 B) ∆*S*~surr~ \< 0 C) ∆*H*~sys~ \< 0 D) ∆*S*~univ~ \> 0 3. Which of the following is always true for an endothermic process? A. *q*~sys~ \> 0, ∆*S*~surr~ \< 0 B. *q*~sys~ \> 0, ∆*S*~surr~ \> 0 C. *q*~sys~ \< 0, ∆*S*~surr~ \< 0 D. *q*~sys~ \< 0, ∆*S*~surr~ \> 0 4. Which statement best describes ∆*S*^o^ for the following reaction? Pb(*s*) + Cl~2~(*g*) → PbCl~2~(*s*) A. ∆*S*^o^ [≅]{.math.inline} 0 B) ∆*S*^o^ = ∆*H*^o^/T C) ∆*S*^o^ \< 0 D) ∆*S*^o^ \> 0 5. Which statement best describes ∆*S*^o^ for the following reaction? 2 NH~3~(*g*) + 2 ClF~3~(*g*) → 6 HF(*g*) + N~2~(*g*) + Cl~2~(*g*) A. ∆*S*^o^ [≅]{.math.inline} 0 B) ∆*S*^o^ = ∆*H*^o^/T C) ∆*S*^o^ \< 0 D) ∆*S*^o^ \> 0 6. Which one of the following changes of state increases the entropy of the system? A. freezing B. condensation C. crystallization D. sublimation 7. Calculate ∆*S*^o^ for the reaction below: Cu(*s*) + 2 HCl(*g*) → CuCl~2~(*s*) + H~2~(*g*) *S*^o^ (J/mol-K) 33 187 108 131 A. −168 J/K-mol~rxn~ B. −19 J/K-mol~rxn~ C. +19 J/K-mol~rxn~ D. +168 J/K-mol~rxn~ 8. For a chemical reaction to be thermodynamically favorable only at high temperatures, which of the following conditions must be met? A. ∆*H*^o^ \< 0, ∆*S*^o^ \> 0 B. ∆*H*^o^ \> 0, ∆*S*^o^ \< 0 C. ∆*H*^o^ \> 0, ∆*S*^o^ \> 0 D. ∆*H*^o^ \< 0, ∆*S*^o^ \< 0 9. For a chemical reaction to be thermodynamically favorable at all temperatures, which of the following conditions must be met? A. ∆*H*^o^ \< 0, ∆*S*^o^ \> 0 B. ∆*H*^o^ \> 0, ∆*S*^o^ \< 0 C. ∆*H*^o^ \> 0, ∆*S*^o^ \> 0 D. ∆*H*^o^ \< 0, ∆*S*^o^ \< 0 10. The Second Law of Thermodynamics tells us that\... A. the universe proceeds toward a state of higher entropy B. the entropy of the universe is constant C. entropy is neither created nor destroyed D. the universe proceeds toward a state of lower entropy 11. Elemental boron can be made by the reaction of boron trichloride (BCl~3~) with hydrogen (H~2~) in a reaction represented by the chemical equation below: BCl~3~(*g*) + 3/2 H~2~(*g*) → B(*s*) + 3 HCl(*g*) ∆*G*^o^~f~ (kJ/mol) −389 0 0 −95 Calculate ∆*G*^o^~rxn~ for this process. A. −674 kJ/mol~rxn~ B) −104 kJ/mol~rxn~ C) +104 kJ/mol~rxn~ D) +294 kJ/mol~rxn~ 12. Consider the reaction represented by the equation below: CuI(*s*) [⇄]{.math.inline} Cu^+^(*aq*) + I^−^(*aq*) A. [ − 68 *kJ*/mol~rxn~]{.math.inline} B) [ − 34 *kJ*/mol~rxn~]{.math.inline} C) [34 *kJ*/mol~rxn~]{.math.inline} D) [68 *kJ*/mol~rxn~]{.math.inline} 13. When the following redox equation is balanced in [acid solution] with the smallest whole number coefficients, what will be the coefficient of Zn(*s*). Zn(*s*) + ReO~4~^−^(*aq*) → Zn^2+^(*aq*) + Re(*s*) A. 2 B) 7 C) 8 D) 16 14. Consider the following redox equation in [basic solution]: Mn(OH)~2~(*s*) + MnO~4~^−^(*aq*) → MnO~4~^2−^(*aq*) A. 4, reactant B) 6 , reactant C) 4, product D) 6, product 15. Which of the following statements about voltaic and electrolytic cells is correct? A. The anode will always gain weight in a voltaic cell. B. Oxidation occurs at the cathode in both cells. C. The electrons flow in the external circuit from the cathode to the anode in both cells. D. The standard Gibbs free energy change is always negative for a voltaic cell. 16. A voltaic cell prepared using aluminum and nickel has the following cell notation: Al(*s*) \| Al^3+^(*aq*) \|\| Ni^2+^(*aq*) \| Ni(*s*) Which of the following reactions occurs at the anode? A. Al(*s*) → Al^3+^(*aq*) + 3e^−^ B. Al^3+^(*aq*) + 3e^−^ → Al(*s*) C. Ni(*s*) → Ni^2+^(*aq*) + 2e^−^ D. Ni^2+^(*aq*) + 2e^−^ → Ni(*s*) 17. A voltaic cell prepared using zinc and iodine has the following cell notation: Zn(*s*) \| Zn^2+^(*aq*) \|\| I^−^(*aq*) \| I~2~(*s*) \| C(graphite) A. Zn^2+^(*aq*) + 2I^−^(*aq*) → Zn(*s*) + I~2~(*s*) B. Zn^2+^(*aq*) + I~2~(*s*) → Zn(*s*) + 2I^−^(*aq*) C. Zn(*s*) + 2I^−^(*aq*) → Zn^2+^(*aq*) + I~2~(*s*) D. Zn(*s*) + I~2~(*s*) → Zn^2+^(*aq*) + 2I^−^(*aq*) 18. What is the *E*^o^~cell~ for the voltaic cell represented by the combination of the following half-reactions? 2Hg^2+^(*aq*) + 2e^−^ [⇄]{.math.inline} Hg~2~^2+^(*aq*) *E*^o^ = 0.92 V Cr^3+^(*aq*) + 3e^−^ [⇄]{.math.inline} Cr(*s*) *E*^o^ = −0.74 V A. 4.24 V B) 1.66 V C) 1.28 V D) 0.18 V 19. What is the *E*^o^~cell~ for the voltaic cell represented by the combination of the following half-reactions? ClO~4~^−^ + 8H^+^ + 8e^−^ [⇄]{.math.inline} Cl^−^ + 4 H~2~O *E*^o^ = 1.39 V VO~2~^+^ + 2H^+^ + 2e^−^ [⇄]{.math.inline} VO^+^ + H~2~O *E*^o^ = 0.99 V A. −2.38 V B. −0.40 V C. +0.40 V D. +2.38 V 20. Examine the following half-reactions and select the strongest oxidizing agent among the substances: PtCl~4~^2−^ + 2e^−^ [⇄]{.math.inline} Pt + 4 Cl^−^ *E*^o^ = 0.76 V RuO~4~ + 8H^+^ + 8e^−^ [⇄]{.math.inline} Ru + 4 H~2~O *E*^o^ = 1.04 V A. PtCl~4~^2−^ B. Pt C. RuO~4~ D. Ru 21. Calculate *E*^o^ and indicate whether the following cell reaction is thermodynamically favorable: 2Cr + 3I~2~ → 2Cr^3+^ + 6I^−^ I~2~ + 2e^−^ [⇄]{.math.inline} 2I^−^ *E*^o^ = 0.53 V Cr^3+^ + 3e^−^ [⇄]{.math.inline} Cr *E*^o^ = −0.74 V A. 1.27 V, favorable B. 1.27 V, unfavorable C. −1.27 V, favorable D. −1.27 V, unfavorable 22. Calculate *E*^o^ and indicate whether the following cell reaction is thermodynamically favorable: 2Fe^3+^ +2H~2~O → H~2~O~2~ + 2H^+^ + 2Fe^2+^ H~2~O~2~ + 2H^+^ + 2e^−^ [⇄]{.math.inline} 2H~2~O *E*^o^ = 1.77 V Fe^3+^ + e^−^ [⇄]{.math.inline} Fe^2+^ *E*^o^ = 0.77 V A. 1.00 V, thermodynamically favorable B. 1.00 V, thermodynamically unfavorable C. −1.00 V, thermodynamically favorable D. −1.00 V, thermodynamically unfavorable 23. Consider the reaction in the lead-acid cell: Pb + PbO~2~ + 2H~2~SO~4~ → 2PbSO~4~ + 2H~2~O *E*^o^ = 2.04 V at 298 K Calculate ∆*G*^o^ for this reaction. A. −197 kJ/mol~rxn~ B. −394 kJ/mol~rxn~ C. −590 kJ/mol~rxn~ D. −787 kJ/mol~rxn~ 24. Calculate *E*^o^~cell~ for the reaction of cadmium metal with nickel(II) ions at 25^o^C, if the equilibrium constant for this reaction is [*K* = 1.2 × 10^5^]{.math.inline}. Ni^2+^ + Cd [⇄]{.math.inline} Ni + Cd^2+^ A. 0.10 V B) 0.15 V C) 0.20 V D) 0.30 V 25. What mass of copper will be deposited when 18.2 amps are passed through a CuSO~4~ solution for 45.0 minutes? (***M***~Cu~ = 63.5 g/mol) A. 0.27 g B) 16.2 g C) 32.4 g D) 162 g **\ ** **Chapter 20 Equations** \ [*S* = *k*ln *W*]{.math.display}\ \ [\$\${\\mathrm{\\Delta}S}\_{\\text{process}} = \\frac{q\_{\\text{reversible}}}{T}\$\$]{.math.display}\ [*ΔS*~universe~ = *ΔS*~surroundings~ + *ΔS*~system~ \> 0]{.math.inline} for thermodynamically favorable processes [*ΔG*~rxn~^^∘^^ \ 0]{.math.display}\ [ \ \ 0]{.math.display}\ [ \> 0]{.math.display}\ [ \> \>]{.math.display}\ [Only *ΔS*]{.math.display}\ \ \ \ Low *T* \ [ \

Use Quizgecko on...
Browser
Browser