Balancing Redox Reactions

Balancing using oxidation number

Balancing using half reaction

Steps

1-The first step in balancing any redox reaction is determining oxidation-reduction reaction.

2-divide the oxidation and reduction equations in half

3-Balance elements in the equation other than O and H.

5- Balance the oxygen atoms by adding the appropriate number of water (H2O) molecules to the opposite side of the equation.

6- Balance the hydrogen atoms (including those added in step 2 to balance the oxygen atom) by adding H+ ions to the opposite side of the equation.

7- Add up the charges on each side. Make them equal by adding enough electrons (e-) to the more positive side. (Rule of thumb: e- and H+ are almost always on the same side.)

If basic solution

8-If the equation is being balanced in a basic solution, through the addition of one more step, the appropriate number of OH- must be added to turn the remaining H+ into water molecules.

Example

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  1. Write an unbalanced equation
  1. Separate the process into half reactions

a) Assign oxidation numbers for each atom

b) Identify and write out all redox couples in reaction

c) Combine these redox couples into two half-reactions

  1. Make electron gain equivalent to electron loss in the half-reactions

4.Add the half-reactions together

  1. check if the chemical reaction is balance or not

Example

Oxidation_number_method

Prepared by: Ghalia Altukhaifi

Redox Reaction

Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion.


Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.