Chapter 19, Problem 67E

Interpretation Introduction

(a)

Interpretation:

Gases released when recharging a lead storage battery should be estimated.

Concept introduction:

When an automobile engine is started, the battery is at first discharged. Once the car is in motion, an alternator powered by the engine constantly recharges the battery. At times, the plates of the battery become coated with $PbS{O}_4$ (s) and the electrolyte becomes sufficiently diluted with water that the battery must be recharged by connecting it to an external electric source. This forces the reverse of a nonspontaneous reaction as follows.

$Pb(s)+Pb{O}_2(s)+2HS{O}_4{}^{-}(aq)+2H^{+}(aq)\to 2PbS{O}_4(s)+2H_{2}O(l)$

Interpretation Introduction

(b)

Interpretation:

Cell reaction should be written to describe the formation of gases when recharging a lead storage battery at too high voltage.

Concept introduction:

When an automobile engine is started, the battery is at first discharged. Once the car is in motion, an alternator powered by the engine constantly recharges the battery. At times, the plates of the battery become coated with $PbS{O}_4$ (s) and the electrolyte becomes sufficiently diluted with water that the battery must be recharged by connecting it to an external electric source. This forces the reverse of a nonspontaneous reaction as follows.

$Pb(s)+Pb{O}_2(s)+2HS{O}_4{}^{-}(aq)+2H^{+}(aq)\to 2PbS{O}_4(s)+2H_{2}O(l)$