Calculate the molar mass of CaCl2 2H2O
The correct answer and explanation is:
To calculate the molar mass of calcium chloride dihydrate (CaCl2·2H2O), you need to add the molar masses of each component in the compound.
Step-by-Step Calculation:
- Calcium (Ca):
The molar mass of calcium (Ca) is approximately 40.08 g/mol. - Chlorine (Cl):
There are two chlorine atoms in calcium chloride, and each chlorine atom has a molar mass of approximately 35.45 g/mol.
Therefore, the total molar mass of chlorine in CaCl2 is: 2×35.45 g/mol=70.90 g/mol2 \times 35.45 \, \text{g/mol} = 70.90 \, \text{g/mol} - Water (H2O):
Each water molecule (H2O) has a molar mass of approximately 18.015 g/mol. Since there are two water molecules in the formula (CaCl2·2H2O), the total molar mass of water is: 2×18.015 g/mol=36.030 g/mol2 \times 18.015 \, \text{g/mol} = 36.030 \, \text{g/mol}
Total Molar Mass Calculation:
Now, sum the molar masses of all the components: Molar mass of CaCl2\cdotp2H2O=Molar mass of Ca+Molar mass of Cl2+Molar mass of 2H2O\text{Molar mass of CaCl2·2H2O} = \text{Molar mass of Ca} + \text{Molar mass of Cl2} + \text{Molar mass of 2H2O} Molar mass of CaCl2\cdotp2H2O=40.08 g/mol+70.90 g/mol+36.030 g/mol\text{Molar mass of CaCl2·2H2O} = 40.08 \, \text{g/mol} + 70.90 \, \text{g/mol} + 36.030 \, \text{g/mol} Molar mass of CaCl2\cdotp2H2O=146.00 g/mol\text{Molar mass of CaCl2·2H2O} = 146.00 \, \text{g/mol}
Explanation:
Molar mass is the mass of one mole of a substance, and it is calculated by summing the masses of all the atoms in the compound. In this case, we break down the molar mass of calcium chloride dihydrate into its components: calcium (Ca), chlorine (Cl), and water (H2O). The presence of water molecules in the compound is important as it adds additional mass to the total molar mass. Calcium chloride dihydrate is commonly used in desiccants, and knowing its molar mass is essential for accurate calculations in stoichiometry, such as when preparing solutions or performing chemical reactions involving this substance.