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 + 10HNO3 --> 2HIO3 + 10NO2 + H2O
i cant balance now.
To balance the given chemical equation using the oxidation number method, follow these steps:
1. Assign oxidation numbers to all elements in the equation. Remember that the sum of the oxidation numbers in a compound must be equal to its overall charge, and for elements by themselves, the oxidation number is always zero.
2. Identify the elements whose oxidation numbers are changing. These elements are undergoing oxidation or reduction.
In the given equation, we observe that the oxidation number of iodine (I) is changing from 0 to +5 and nitrogen (N) is changing from +5 to +4. Therefore, these are the elements we need to focus on.
3. Determine the change in oxidation number for the changing elements and balance the equation by adding coefficients.
For iodine (I), the oxidation number is increasing from 0 to +5, which is a change of +5. To balance this, we need to add a coefficient of 2 in front of HIO3.
For nitrogen (N), the oxidation number is decreasing from +5 to +4, which is a change of -1. To balance this, we need to add a coefficient of 10 in front of NO2.
After adding these coefficients, the balanced equation becomes:
I2 + 10HNO3 --> 2HIO3 + 10NO2 + H2O
4. Verify that the equation is balanced by checking the elements and the charges on both sides. In this case, the number of atoms of each element and the overall charges are balanced.
Note: The oxidation number method is one of several methods used to balance chemical equations. It involves tracking the change in oxidation numbers of specific elements. Other methods, such as the half-reaction method or the ion-electron method, can also be used to balance redox reactions.