🔍 Key Concepts

• Primary cell chemistry – understand what happens at the positive and negative electrodes during discharge • The meaning of polarization vs depolarization in batteries • The role of manganese dioxide in some primary cells (such as dry cells)

💭 Think About

• What physical effect occurs when hydrogen gas bubbles collect on an electrode? Does this help or hinder current flow? • Is polarization a condition/problem in the cell, or is it a chemical added to fix that problem? • How is manganese dioxide involved in the chemical reactions of a dry cell – is it a process, a condition, or a material?

✅ Before You Answer

• Make sure you know that polarization describes a performance problem in the cell, not a specific chemical substance. • Confirm whether depolarization is something that causes hydrogen to form, or something used to deal with hydrogen that has already formed. • Check if manganese dioxide is the gas, the electrode, or a compound used for another purpose in the cell.