Balance each of the following skeletal equations by using oxidation and reduction half reactions. All the reactions take place in acidic solution. Identify the oxidizing agent and reducing agent in each reaction. (Use the lowest possible coefficients. Include states-of-matter under SATP conditions in your answer.)

(a) Conversion of iron(II) into iron(III) by dichromate ion
Fe2+(aq) + Cr2O72-(aq) → Fe3+(aq) + Cr3+(aq)

For the equation, I put this and it returned:
"Your answer appears to be missing one or more states-of-matter."
6Fe^2+ + Cr_2O_7^2- + 14H^+ --> 6Fe^3+ + 2Cr^3+ + 7H_20

For the reducing reagent I put this and it returned: "Your answer appears to substitute one element for another."
Cr^6+

For the oxidizing reagent I put this and it returned: "Your answer differs too much from the expected answer to provide useful feedback."

Can someone help me correct what I did wrong?

2 answers

Sorry, for the oxidizing, I put this: Fe^2+
For the equation you didn't add any of the states; i.e., 6Fe^2+(aq) + Cr2O7^2-(aq) etc
Cr2O7^2-(aq) is the oxidizing agent; Fe^2+(aq) is the reducing agent.