A current of 9.65 A is passed for 2000 s through a solution of a aluminium salt, where each Al ion gains 3 electrons. What mass of aluminium is deposited? (F = 96500 C/mol; molar mass 27 g/mol)
Answer and explanation
Correct answer: C. 1.8 g
- Step 1: Charge Q = It = 9.65 × 2000 = 19300 C, which is 0.2 mol of electrons. Step 2. Moles of metal = 0.2 ÷ 3, so mass = 1.8 g. Answer: 1.8 g. Why not the others: 5.4 g is what you get if you forget to divide by the electrons per ion. 0.6 g is what you get if you divide by the electrons twice. 18 g is what you get if you misplace a power of ten.
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