Which substance commonly serves as the electrolyte in a lead-acid battery?

Which substance commonly serves as the electrolyte in a lead-acid battery?

• A. Water and sulfuric acid
• B. Water and sodium hydroxide
• C. Water and acetic acid
• D. Water and ammonia

Answer: (A)

The key idea is that the electrolyte is the ion-conducting medium that lets charge move between the plates. In a lead-acid battery, that medium is a solution of sulfuric acid in water. The water is the solvent, and sulfuric acid provides the sulfate and hydrogen ions that participate in the chemical reactions at the electrodes and carry current through the liquid. This combination enables the formation and dissolution of lead sulfate on the plates as the battery charges and discharges. Using a different substance, like sodium hydroxide, acetic acid, or ammonia, would not supply the same ion balance or stability needed for the lead plate reactions, and water alone conducts poorly without enough dissolved ions. That’s why the electrolyte in a lead-acid battery is a sulfuric acid solution in water, not those other options.

The key idea is that the electrolyte is the ion-conducting medium that lets charge move between the plates. In a lead-acid battery, that medium is a solution of sulfuric acid in water. The water is the solvent, and sulfuric acid provides the sulfate and hydrogen ions that participate in the chemical reactions at the electrodes and carry current through the liquid. This combination enables the formation and dissolution of lead sulfate on the plates as the battery charges and discharges.

Using a different substance, like sodium hydroxide, acetic acid, or ammonia, would not supply the same ion balance or stability needed for the lead plate reactions, and water alone conducts poorly without enough dissolved ions. That’s why the electrolyte in a lead-acid battery is a sulfuric acid solution in water, not those other options.