To calculate the percentage by mass of water of crystallization in MgSO4.7H2O, we need to find the molar mass of MgSO4.7H2O and the molar mass of the 7 moles of H2O in the compound, and then compare the mass of the water to the mass of the entire compound.
First, let's find the molar mass of MgSO4:
Mg = 24.3 g/mol
S = 32.1 g/mol
O = 16.0 g/mol (We have 4 oxygen atoms in SO4, so we will multiply by 4)
Molar mass of MgSO4 = 24.3 g/mol (Mg) + 32.1 g/mol (S) + (4 x 16.0 g/mol (O))
Molar mass of MgSO4 = 24.3 + 32.1 + 64.0
Molar mass of MgSO4 = 120.4 g/mol
Next, let's find the molar mass of 7 moles of H2O in the compound:
H = 1.0 g/mol (We have 2 hydrogen atoms in H2O, so we will multiply by 2)
O = 16.0 g/mol
Molar mass of H2O = (2 x 1.0 g/mol (H)) + 16.0 g/mol (O)
Molar mass of H2O = 2.0 + 16.0
Molar mass of H2O = 18.0 g/mol
Now, we have 7 moles of H2O in the compound, so the mass of water is:
Mass of 7 moles of water = 7 x 18.0 g/mol
Mass of 7 moles of water = 126.0 g/mol
To find the molar mass of MgSO4.7H2O, we will add the molar mass of MgSO4 and the mass of 7 moles of water:
Molar mass of MgSO4.7H2O = 120.4 g/mol (MgSO4) + 126.0 g/mol (7H2O)
Molar mass of MgSO4.7H2O = 246.4 g/mol
Now, we will calculate the percentage by mass of water in MgSO4.7H2O:
Percentage by mass of water = (Mass of 7 moles of water) / (Molar mass of MgSO4.7H2O) x 100
Percentage by mass of water = (126.0 g/mol) / (246.4 g/mol) x 100
Percentage by mass of water ≈ 51.14 %
So, the percentage by mass of water of crystallization in MgSO4.7H2O is approximately 51.14%.
Calculate the percentage by mass of water of crystallization in MgSO4.7H2O
1 answer