Question

aluminum plating is sometimes used to reduce corrosion in materials exposed to the outdoors. a section of a metal roof is plated with aluminum for a builder. a current is applied to an aluminum sulfate solution. how many moles of electrons are transferred during the reduction of aluminum? ? mole e⁻

Explanation:

Step1: Determine the reduction half - reaction of aluminum

The aluminum ion in aluminum sulfate ($\ce{Al2(SO4)3}$) has a charge of +3, so the aluminum ion is $\ce{Al^{3+}}$. The reduction half - reaction for aluminum is $\ce{Al^{3+} + 3e^-
ightarrow Al}$.

Step2: Analyze the moles of electrons transferred per mole of Al reduction

From the reduction half - reaction $\ce{Al^{3+} + 3e^-
ightarrow Al}$, for every 1 mole of $\ce{Al^{3+}}$ that is reduced to 1 mole of $\ce{Al}$, 3 moles of electrons are transferred. When we consider the reduction of aluminum (from $\ce{Al^{3+}}$ to $\ce{Al}$), the number of moles of electrons transferred per mole of aluminum formed (or per mole of $\ce{Al^{3+}}$ reduced) is 3. Since the question is about the reduction of aluminum (implied per mole of aluminum), the number of moles of electrons transferred is 3.

Answer:

3