Calculate the molarity of (mol/L) of 3% hydrogen peroxide and record it in Data Table 2. The term “3% concentration” is a weight-to-weight measurement, which means that there are 3 g solute per 100 g solvent. The molar mass of hydrogen peroxide is 34.01 g/mol and the density of the solution is 1.01 g/mL.
The Correct Answer and Explanation is :
The molarity of a 3% hydrogen peroxide solution is approximately 0.891 mol/L.
Explanation:
To calculate the molarity (mol/L) of a 3% hydrogen peroxide solution, we follow these steps:
- Mass of Solution:
The 3% concentration means that there are 3 grams of hydrogen peroxide (H₂O₂) per 100 grams of solution. For simplicity, we assume a 1-liter solution (1000 mL). Given that the density of the solution is 1.01 g/mL, the mass of the entire solution in 1 liter is calculated as: [
\text{Mass of solution} = \text{density} \times \text{volume} = 1.01 \, \text{g/mL} \times 1000 \, \text{mL} = 1010 \, \text{grams}
] - Mass of Hydrogen Peroxide:
Since the solution is 3% H₂O₂ by weight, the mass of hydrogen peroxide in the 1-liter solution is: [
\text{Mass of H₂O₂} = \frac{3}{100} \times 1010 \, \text{g} = 30.3 \, \text{g}
] - Moles of Hydrogen Peroxide:
To calculate the number of moles of H₂O₂, we use its molar mass, which is 34.01 g/mol. Thus, the number of moles of H₂O₂ in the solution is: [
\text{Moles of H₂O₂} = \frac{30.3 \, \text{g}}{34.01 \, \text{g/mol}} \approx 0.891 \, \text{mol}
] - Molarity of Hydrogen Peroxide:
Molarity is defined as moles of solute per liter of solution. Therefore, for a 1-liter solution: [
\text{Molarity} = \frac{0.891 \, \text{mol}}{1 \, \text{L}} = 0.891 \, \text{mol/L}
]
This gives us the molarity of the hydrogen peroxide solution as approximately 0.891 mol/L.