Left(so as to decrease the pressure as per le Chatelier's principle). Part B.Answer any five of the eight questions(CI-C8).If you answer more than five,the best five will be used to calculate your mark (20 marks each). B1.(a)Aluminum metal is produced by the reduction of aluminum ions in a molten solution according to Al+3eAl What mass of aluminum metal can be produced using a current of 100,000 A over a period of8 hours? t105C1s(8hx3600sh-=29,849mole n-F 96487C(mol e-)-1 but each mole of Al requires 3 moles of the electrons to be reduced to the metal.Thus,the number of moles of Al produced in this time is 29.849/3=9950 moles Als Mass Al(s)27.0 g mol"x 9950 mol 2.69 x 105g=269 kg B1.(b)For the galvanic reaction+CZnCa 50C.calculate the cell potential (in Volts)if [Cd"]=0.068 M and [Zn]=1.00 M. E°=-0.40V+0.76V=+0.36V Q=IZn"1.00M ICd10.069M=14.7 T=50℃+273=323K E=Er-Rno=038v.8aaenCg23 2(96487Cmo') =0.32V 2Left (so as to decrease the pressure as per le Chatelier’s principle). Part B. Answer any five of the eight questions (C1 – C8). If you answer more than five, the best five will be used to calculate your mark (20 marks each). B1. (a) Aluminum metal is produced by the reduction of aluminum ions in a molten solution according to Al+3 (l) + 3 e⎯ → Al(l). What mass of aluminum metal can be produced using a current of 100,000 A over a period of 8 hours? 5 1 1 it 10 C/ s(8h 3600sh ) n 2 F 96487C(mol e ) − 9,849 mol e− − − × = = = but each mole of Al+3 requires 3 moles of the electrons to be reduced to the metal. Thus, the number of moles of Al(s) produced in this time is 29,849 / 3 = 9950 moles Al(s). Mass Al(s) = 27.0 g mol-1 x 9950 mol = 2.69 x 105 g = 269 kg B1. (b) For the galvanic reaction Zn(s) + Cd+2 (aq) → Zn+2 (aq) + Cd(s) at 50o C, calculate the cell potential (in Volts) if [Cd+2 (aq)] = 0.068 M and [Zn+2 (aq)] = 1.00 M. Eo = -0.40 V + 0.76 V = +0.36 V 2 (aq) 2 (aq) [Zn ] 1.00M Q 1 [Cd ] 0.068M + + = == 4.7 T = 50o C + 273 = 323 K 1 1 o 1 RT 8.314JK mol (323K) E E ln(Q) 0.36V nF 2(96487C mol ) 0.32 V − − − =− = − = 2