The electrolyte of a nickel-cadmium battery is highest when the battery is __________.

The electrolyte of a nickel-cadmium battery is highest when the battery is __________.

• A. In a fully charged condition
• B. In a discharged condition
• C. Resting
• D. Overheated

Answer: (A)

The electrolyte density changes with state of charge because the chemical reactions in a NiCd cell move ions in and out of the solution. The electrolyte is a potassium hydroxide (KOH) solution, and when the cell is fully charged, more ions remain dissolved in the electrolyte rather than forming solid compounds on the electrodes. That higher concentration of dissolved species makes the electrolyte denser (higher specific gravity). During discharge, these ions are drawn into solid hydroxide compounds on the electrodes, reducing the amount dissolved in the solution and lowering density. Temperature effects also play a role (density decreases with higher temperature), so overheating would lower density rather than raise it. Therefore, the electrolyte density is highest when the battery is fully charged.

The electrolyte density changes with state of charge because the chemical reactions in a NiCd cell move ions in and out of the solution. The electrolyte is a potassium hydroxide (KOH) solution, and when the cell is fully charged, more ions remain dissolved in the electrolyte rather than forming solid compounds on the electrodes. That higher concentration of dissolved species makes the electrolyte denser (higher specific gravity). During discharge, these ions are drawn into solid hydroxide compounds on the electrodes, reducing the amount dissolved in the solution and lowering density. Temperature effects also play a role (density decreases with higher temperature), so overheating would lower density rather than raise it. Therefore, the electrolyte density is highest when the battery is fully charged.