During discharge of a lead storage cell the density of sulphuric acid in the cell :

increasing

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decreasing

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remains unchanged

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initially increases but decreases subsequently

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Solution

The correct option is B decreasing
The lead sulfate $(P b S O_{4})$ is whitish in colour.
During discharging, both of the plates are covered with $P b S O_{4}$ .
The specific gravity of sulfuric acid solution falls due to formation of water during the reaction at $P b O_{2}$ plate.
As a result, the rate of reaction falls which implies the potential difference between the plates decreases during the discharging process.
Hence option B is correct

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Similar questions

Q. During discharge of a lead storage cell, the density of sulphuric acid in the cell:

Q. Write cell reactions in lead storage battery during discharge.

Assertion: The density of

H_{2} S O_{4}

decreases in lead storage cell during discharging.

Reason: Calomel electrode is a reference electrode and it is better than hydrogen electrode.

Q. During the discharge of a lead storage battery, the density of sulphuric acid fell from

1.294

1.139 g m l^{- 1}

. Sulphuric acid of density

1.294 g m l^{- 1}

is 39% by weight and that of density

1.139 g m l^{- 1}

is 20% by weight. The battery holds 3.5 L of the acid and the volume remained practically constant during the discharge. Find the number of ampere-hours for which the battery must has been used.

The charging and discharging reactions are as follows:

$P b + S O_{4}^{2 -} \to P b S O_{4} + 2 e^{-}$ (charging)

$P b O_{2} + 4 H^{\oplus} + S O_{4}^{2 -} + 2 e^{-} \to P b S O_{4} + 2 H_{2} O$ (discharging)

During the discharge of a lead storage battery, the density of sulphuric acid fell from $1.294$ to $1.139$ gm $L^{- 1}$ . Sulphuric acid of density $1.294$ gm $L^{- 1}$ is $39$ % by weight and that of density 1.139 gm $L^{- 1}$ is $20$ % by weight. The battery holds $3.5$ litres of acid and the column practically remained constant during the discharge.

Calculate the number of ampere-hours for which the battery must have been used. The charging and discharging reactions are :

$P b + S O {_{4}}^{2 -} \to P b S O_{4} + 2 e^{-}$ (charging)

$P b O_{2} + 4 H^{+} + S O {_{4}}^{2 -} + 2 e^{-} \to P b S O_{4} + 2 H_{2} O$ (discharging)

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