Balance each redox reaction using the half-reaction method.
(a) Zn(s) + Sn2+ (aq) → Zn2+ (aq) + Sn(s)
(b) Mg(s) + Cr3+ (aq) → Mg2+ (aq) + Cr(s)
(c) Al(s) + Ag+ (aq) → Al3+ (aq) + Ag(s)
Problem 62P :
Here, we have to balance each redox reaction using the half-reaction method :
Half reaction is either the oxidation or the reduction reaction of a redox reaction.
Steps to balance redox reaction using the half reaction method :
- First, we assign oxidation states to all atoms and then identify the substances that are being oxidized and reduced.
- Then we separate the overall reaction into two half-reactions - oxidation and reduction.
- Next, we balance each half-reaction with respect to mass in the following order :
- Balance all elements other than H and O.
- Balance O by adding H2O.
- Balance H by adding H+.
- Next, we balance each half-reaction with respect to charge by adding electrons to the right side of the oxidation half-reaction and the left side of the reduction half-reaction, making the sum of the charges on both sides of each equation equal.
- Next, we equal the number of electrons in both half-reactions by multiplying one or both half-reactions by a small whole number.
- Then we add the two half-reactions together, canceling electrons and other species as necessary.
- Finally we verify that the reaction is balanced with respect to both mass and charge.