When manganese dioxide is added to hydrogen peroxide, oxygen and water are formed. Manganese dioxide acts as a catalyst to speed up the decomposition of hydrogen peroxide into oxygen and water.
The chemical formula of hydrogen peroxide is H2O2, the chemical formula for oxygen is O2, and the chemical formula for water is H2O. The balanced chemical equation for the decomposition of hydrogen peroxide is thus 2H2O2 ? O2 + 2H2O. When manganese dioxide is added to 2 moles of hydrogen peroxide, 1 mole of oxygen and 2 moles of water are formed. The manganese dioxide provides greater surface area for the decomposition to take place.