Physical chemistr lectrochemistry (4) Xuan Cheng Xiamen University
1 Electrochemistry(4) Xuan Cheng Xiamen University Physical Chemistry
pp pical chemistry ectrochemid四 QUIZ (3 points each) (15分) Given that AGo=-2127 kJ. mol-l for the cell reaction in the Daniel cell at 25C and that m( cuso4 =10×103 molkg and m(ZnSO4)=3.0×103 mol kg, calculate (1)the ionic strength of the solutions (2 )the mean ionic activity coefficients in the respective compartments ()the reaction quotient (4)the standard cell potential (5)the cell potential (take y+=Y=y+ in the respective compartments
2 Given that rGo = -212.7 kJmol-1 for the cell reaction in the Daniel cell at 25℃ and that m(CuSO4 ) = 1.010-3 molkg-1 and m(ZnSO4 ) = 3.010-3 molkg-1 , calculate (1) the ionic strength of the solutions (2) the mean ionic activity coefficients in the respective compartments (3) the reaction quotient (4) the standard cell potential (5) the cell potential Physical Chemistry Electrochemistry QUIZ (3 points each) (15分) (take + = - = ± in the respective compartments)
pp pical chemistry ectrochemid四 QUIZ Answers 1=-∑mz (1分) for cuso solution 2 0×103×2+(-2)=40×103m01-kg(1分) for zn so∠ solution 0×10~3×2+(-2 1.2×10ml.h-1 (1分)
3 Answers. (a) for CuSO4 solution for ZnSO4 solution Physical Chemistry Electrochemistry QUIZ = 2 2 1 I mz ( ) 3 2 2 3 1 1.0 10 2 ( 2) 4.0 10 2 1 − − − I = + − = mol k g ( ) 3 2 2 2 1 3.0 10 2 ( 2) 1.2 10 2 1 − − − I = + − = mol k g (1分) (1分) (1分)
pp pical chemistry ectrochemid四 QUIZ Answers b) in very dilute aqueous solution at25°C(1分) /2 hny±=0.5102+|=-Vm/m /2 hny±(CO4)=-0.510×2×|-2140×103/1 y(CuSO4=0.74(1分) /2 hny(ZhSO4)=-0.510×2×|-211.2×10-2/ y4(znSo4=0.60(1分)
4 Answers. Physical Chemistry Electrochemistry QUIZ (b) in very dilute aqueous solution at 25℃ ( ) 1/ 2 ln 0.510 | | / o = − z + z − I m m ( ) 1/ 2 3 ln ( 4 ) 0.510 2 | 2| 4.0 10 /1 − CuSO = − − ± (CuSO4 ) = 0.74 ( ) 1/ 2 2 ln ( 4 ) 0.510 2 | 2 | 1.2 10 /1 − ZnSO = − − ± (ZnSO4 ) = 0.60 (1分) (1分) (1分)
pp pical chemistry ectrochemid四 QUIZ Answers (c) The cell reaction:(1分) Cuz+(m1)+ so42(m1)+Zn>Cu+ Zn +(m2 )+so42(m2) SO2 (zn2+) Q=∏a"= ZnSO (SO4 )ZnSO4(SO4 )DmSO4 (ac12 I Sir Q)(cn2+mcn2-)((02) CuSo Ince )m(SO2 )CuSO4 Y+( Cu2+)CuSO 4 =Y (SO4-)CuSO4=Y+( CuSO4)=0.74 Y+(Zn *)ZnSO 4=Y(S042)ZnSO4 =Y+(ZnSO4)=0.60 Also My=m( Cu2+)CuSO4=m(S042)CuSO4=1x10 mo·ka1 m2=m (Zn+)ZnSO4 =m(So4)ZnSO4=3x10-3mol-kgs
5 Answers. Physical Chemistry Electrochemistry QUIZ (c) The cell reaction: Cu2+ (m1 ) + SO4 2- (m1 ) + Zn → Cu + Zn2+ (m2 ) + SO4 2- (m2 ) = = = + + − − + + − − + − + − ( )( ) ( )( ) ( )( ) ( )( ) ( )( ) ( )( ) 4 2 4 4 2 4 2 2 4 2 4 4 2 4 2 2 4 2 4 2 4 2 4 2 ( ) ( ) ( ) ( ) ( ) ( ) CuSO CuSO ZnSO ZnSO CuSO ZnSO Cu Cu SO SO Zn Zn SO SO Cu SO v Zn SO m m m m a a a a Q a Since + (Cu2+)CuSO4 = - (SO4 2- )CuSO4 = ± (CuSO4 ) = 0.74 + (Zn2+)ZnSO4 = - (SO4 2- )ZnSO4 = ± (ZnSO4 ) = 0.60 Also m1 = m (Cu2+)CuSO4 = m (SO4 2- )CuSO4 = 110-3 molkg-1 m2 = m (Zn2+)ZnSO4 = m (SO4 2- )ZnSO4 = 310-3 molkg- 1 (1分) (1分)