Calculate the percent by mass of water in magnesium sulfate heptahydrdrate (MgSO4-7H2O)
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To calculate the percent by mass of water in magnesium sulfate heptahydrate (MgSO4·7H2O), you need to determine the total mass of water and divide it by the total mass of the compound.
Here's how you can do it step-by-step:
1. Determine the molar mass of magnesium sulfate heptahydrate (MgSO4·7H2O).
- The molar mass of magnesium (Mg) is 24.31 grams per mole.
- The molar mass of sulfur (S) is 32.07 grams per mole.
- The molar mass of oxygen (O) is 16.00 grams per mole.
- The molar mass of hydrogen (H) is 1.01 grams per mole.
- Multiply the molar mass of each element by the number of atoms in the compound and sum them up to find the molar mass of MgSO4·7H2O.
Molar mass of MgSO4·7H2O = (24.31 g/mol) + (32.07 g/mol) + (4 × 16.00 g/mol) + (7 × (2 × 1.01 g/mol))
= 120.37 g/mol
2. Determine the mass of water in magnesium sulfate heptahydrate.
- The molar mass of water (H2O) is 18.02 grams per mole.
- Multiply the molar mass of water by the number of water molecules (7) in MgSO4·7H2O.
Mass of water = (18.02 g/mol) × (7 mol)
= 126.14 g
3. Determine the total mass of magnesium sulfate heptahydrate.
- This can be done by adding the molar mass of MgSO4 and the mass of water.
Total mass of MgSO4·7H2O = (Molar mass of MgSO4) + (Mass of water)
= (120.37 g/mol) + (126.14 g)
= 246.51 g
4. Calculate the percent by mass of water.
- Divide the mass of water by the total mass of the compound and multiply by 100 to get the percentage.
Percent by mass of water = (Mass of water / Total mass of MgSO4·7H2O) × 100
= (126.14 g / 246.51 g) × 100
≈ 51.17%
Therefore, the percent by mass of water in magnesium sulfate heptahydrate (MgSO4·7H2O) is approximately 51.17%.