When an acid cell is charged then :

Question

When an acid cell is charged then : (A) voltage of cell increases (B) electrolyte of cell dilutes (C) resistance of cell increases (D) none of the above

Tardigrade Admin · Accepted Answer

The discharged acid cell (lead storage battery or cell) can be recharged by passing a direct current through it in opposite direction. During recharging of cell, the electrode material are restored in their original forms. Due to formation of

H^{+}

and

S O_{4}^{2 -}

ions the specific gravity of sulphuric acid increases and it attains the original value

(1.3 g / c m^{3})

and also its EMF (voltage) increases.
During charging
At negative electrode :

P b S O_{4} (s) + 2 e^{-} direct current P b (s) + S O_{4}^{2 -} (a q)

At positive electrode :

P b S O_{4} (s) + 2 H_{2} O current direct

P b O_{2} (s) + 4 H^{+} (a q) + S O_{4}^{2 -} (a q) + 2 e^{-}

overall charging reaction :

2 P b S O_{4} (s) + 2 H_{2} O Charging electrode materials recovered P b (s) + P b O_{2} (s)

+ H_{2} S O_{4} reformed 4 H^{+} (a q) + S O_{4}^{2 -} (a q)

overall reaction during charging :

P b (s) + P b O_{2} (s) + 4 H^{+} (a q) + 2 S O_{4}^{2 -} (a q) ⟶ 2 P b S O_{4} (s) + 2 H_{2} O

Q. When an acid cell is charged then :

voltage of cell increases

electrolyte of cell dilutes

resistance of cell increases

none of the above