Question

Explain how to balance chemical equations by oxidation-reduction method.

Answer 1

1. Write the skeleton redox reaction.
2. Indicate the oxidation number of atoms in each compound above the symbol of the element.
3. Identify the element or elements, which undergo a change in oxidation number, one whose oxidation number increases (reducing agent) and the other whose oxidation number decreases (oxidizing agent).
4. Calculate the increase or decrease in oxidation number per atom. Multiply this number of increase/decrease of oxidation number, with the number of atoms, which are undergoing change.
5. Equate the increase in oxidation number with a decrease in oxidation number on the reactant side by multiplying the formula of the oxidizing and reducing agents.
6. Balance the equation with respect to all other atoms except hydrogen and oxygen.
7. Finally, balance hydrogen and oxygen.
8. For reactions taking place in acidic solutions, add $H^{+}$ ions to the side deficient in hydrogen atoms.
9. For reactions taking place in basic solutions, add $H_{2}O$ molecules to the side deficient in hydrogen atoms and simultaneously add equal number to $O{H}^{-}$ ions on the other side of the equation.