Question

Question: Balance the following reactions by the oxidation number method.

a) I2 + HNO3 --> HIO3 + NO2 + H2O

so i have
N +5 to +4 net charge = -1
I 0 to +5 net charge = +5

i add coefficient where the oxidation number is changing.

in this case
I2 + 4HNO3 --> 2HIO3 + 4NO2 + H2O

i cant balance now.

Answer 1

it takes five I for every one N
So if you are using I2, you will change 10N

I2+10HNO3>> HIO3 + NO2 + H2O

start then with 2 in front of HIO3, 10 NO2, and .....

Answer 2

Read over my earlier post to you. I mentioned that most beginning students made a mistake in not using the same number of atoms; therefore, "you should add a 2 in front of the HIO3." That way the I2 goes from a total of zero on the left to 2HIO3 or 10 total on the right.