Answer:
The correct balanced oxidation- reduction reaction is:
14H+(aq) + 6Fe2+(aq) + Cr2O72-(aq) -> 6Fe3+(aq) + 2Cr3+(aq) + 7H2O(l)
Step-by-step explanation:
In this reaction, iron (Fe2+) is the reducing agent while Cr2O7^2- is the oxidizing agent.
The ion transfer is represented as shown below:
6 Fe 2+ - 6e- -----------> 6 Fe 3+ (oxidation)
2 Cr^6 + 6e^- ----------> 2 Cr^3 (reduction)
From the unbalanced reaction
Fe2+ + Cr2O72- + H+ ----------> Fe3+ + Cr3+ + H2O we will follow these steps to balance the reaction.
Step 1: break the equation into two half reactions stating which is oxidized and reduced.
Step 2: Balance the atoms on each sides; the hydrogen, oxygen
Step 3: Balance the gain also
Step 4: Give the electron gained on one side to be equal to the electron lost on the other side.
Step 5: Add the two half reactions and simplify the equation.
Doing this, we obtain
14H+(aq) + 6Fe2+(aq) + Cr2O72-(aq) -> 6Fe3+(aq) + 2Cr3+(aq) + 7H2O(l)