How many grams of hydrogen peroxide (H2O2) must be added to 1,500 ml of water to produce a concentration of 1.33 m (molal solution)?
To determine the number of grams of hydrogen peroxide (H2O2) needed to prepare a 1.33 m (molal) solution, you need to know the molecular weight of H2O2 and the volume of the solution.
1. Find the molecular weight of H2O2:
- Atomic weight of hydrogen (H) = 1 grams/mole
- Atomic weight of oxygen (O) = 16 grams/mole
- H2O2 = 2(H) + 2(O) = 2(1) + 2(16) = 34 grams/mole
2. Calculate the number of moles of H2O2 needed:
- 1.33 m concentration means 1.33 moles of H2O2 per kilogram of water
- To find the number of moles for 1,500 ml of water (1.5 liters), convert the volume to kilograms:
- 1 liter of water = 1 kilogram
- 1,500 ml of water = 1.5 liters = 1.5 kg
- Therefore, you need 1.33 moles of H2O2 per 1.5 kg of water
3. Calculate the mass of H2O2 needed in grams:
- Mass = moles × molecular weight
- Mass of H2O2 = 1.33 moles × 34 grams/mole = 45.22 grams
Therefore, you would need approximately 45.22 grams of hydrogen peroxide (H2O2) to make a 1.33 m (molal) solution in 1,500 ml of water.
m = mols/kg solvent
1.33 = mols/1.5
mols = ?
Then grams = mols x molar mass.