20. Electrochemistry
Electroplating
36PRACTICE PROBLEM
Ordinary alkaline battery half-reactions can be written as
anode: Zn(s) + 2 OH−(aq) → Zn(OH)2(s) + 2 e−
cathode: MnO2(s) + H2O(l) + e− → MnO(OH)(s) + OH−(aq)
Consider a hypothetical battery composed of the same anode as the ordinary alkaline battery and a cathode where CoO42− ion from Na2CoO4 is reduced to solid Co(OH)3 in a basic solution. Because the hypothetical battery's cathode can provide more charge per unit mass than an ordinary alkaline battery of the same size and weight, it should last longer. Compare quantitatively the amount of coulombs of charge released when 15.0 g of Na2CoO4 is reduced to Co(OH)3 with the amount of coulombs of charge released when 15.0 g of MnO2 is reduced to MnO(OH).
Ordinary alkaline battery half-reactions can be written as
anode: Zn(s) + 2 OH−(aq) → Zn(OH)2(s) + 2 e−
cathode: MnO2(s) + H2O(l) + e− → MnO(OH)(s) + OH−(aq)
Consider a hypothetical battery composed of the same anode as the ordinary alkaline battery and a cathode where CoO42− ion from Na2CoO4 is reduced to solid Co(OH)3 in a basic solution. Because the hypothetical battery's cathode can provide more charge per unit mass than an ordinary alkaline battery of the same size and weight, it should last longer. Compare quantitatively the amount of coulombs of charge released when 15.0 g of Na2CoO4 is reduced to Co(OH)3 with the amount of coulombs of charge released when 15.0 g of MnO2 is reduced to MnO(OH).