6 KMnO4 (aq) + 9 H2SO4 (aq) → 5 O3 (g) + 6 MnSO4 (aq) + 3 K2SO4 (aq) + 9 H2O (l)
This is an oxidation-reduction (redox) reaction:
6 MnVII + 30 e- → 6 MnII (reduction)
15 O-II - 30 e- → 15 O0 (oxidation)
This is a gas evolution reaction, O3 is the formed gas.