In this engaging SciShow experiment, host Hank Green delves into the classic yet often misunderstood science experiment: the lemon battery. Despite popular belief, the electricity isn’t actually in the lemon itself but results from a chemical reaction between zinc and copper, facilitated by the citric acid in the lemon juice.
To start, Hank demonstrates how to prepare the lemon by rolling it to break up the juice packets inside. He then inserts a galvanized nail (coated in zinc) on one side and a copper wire on the other. Connecting a voltmeter to these metals reveals an electric current, but the real question is why this happens.
Hank explains that an electrochemical cell, or battery, requires two electrodes and one electrolyte. In this case, zinc acts as the anode, and copper as the cathode, with the citric acid in the lemon juice serving as the electrolyte. The zinc loses electrons, which then travel through the wire to the copper, creating an electric current.
The lemon juice plays a crucial role by allowing protons (hydrogen ions) to move into the solution, enabling the zinc to lose electrons. These electrons then move to the copper, which prefers having them due to its higher electronegativity. The result is the formation of hydrogen gas and the flow of electricity.
For a more powerful demonstration, Hank shows that inserting multiple sets of nails and wires into the same lemon can increase the electric current, proving that the power lies in the zinc, not the lemon.
This insightful experiment underscores the importance of understanding the science behind seemingly simple phenomena and encourages viewers to explore further.
Creators:
- Hank Green
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