结构推理
写出下列电池两个电极的半电池反应，并指出哪个是正极哪个是负极？25°C时电池电动势多少?
(1)Pt,H2(100kPa)?HCl(1.00′10-4mol×L-1)HCl(1.00′10-1mol×L-1)?H2(100kPa),Pt
(2)Pb?Pb(NO3)2(0.20mol×L-1)CuSO4(0.05mol×L-1)?Cu
(已知=0,=-0.13V,=0.34V)
【正确答案】(1)正级:2H++2e-H2负极:H22H++2e-
E+===-0.059V
E-==-0.236V
E电池＝E+-E-=-0.059V-(-0.236)V=0.18V
(2)正极Cu2++2e-Cu;负极PbPb2++2e-
E+=0.34V+=0.30V
E-=-0.13V+=-0.15V
E电池=0.30V-(-0.15)V=0.45V
【答案解析】