CH Practice Exam #2

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1 H Practice xam #2 Multiple hoice - hoose the best answer and place the letter corresponding to the answer in the space provided. 1. Give the direction of the reaction, if K << 1. ) The forward reaction is favored. ) The reverse reaction is favored. ) Neither direction is favored. ) If the temperature is raised, then the forward reaction is favored. ) If the temperature is raised, then the reverse reaction is favored.. 2. The equilibrium constant is given for one of the reactions below. etermine the value of the missing equilibrium constant. H2(g) + r2(g) 2 Hr (g), Kc = Hr(g) H2(g) + r2(g) Kc =? ) ) ) ) ) What is Δn for the following equation in relating Kc to Kp? SO3(g) + NO(g) SO2(g) + NO2(g) ) 0 ) -1 ) -2 ) 2 ) 1 4. etermine the value of Kc for the following reaction if the equilibrium concentrations are as follows: [N2]eq = 1.5 M, [H2]eq = 1.1 M, [NH3]eq = 0.47 M. N2(g) + 3 H2(g) 2 NH3(g) ) 3.5 ) 0.28 ) 9.1 ) 0.11 ) Which of the following statements is TRU? ) If Q < K, it means the reverse reaction will proceed to form more reactants. ) If Q > K, it means the forward reaction will proceed to form more products. ) If Q = K, it means the reaction is at equilibrium. ) ll of the above are true. ) None of the above are true.

2 6. onsider the following reaction at equilibrium. What effect will adding more SO3 have on the system? SO2(g) + NO2(g) SO3(g) + NO(g) ) The reaction will shift to the left. ) No change will be observed. ) The equilibrium constant will decrease. ) The equilibrium constant will increase. ) The reaction will shift in the direction of products. 7. alculate P (NO)eq, if P (NOl)eq = 0.33 atm, P (l2)eq = 0.50 atm, and Kp = 1.9 x NOl(g) 2 NO(g) + l2(g) ) 1.7 atm ) atm ) 0.30 atm ) atm ) atm 8. onsider the following reaction: Xe(g) + 2 F2(g) XeF4(g) reaction mixture initially contains 2.24 atm Xe and 4.27 atm F2. If the equilibrium pressure of Xe is 0.34 atm, find the equilibrium constant (Kp) for the reaction. ) 25 ) 0.12 ) 0.99 ) 8.3 ) onsider the following reaction at equilibrium. What effect will removing NO2 have on the system? SO2(g) + NO2(g) SO3(g) + NO(g) ) The reaction will shift in the direction of products. ) The reaction will shift to decrease the pressure. ) No change will occur since SO3 is not included in the equilibrium expression. ) The reaction will shift in the direction of reactants. ) The equilibrium constant will decrease.

3 10. onsider the following reaction at equilibrium. What effect will increasing the pressure of the reaction mixture have on the system? us(s) + O2(g) u(s) + SO2(g) ) The equilibrium constant will decrease. ) No effect will be observed. ) The reaction will shift to the right in the direction of products. ) The equilibrium constant will increase. ) The reaction will shift to the left in the direction of reactants. 11. The reaction below has a Kc value of What is the value of Kp for this reaction at 200 K? 2 SO2(g) + O2(g) 2 SO3(g) ) ) ) ) ) onsider the following reaction and its equilibrium constant: SO2(g) + NO2(g) SO3(g) + NO(g) Kc = 0.33 reaction mixture contains 0.41 M SO2, 0.14 M NO2, 0.12 M SO3 and 0.14 M NO. Which of the following statements is TRU concerning this system? ) The reaction will shift in the direction of reactants. ) The equilibrium constant will decrease. ) The reaction will shift in the direction of products. ) The reaction quotient will decrease. ) The system is at equilibrium. 13. What is the conjugate base of H2PO4? ) HPO4 2- ) PO4 2- ) H3PO4 ) H3O+ ) OH 14. Identify the weak diprotic acid. ) H3OOH ) HOOH ) H3PO4 ) H2SO4 ) H2O3

4 15. Which of the following solutions would have the highest ph? ssume that they are all 0.10 M in acid at 25º. The acid is followed by its Ka value. ) HF, ) HN, ) HNO2, ) HHO2, ) HlO2, alculate the hydronium ion concentration in an aqueous solution with a poh of ) M ) M ) M ) M ) M 17. etermine the [H3O+] in a M HlO solution. The Ka of HlO is ) M ) M ) M ) M ) M 18. solution with a hydrogen ion concentration of M is and has a hydroxide ion concentration of. ) acidic, M ) acidic, M ) basic, M ) basic, M 19. Which of the following is a STRONG base? ) I- ) NH3 ) H3OH ) NO3 ) LiOH 20. If an equal number of moles of the weak acid HN and the strong base KOH are added to water, is the resulting solution acidic, basic, or neutral? ) acidic ) basic ) neutral ) There is insufficient information provided to answer this question

5 21. alculate the ph of a solution formed by mixing ml of 0.15 M NH4l with ml of 0.20 M NH3. The Kb for NH3 is 1.8 x ) 9.13 ) 9.25 ) 9.53 ) 4.74 ) Which of the following is TRU? ) n effective buffer has a [base]/[acid] ratio in the range of ) buffer is most resistant to ph change when [acid] = [conjugate base] ) n effective buffer has very small absolute concentrations of acid and conjugate base. ) buffer can not be destroyed by adding too much strong base. It can only be destroyed by adding too much strong acid. ) None of the above are true ml sample of 0.10 M NH3 is titrated with 0.10 M HNO3. etermine the ph of the solution after the addition of 50.0 ml of HNO3. The Kb of NH3 is ) 4.74 ) 7.78 ) 7.05 ) 9.26 ) etermine the molar solubility of gr in a solution containing M Nar. Ksp (gr) = ) M ) M ) M ) M ) M 25. The molar solubility of ZnS is M in pure water. alculate the Ksp for ZnS. ) ) ) ) )

6 26. Give the equation for a saturated solution in comparing Q with Ksp. ) Q > Ksp ) Q < Ksp ) Q = Ksp ) Q Ksp ) none of the above 27. Which of the following solutions is a good buffer system? ) solution that is 0.10 M Nal and 0.10 M Hl ) solution that is 0.10 M HN and 0.10 M LiN ) solution that is 0.10 M NaOH and 0.10 M HNO3 ) solution that is 0.10 M HNO3 and 0.10 M NaNO3 ) solution that is 0.10 M HN and 0.10 M KI 28. You wish to prepare an H2H3O2 buffer with a ph of If the pka of H2H3O2 is 4.74, what ratio of 2H3O2 /H2H3O2 must you use? ) 0.10 ) 0.40 ) 0.40 ) 2.51 ) escribe what happens at neutral ph for aluminum hydroxide. ) l(h2o)6 3+ precipitates ) l(h2o)2(oh)4 - dissolves ) l(oh)3 precipitates ) l precipitates ) l dissolves 30. Which of the following processes has (have) a ΔS > 0? ) H3OH(l) H3OH(s) ) N2(g) + 3 H2(g) 2 NH3(g) ) H4(g) + H2O(g) O(g) + 3 H2(g) ) Na2O3(s) + H2O(g) + O2(g) 2 NaHO3(s) ) ll of the above processes have a ΔS > onsider a reaction that has a positive ΔH and a positive ΔS. Which of the following statements is TRU? ) This reaction will be spontaneous only at high temperatures. ) This reaction will be spontaneous at all temperatures. ) This reaction will be nonspontaneous at all temperatures. ) This reaction will be nonspontaneous only at high temperatures.

7 32. elow what temperature does the following reaction become nonspontaneous? 2 HNO3(aq) + NO(g) 3 NO2(g) + H2O(l) ΔH = kj; ΔS = J/K ) 39.2 K ) 151 K ) 475 K ) This reaction is nonspontaneous at all temperatures. ) This reaction is spontaneous at all temperatures. 33. alculate ΔS rxn for the following reaction. The S for each species is shown below the reaction. N2H4(l) + H2(g) 2 NH3(g) S (J/mol K) ) J/K ) J/K ) J/K ) J/K ) J/K 34. stimate ΔG rxn for the following reaction at 825 K. 2 Hg(g) + O2(g) 2 HgO(s) ΔH = kj; ΔS = J/K ) kj ) -37 kj ) +37 kj ) +645 kj ) -645 kj 35. etermine the equilibrium constant for the following reaction at 298 K. l(g) + O3(g) lo(g) + O2(g) ΔG = kj ) ) ) ) )

8 a + b c + d Kw =[H3O+][OH-]=1.0 x Kw/[OH-]= [H3O+] Kw/[H3O+]= [OH-] ph = -log[h3o+] poh = -log[oh-] pka = -logka Ka = Kw/Kb Kb = Kw/Ka Δ = q + w Δ = ΔH + PΔV is a state function eat has S univ = S sys + S surr > 0 ΔS rxn = ΔS sys = S final S initial ΔSº rxn = Σn products Sº products Σn reactants Sº reactants ΔGº reaction = ΔHº reaction - TΔSº reaction ΔGº rxn = 0, and Q = K ΔG rxn = RT ln K (K = e ΔG/RT )

CH Practice Exam #2

CH Practice Exam #2 CH1810 - Practice Exam #2 Part I - Multiple Choice - Choose the best answer and place the letter corresponding to the answer in the space provided. 1. Consider the following reaction and its equilibrium