Write an equation for the oxidation of NH2OH to HNO3 by KBrO3. Balance the
reaction equation using the ion-electron method.
To write the equation for the oxidation of NH2OH to HNO3 by KBrO3 and balance it using the ion-electron method, follow these steps:
Step 1: Identify the elements and their oxidation states
Start by identifying the elements and their oxidation states in the reactants and products.
In the reactants:
- NH2OH: The oxidation state of N is -3, and the oxidation state of O is -2.
- KBrO3: The oxidation state of K is +1, the oxidation state of Br is +5, and the oxidation state of O is -2.
In the product:
- HNO3: The oxidation state of H is +1, the oxidation state of N is +5, and the oxidation state of O is -2.
Step 2: Write the unbalanced equation
Based on the information above, we can write the unbalanced equation:
NH2OH + KBrO3 → HNO3 + KBr + H2O
Step 3: Split the reaction into half-reactions
Separate the reaction into two half-reactions, one for the oxidation and one for the reduction.
Oxidation half-reaction:
NH2OH → HNO3
Reduction half-reaction:
KBrO3 → KBr
Step 4: Balance the atoms other than hydrogen and oxygen
Start by balancing the atoms other than hydrogen and oxygen in both half-reactions.
Oxidation half-reaction:
NH2OH → HNO3
The number of nitrogen atoms is already balanced.
Reduction half-reaction:
KBrO3 → KBr
The number of bromine atoms is already balanced.
Step 5: Balance the oxygen atoms
Next, balance the oxygen atoms by adding water molecules (H2O) to the side that needs additional oxygen.
Oxidation half-reaction:
NH2OH + H2O → HNO3 + H2O
Reduction half-reaction:
KBrO3 → KBr + O2
Step 6: Balance the hydrogen atoms
Balance the hydrogen atoms by adding hydrogen ions (H+) to the side that needs additional hydrogen.
Oxidation half-reaction:
NH2OH + H2O → HNO3 + 2H+ + 2e-
Reduction half-reaction:
KBrO3 → KBr + O2
Step 7: Balance the charges
Balance the charges in each half-reaction by adding electrons (e-) to the side that needs additional charge.
Oxidation half-reaction:
NH2OH + H2O → HNO3 + 2H+ + 2e-
Reduction half-reaction:
2BrO3- → Br2 + 3e-
Now the charges are balanced.
Step 8: Balance the number of electrons transferred
Make the overall number of electrons transferred equal in both half-reactions. Multiply each half-reaction by a suitable integer to balance the electrons.
Oxidation half-reaction:
2NH2OH + 2H2O → 2HNO3 + 4H+ + 4e-
Reduction half-reaction:
6BrO3- → 3Br2 + 9e-
Step 9: Combine the half-reactions
Multiply each half-reaction by numbers to make the number of electrons equal in both half-reactions. Then, combine the half-reactions.
2NH2OH + 2H2O + 6BrO3- → 2HNO3 + 4H+ + 4e- + 3Br2 + 9e-
Finally, simplify the equation and cancel out any common terms:
2NH2OH + 2H2O + 6BrO3- → 2HNO3 + 4H+ + 3Br2
This is the balanced equation for the oxidation of NH2OH to HNO3 by KBrO3 using the ion-electron method.