This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the answers for question 39: a) The electrode that decreased in mass during electrolysis is the anode (positive electrode). Explanation: At the anode, copper metal is oxidized to copper(II) ions (Cu(s) → Cu^2+(aq) + 2e^-), causing the copper electrode to dissolve into the solution and its mass to decrease. b) Step 1: Write the half-reaction for the deposition of copper. The deposition of copper at the cathode is given by the half-reaction: Cu^2+(aq) + 2e^- → Cu(s) Step 2: Determine the moles of electrons required per mole of copper. From the balanced half-reaction, 2 moles of electrons are required to deposit 1 mole of copper. Step 3: Calculate the total charge. The charge of 1 mole of electrons is 1 Faraday, which is 96500 Coulombs. Therefore, the quantity of charge needed to deposit 1 mole of copper is: Charge = 2 moles of electrons × 96500 Cmol Charge = 193000 C The quantity of charge needed to deposit 1 mole of copper is 193000 C. c) Observation: When crystals of iodine are heated gently, purple/violet vapor is observed. Explanation: Iodine undergoes sublimation, which is the direct change from a solid to a gaseous state without passing through a liquid phase. The iodine vapor has a characteristic purple color. 3 done, 2 left today. You're making progress.