Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass.
What is the molarity of this solution? (Assume a density of 1.01 g/mL.)
To determine the molarity of the solution, we need to use the formula:
Molarity (M) = moles of solute / volume of solution in liters
First, we need to calculate the mass of hydrogen peroxide in the solution. Since the solution contains 3.0% hydrogen peroxide by mass, we can assume that there are 3.0 grams of hydrogen peroxide in 100 grams of the solution.
If we want to find the moles, we need to know the molar mass of hydrogen peroxide. The molar mass of hydrogen peroxide (H2O2) is approximately 34.0147 g/mol.
Moles of solute = mass of solute / molar mass
Moles of solute = 3.0 g / 34.0147 g/mol
Now, let's calculate the volume of the solution. We know that density = mass / volume, so we can rearrange the formula to solve for volume:
Volume of solution = mass of solution / density
Volume of solution = 100 g / 1.01 g/mL
Since the molarity is defined as moles of solute per liter of solution, we need to convert the volume of the solution from milliliters to liters:
Volume of solution (in L) = Volume of solution (in mL) / 1000
Now that we have all the values, we can calculate the molarity:
Molarity (M) = moles of solute / volume of solution (in L)
Substituting the values we calculated earlier:
Molarity (M) = (3.0 g / 34.0147 g/mol) / (100 g / 1.01 g/mL / 1000)
Now, let's simplify the expression:
Molarity (M) = (3.0 g / 34.0147 g/mol) / (0.1001 L)
Finally, calculate the molarity:
Molarity (M) ≈ 0.089 M
Therefore, the molarity of the household hydrogen peroxide solution is approximately 0.089 M.