What is the composition of the electrolyte in a lead-acid storage cell?

• A. Concentrated sulfuric acid
• B. Dilute sulfuric acid
• C. Both A and B
• D. Tap water

Answer: (C)

The electrolyte in a lead-acid storage cell is composed primarily of dilute sulfuric acid. This composition is crucial for the chemical reactions that occur within the battery during charging and discharging processes. When a lead-acid battery is charged, lead dioxide (PbO2) and sponge lead (Pb) react with the sulfuric acid electrolyte, generating lead sulfate (PbSO4) and water.

Dilute sulfuric acid provides the necessary ions for these reactions to occur efficiently. If the sulfuric acid were concentrated, it could lead to issues such as increased corrosion of the electrodes and reduced battery efficiency.

Therefore, stating that both concentrated sulfuric acid and dilute sulfuric acid could be correct does not accurately represent the typical operational conditions for lead-acid batteries, which predominantly utilize a diluted mixture. Tap water is not a suitable electrolyte for a lead-acid cell, as it would not provide the necessary ionic conductivity or support the electrochemical reactions required for effective battery performance.