The decomposition reaction of hydrogen peroxide:
2 H₂O₂(aq) → 2 H₂O(l) + O₂(g)
The order of reaction is : first order reaction.
[H₂O₂]₀ = 12 M at time = 0
[H₂O₂] = 9.5 M at time = 30 minutes
Average reaction rate = - (Δ[reactants] / Δt)
= - (final reactants conc. - initial reactants conc.) / Δt
= - (9.5 M -12 M) / (30 min - 0 min)
= 0.083 mol / L.min