In the electrolysis of a CuCl₂ solution using Cu electrodes, if the weight of the cathode increased by 2 grams, what happened at the anode?
Correct answer: D. 2 grams of copper goes into the solution as Cu²⁺
- A. 0.2 mole of Cu²⁺ will go into the solution
- B. 560 ml O₂ is liberated
- C. No loss in weight
- D. 2 grams of copper goes into the solution as Cu²⁺
Explanation
When using active electrodes (copper), the anode is oxidized:Cu(s)→ Cu²⁺(aq)+ 2e⁻. The cathode is where reduction occurs: Cu²⁺(aq) + 2e⁻ → Cu(s). For every mole of copper that plates onto the cathode, one mole of copper must dissolve from the anode. Therefore, the mass loss at the anode is equal to the mass gain at the cathode.
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Electrochemistry describes electron transfer through oxidation and reduction, identifies oxidizing and reducing agents, and applies oxidation numbers to balance redox equations. It also covers electrode potential and the standard hydrogen electrode, which provides the reference for comparing the reduction tendencies of other electrodes.
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