Question looking for the reduction half reaction?

Question

Given the following net ionic equation:

 3 Zn_(s) + 2 Fe³⁺_(aq) →  3 Zn²⁺_(aq) + 2 Fe_(s)

The reaction that represent the reduction half-reaction is:

Question 1 options:

a.	Zn2+(aq) + 2e−→Zn(s)
b.	Fe3+(aq) + 3 e−→ Fe(s)
c.	Fe(s) → Fe3+(aq) + 3 e−
d.	Zn(s) →Zn2+(aq) + 2e−

Answer 1

Answer: b

Explanation: Determine the oxidation states of each reactant and each product. For pure elements, the oxidation states are zero. For ions, the oxidation states are the charges. In polyatomic molecules, the oxidation states of each atom sum to the charge of the molecule. Half reactions show the movement of electrons. Reduction corresponds to the reduction of the oxidation state of an atom through the gain of electrons. Answer choice b clearly shows Ferric cation gaining 3 electrons to form solid Fe. The oxidation state of the cation is +3, and the oxidation state of solid Fe is 0, hence a reduction in oxidation state. And by reduction we mean along the number line from a larger number to a smaller number. Please feel free to post a follow-up question, if you like.