QQuestionChemistry
QuestionChemistry
Why do positive ions gain electrons at the cathode, and why is this not possible at the anode?
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Step 1:I'll solve this electrochemistry problem step by step, following the specified LaTeX formatting guidelines:
Step 2:: Understanding Ion Movement in Electrolysis
Positive ions (cations) move towards the negatively charged electrode during electrolysis. The cathode is the negatively charged electrode that attracts positive ions.
Step 3:: Electron Transfer Mechanism
- $$e^{-}$$ represents electrons
At the cathode, positive ions gain electrons through reduction. This process can be represented by the general reduction half-reaction: Where:
Step 4:: Energy Considerations at the Cathode
The cathode provides free electrons that have lower energy than the electrons in the positive ion. This energy difference allows electrons to be transferred to the positive ion, neutralizing it.
Step 5:: Why Electron Gain Occurs at the Cathode
- The cathode is negatively charged - Negative charge attracts positive ions - Excess electrons are available at the cathode - Reduction potential is favorable at this electrode
Step 6:: Why Electron Gain is Not Possible at the Anode
At the anode: - The electrode is positively charged - Positive charge repels positive ions - Electrons are being removed (oxidation occurs) - No excess electrons are available for positive ions to gain
Final Answer
At the anode, the opposite occurs - electrons are being removed, preventing positive ions from gaining electrons.
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