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Curated by: Khan Academy India - English (12 videos)
Let's dive deep into the chemistry of the common AA battery! This video explains the inner workings of a dry cell (Leclanché cell), a type of primary galvanic cell. We'll start with a quick review of galvanic cells and then explore the practical differences between non-rechargeable (primary) and rechargeable (secondary) batteries. You'll learn about the key components of a dry cell—the zinc anode, the carbon cathode, and the electrolyte paste—and see the step-by-step chemical reactions that produce electricity. We'll also briefly cover the mercury cell and answer the crucial question: why can't primary cells be recharged? Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now! https://www.khanacademy.org/science/chemistry/oxidation-reduction 0:00 - Introduction to the Dry Cell (AA Battery) 0:21 - Refresher: The Galvanic Cell 0:50 - Practical Galvanic Cells: Primary vs. Secondary 1:16 - Key Differences between Primary and Secondary Cells 2:05 - Inside a Dry Cell (Leclanché Cell) 2:25 - Anatomy of the Dry Cell 3:02 - Chemical Reactions in a Dry Cell 3:37 - Step 1: Anode Reaction (Zinc Oxidation) 4:41 - Step 2: Electron Flow through the Circuit 5:47 - Step 3: Cathode Reaction (Manganese Dioxide Reduction) 7:14 - Introduction to the Mercury Cell 8:04 - Why Can't a Dry Cell Be Recharged? 9:32 - Comparison: Dry Cell vs. Mercury Cell Khan Academy India is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We have videos and exercises that have been translated into multiple Indian languages, and 15 million people around the globe learn on Khan Academy every month. Support Us: https://india.khanacademy.org/donate Created by Sarath Penumuru