CH 102 1st EditionExam # 4 Study Guide 1. Which of the following processes have a value for ΔS > 0?a. CH3OH(l) → CH3OH(s)b. N2(g) + 3 H2(g) → 2 NH3(g)c. CH4(g) + H2O (g) → CO(g) + 3 H2(g)d. Na2CO3(s) + H2O(g) + CO2(g) → 2 NaHCO3(s)e. All of the above processes have a value for ΔS > 0.2. Which of the following statements is TRUE?a. Entropy is not a state function.b. Endothermic processes are never spontaneous.c. Exothermic processes are always spontaneous.d. Endothermic processes decrease the entropy of the surroundings, at constant T and P.e. None of the above is true.3. Consider a reaction that has a negative value of ΔH and a positive value of ΔS. Which of the following statements is TRUE?a. This reaction will be spontaneous only at high temperatures.b. This reaction will be spontaneous at all temperatures.c. This reaction will be nonspontaneous at all temperatures.d. This reaction will be nonspontaneous only at high temperatures.e. It is not possible to determine without more information.4. Identify the compound that is NOT an allotrope of carbon.a. diamondb. graphitec. dry iced. carbon nanotubese. Buckminster fullerene5. Calculate ΔS°rxn for the following reaction. The value of S° for each species is given in the table at the end of this exam.C2H2(g) + 2 H2(g) → C2H6(g)ΔS°rxn = -233.1 J/mol∙K6. What can change the direction of a reversible reaction?a. change in temperatureb. change in pressurec. change in volumed. none of the abovee. all of the above7. For the following reaction ΔH°= -158.0 kJ/mol and ΔS°= -219.9 J/mol∙K HCN(g) + 2 H2(g) → CH3NH2(g)Estimate ΔGrxn for the reaction at 387 K. ΔGrxn = -77.8 kJ/mol8. Calculate the value of ΔG°rxn for the following reaction using values of ΔHf° and S° found in the table at the endof this exam. Remember, under standard conditions the temperature is 25 °C.4 HNO3(g) + 5 N2H4(l) → 7 N2(g) + 12 H2O(l)ΔH°rxn = -4510.6 kJ/molΔS°rxn = +991.2 J/mol∙KΔG°rxn = -4806.0 kJ/mol9. Phosphorous and chlorine gases combine to produce phosphorous trichloride:P2 (g) + 3 Cl2 (g) → 2PCl3 (g)ΔG° at 298 K for this reaction is -642.9 kJ/mol. What is the value of ΔG at 298 K for a reaction mixture that consists of 1.5 atm P2, 1.6 atm Cl2, and 0.65 atm PCl3?∆ Grxn=∆ G0−RTlnQ=−642.9kJmol−(8.3144 Jmol ∙ K)(298 K)ln((0.65)2(1.5) (1.6)3)=−636.3kJ /mol10. Reduction is an electrochemical process wherea. electrons are given to a chemical speciesb. electrons are taken from a chemical speciesc. protons react with a base to make a conjugate acidd. neutrons are evolved by radioactive decaye. solar radiation is converted to electrical power.11. In an electrochemical cell what process occurs at the anode?a. oxidationb. hydrogenationc. hydrolysisd. reductione. nuclear decay12. An electrochemical cell has one half-cell consisting of an aluminum electrode in a 1 M aluminum nitrate electrolyte. The other half cell consists of a platinum electrode in a 1 M solution of platinum(II) nitrate electrolyte. What is the standard potential for this electrochemical cell?Al3+ + 3 e- → Al (s) E° = -1.66 VPt2+ + 2 e- → Pt (s) E° = +1.19 VE° = +2.85 V13. An electrochemical cell has one half-cell consisting of an aluminum electrode in a 1.05 x 10-2 M aluminum nitrate electrolyte. The other half cell consists of a platinum electrode in a 0.557 M solution of platinum nitrate electrolyte. What is the potential for this electrochemical cell?Al3+ + 3 e- → Al (s) E° = -1.66 VPt2+ + 2 e- → Pt (s) E° = +1.19 VNet electrochemical reaction3 Pt2+ (aq) + 2 Al (s) → 3 Pt (s) + 2 Al3+ (aq)3+¿Al¿¿¿2¿2+¿Pt¿¿¿2¿¿¿E=E0−RTnFln¿14. A metal spoon was silver plated by the electrolytic reduction of Ag+ to silver metalAg+ (aq) + 1 e- → Ag (s)If a 1.25 A current was applied for 90.0 seconds, how many grams of Ag metal were plated on the spoon?126 mg AgUseful InformationGas Constant, R 0.08205746 L atm/mol KGas Constant, R 8.3144621 J/mol KFaraday Constant 96,485 C/molUseful Thermodynamic DataCompound ΔHf° (kJ/mol) S° (J/mol·K)C2H2(g) 200.9H2(g) 130.7C2H4(g) 219.3C2H6(g) 229.2HNO3+207.0 146.0NO(g) +91.3 210.8NO2(g) +33.2 240.1H2O(l) -285.8 70.0N2H4(l) +50.6 121.2N20