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(a) What voltage is calculated for the Daniell element if at 298 K the concentration of the zinc sulphate solution and that of the copper sulphate solution is 1 mol/L each. Please specify the generally applicable equation for this.
(b) Calculate the new voltages assuming that after every 15 minutes the concentrations will decrease by 0.1 mol/L We have changed.
Solution: From the previous exercise can be taken E1 and E2. Also the presentation is simplified a little because the concentration of the solid is 1 mol/l
- (a) It applies from earlier:
· E1(Zn/Zn2+)=-0.76 + 0.059/2·log(c(Zn2+))
· E2(Cu/Cu2+)= 0.35 + 0.059/2·log(c(Cu2+))
· ΔE = E2 – E1
= 0.35 + 0.059/2·log(c(Cu2+)) – (-0.76 + 0.059/2·log(c(Zn2+)))
= 1.11 + 0.059/2 · ( log(c(Cu2+)) -log(c(Zn2+)) )
= 1.11 + 0.059/2 · log(c(Cu2+)/c(Zn2+))
(b) The concentration of copper ion increases, the concentration of zinc increases.
ΔE = 1.11 + 0.059/2 · log(c(Cu2+)/c(Zn2+))c(Cu2+) c(Zn2+) ΔE 1 1.0 1.11 0.9 1.1 1.107 0.8 1.2 1.105 0.6 1.4 1.099 0.4 1.6 1.092 0.2 1.8 1.082 0.001 1.999 1.012 - (a) It applies from earlier:
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