What is the molar mass of calcium nitrate? (a) 150.08 g/mol (b) 102.08 g/mol (c) 164.09 g/mol (d) 68.09 g/mol
The Correct Answer and Explanation is:
The molar mass of calcium nitrate (Ca(NO₃)₂) can be calculated by adding up the atomic masses of all the elements in the formula. To break it down:
- Calcium (Ca): The atomic mass of calcium is approximately 40.08 g/mol. Since there is 1 calcium atom in the formula, it contributes 40.08 g/mol.
- Nitrogen (N): The atomic mass of nitrogen is approximately 14.01 g/mol. There are 2 nitrogen atoms in the formula (from the two NO₃ groups), so the contribution from nitrogen is 2 × 14.01 g/mol = 28.02 g/mol.
- Oxygen (O): The atomic mass of oxygen is approximately 16.00 g/mol. There are 6 oxygen atoms in the formula (since each nitrate group, NO₃, contains 3 oxygen atoms, and there are two NO₃ groups). The contribution from oxygen is 6 × 16.00 g/mol = 96.00 g/mol.
Now, we can add these values together to find the molar mass:40.08 g/mol (Ca)+28.02 g/mol (N)+96.00 g/mol (O)=164.10 g/mol40.08 \, \text{g/mol (Ca)} + 28.02 \, \text{g/mol (N)} + 96.00 \, \text{g/mol (O)} = 164.10 \, \text{g/mol}40.08g/mol (Ca)+28.02g/mol (N)+96.00g/mol (O)=164.10g/mol
Therefore, the correct answer is (c) 164.09 g/mol, which is the molar mass of calcium nitrate.
This mass represents the amount of calcium nitrate in one mole of the compound. The molar mass is essential for converting between grams and moles in chemical reactions.
