College

The percentage by mass of calcium in [tex]CaCl_2[/tex] is:

Given:

[tex]Ca = 40.0[/tex], [tex]Cl = 35.5[/tex], [tex]O = 16.0[/tex]

Answer :

To find the percentage by mass of calcium in [tex]\( \text{Ca(ClO}_3)_2 \)[/tex], we will follow these steps:

1. Identify the atomic masses:
- Calcium (Ca): 40.0 g/mol
- Chlorine (Cl): 35.5 g/mol
- Oxygen (O): 16.0 g/mol

2. Understand the molecular formula:
- The compound is [tex]\( \text{Ca(ClO}_3)_2 \)[/tex].
- This means it contains one calcium atom, two chlorine atoms, and six oxygen atoms (as each [tex]\(\text{ClO}_3\)[/tex] group contains three oxygens).

3. Calculate the molar mass of [tex]\( \text{Ca(ClO}_3)_2 \)[/tex]:
- Calcium: [tex]\( 1 \times 40.0 = 40.0 \)[/tex] g/mol
- Chlorine: [tex]\( 2 \times 35.5 = 71.0 \)[/tex] g/mol
- Oxygen: [tex]\( 6 \times 16.0 = 96.0 \)[/tex] g/mol

Add these together to get the total molar mass of the compound:

[tex]\[
\text{Molar mass of } \text{Ca(ClO}_3)_2 = 40.0 + 71.0 + 96.0 = 207.0 \text{ g/mol}
\][/tex]

4. Calculate the percentage by mass of calcium:
- The percentage by mass is calculated by dividing the mass of calcium by the molar mass of the compound and then multiplying by 100:

[tex]\[
\text{Percentage of Ca} = \left( \frac{40.0}{207.0} \right) \times 100 \approx 19.32\%
\][/tex]

Therefore, the percentage by mass of calcium in [tex]\( \text{Ca(ClO}_3)_2 \)[/tex] is approximately 19.32%.