Question

give the chemical formula,molar mass,and % compostionn of the following problems.round to the nearest 10
1)Calcium Hydroxide

Answer 1

1. **Chemical Formula:** Calcium Hydroxide is \( \text{Ca(OH)}_2 \).

2. **Molar Mass:**
- Calcium (Ca): 40.1 g/mol
- Oxygen (O): 16.0 g/mol (for 2 oxygen atoms: \( 2 \times 16.0 = 32.0 \) g/mol)
- Hydrogen (H): 1.0 g/mol (for 2 hydrogen atoms: \( 2 \times 1.0 = 2.0 \) g/mol)

Molar mass of \( \text{Ca(OH)}_2 \):
\[
40.1 \, \text{g/mol (Ca)} + 32.0 \, \text{g/mol (O)} + 2.0 \, \text{g/mol (H)} = 74.1 \, \text{g/mol}
\]

Rounding to the nearest ten: **70 g/mol**.

3. **% Composition:**
- % Composition of Calcium (Ca):
\[
\left( \frac{40.1}{74.1} \right) \times 100 \approx 54.1\% \approx 50\%
\]
- % Composition of Oxygen (O):
\[
\left( \frac{32.0}{74.1} \right) \times 100 \approx 43.2\% \approx 40\%
\]
- % Composition of Hydrogen (H):
\[
\left( \frac{2.0}{74.1} \right) \times 100 \approx 2.7\% \approx 0\%
\]

### Final Summary:
- Chemical Formula: \( \text{Ca(OH)}_2 \)
- Molar Mass: **70 g/mol**
- % Composition:
- Calcium (Ca): **50%**
- Oxygen (O): **40%**
- Hydrogen (H): **0%**