How do you prepare 300 micro molar H2O2 using 3.0 percent H2O2?

Answer 1

Too many unknowns in your question. Is this 3% by mass or by volume? Does the quantity of final solution matter? IE do you need 100 ml, 1 liter or 5000ml. What is the density of the hydrogen peroxide? (needed for a volume % problem)

Assuming you mean 3% by mass, then that means 3 g of hydrogen peroxide in 100 g of solution. 300 micromolar = 3 x 10-4 molar. Assuming you want to make one liter then you need 3 x 10-4 moles of peroxide. The molar mass of peroxide is 34 g/mole.

34 g/mole x 3 x 10-4 moles = 1.02 x 10-2 grams of peroxide

1.02 x 10-2 grams / .03 = 0.34 grams of the original solution.

Weigh (mass) accurately 0.34 g of the original solution in a 1 liter volumetric flask. Add distilled water until the total volume is 1 liter.

Answer 2

To prepare a 300 µM solution of H2O2 from a 3.0% H2O2 stock solution:

1. Calculate the molarity of the 3.0% solution by dividing the percentage by the molar mass of H2O2.
2. Then, use the formula C1V1 = C2V2, where C1 is the molarity of the stock solution, V1 is the volume needed to prepare, C2 is the desired molarity (300 µM), and V2 is the final volume of the solution (usually in mL).

After solving for V1 (volume needed to prepare), measure this volume from the stock solution and dilute it to the final volume with the appropriate solvent (usually water).