The hydrogen peroxide solution that you are using in this experiment is labeled

Question

The hydrogen peroxide solution that you are using in this experiment is labeled as a 3.0% solution, mass/volume (i.e. 3.0 g of H_2 O_2 in 100. mL of solution). However, in order to complete the calculations, the concentration must be in molarity. Calculate the molarity of a 3% mass/volume H_2 O_2 solution and record the answer in the appropriate cell(s) in Table 1. Reagent Solution Concentrations prior to Mixing (MM H_2 O_2: 34.01 g/mole). Units: M. The KI solution will be prepared by the stockroom by dissolving 41.5 g of potassium iodide in water, with a total solution volume of 500. mL. Record the answer in the appropriate cell (s) in Table 1. Reagent Solution Concentrations prior to Mixing (MM K1: 166.0 g/mole). Units: M.

Explanation / Answer

1. molarity of H2O2 solution

moles of H2O2 = 3g/34.01 g/mol = 0.09 mols

molarity of H2O2 solution = 0.09 mol/0.1 L = 0.88 M

2. moles of KI = 41.5 g/166 g/mol = 0.25 mols

molarity of KI solution = 0.25 mol/0.5 L = 0.5 M

3. Reagent table

Trial      [H2O2] (M)          [KI] (M)

           before mixing    before mixing

I               0.0058               0.00083

II              0.0058               0.00083

III             0.0058               0.00083

etc.          0.0058               0.00083

[H2O2] (M) before mixing = 0.88 M x 4 ml/600 ml = 0.0058 M

[KI] (M) before mixing = 0.5 M x 1 ml/600 ml = 0.00083 M

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