Laboratory Preparation of Oxygen
Oxygen can be prepared in a number of ways in the laboratory. These include:
(a). Heating a mixture of potassium trioxochlorate(V), KClO3 and maganese(IV) oxide, MnO2.
The MnO2 acts as a catalyst. The reaction is actually the decomposition of KClO3.
2KClO3(s) → 2KCl(s) + 3O2(g)
(b). The decomposition of hydrogen peroxide, H2O2 using manganese(IV) oxide - this does not require heating.
Hydrogen peroxide is added drop wisely unto MnO2.
2H2O2(aq) → 2H2O(l) + O2(g)
Or by the drop wise addition of hydrogen peroxide on acidified KMnO4
5H2O2(aq) + 2KMnO4(aq) + 3H2SO4(aq) → K2SO4(aq) + 2MnSO4(aq) + 8H2O(l) + 5O2(g)
(c). The reaction between water and sodium peroxide.
Hydrogen peroxide is formed, and it immediately decomposes by the catalytic effect of the OH- ions in solution.
Na2O2(s) + 2H2O → H2O2 + 2Na+ + 2OH-
Then, 2H2O2 → 2H2O + O2
(d). Application of heat on trioxonitrate(V) salts of metals.
Trioxonitrate(V) salts of metals, e.g, sodium trioxonitrate(V), NaNO3 give off a part of their oxygen upon being heated. NaNO3 loses one third of its oxygen.
2NaNO3(s) → 2NaNO2(s) + O2(g)