First, vitamin C (C₆H₈O₆) reacts with molecular iodine (I₂, dark brown color) to produce the iodide ion (I⁻, colorless):

C₆H₈O₆ (aq) + I₂ (aq) → 2 H⁺ (aq) + 2 I⁻ (aq) + C₆H₆O₆ (aq)           (Reaction 1)

When hydrogen peroxide is added, the iodide ion is oxidized back to molecular iodine:

2 I⁻ (aq) + 2 H⁺ (aq) + H₂O₂ (aq) → I₂ (aq) + 2 H₂O (l)           (Reaction 2)

Use the dilution equation (M₁V₁ = M₂V₂)  to calculate the concentrations of each reagent in the reaction mixture immediately after the solutions in Beaker 1 and Beaker 2 are mixed (the total volume is 30 mL for all experiments). These are the “initial concentrations” for the reaction, [C₆H₈O₆]₀ , [I⁻]₀ , and [H₂O₂]₀ .