What is the mass percent of water in magnesium chloride hexahydrate? Provide an answer to two decimal
The Correct Answer and Explanation is:
To calculate the mass percent of water in magnesium chloride hexahydrate (MgCl2·6H2O), we need to first find the molar mass of the compound and the molar mass of the water molecules within it.
Step 1: Calculate the Molar Mass of MgCl2·6H2O
- Magnesium chloride (MgCl2):
- Magnesium (Mg): 24.31 g/mol
- Chlorine (Cl): 2 × 35.45 g/mol = 70.90 g/mol
- Total for MgCl2 = 24.31 + 70.90 = 95.21 g/mol
- Water (H2O):
- Hydrogen (H): 2 × 1.008 g/mol = 2.016 g/mol
- Oxygen (O): 16.00 g/mol
- Total for H2O = 2.016 + 16.00 = 18.016 g/mol
- Since there are 6 water molecules in the formula, the total mass of water is:
6 × 18.016 g/mol = 108.096 g/mol - Molar mass of MgCl2·6H2O = Molar mass of MgCl2 + Mass of 6 H2O molecules
= 95.21 g/mol + 108.096 g/mol = 203.306 g/mol
Step 2: Calculate the Mass Percent of Water
- Mass of water in the hydrate = 108.096 g/mol
- Molar mass of MgCl2·6H2O = 203.306 g/mol
- Mass percent of water = (Mass of water / Molar mass of MgCl2·6H2O) × 100
= (108.096 / 203.306) × 100 = 53.18%
Conclusion:
The mass percent of water in magnesium chloride hexahydrate (MgCl2·6H2O) is 53.18%.
This calculation involves adding up the masses of each element in the formula and finding their respective proportions. Since the mass of water is more than half the total mass of the compound, we see that water is a significant component of the hydrate.
