Lesson 7: Activity 1
Calculate the formula mass and percentage composition of the following compounds
1. NaOH
2. CaCl2 · 6H20                                                                                                                                           
3. Glucose (C6H12O6)

### To calculate the **formula mass** and **percentage composition** of each compound, we need the atomic masses of the elements involved. We'll use the following approximate atomic masses (in g/mol):

- Na = 22.99
- O = 16.00
- H = 1.01
- Ca = 40.08
- Cl = 35.45
- C = 12.01
- H (for glucose) = 1.01
- O (for glucose) = 16.00

### 1. **Sodium hydroxide (NaOH)**

**Formula mass:**
\[
\text{NaOH} = (\text{Na}) + (\text{O}) + (\text{H}) = 22.99 + 16.00 + 1.01 = 40.00 \, \text{g/mol}
\]

**Percentage composition:**

- **Sodium (Na):** 
\[
\left( \frac{22.99}{40.00} \right) \times 100 = 57.48\%
\]
- **Oxygen (O):**
\[
\left( \frac{16.00}{40.00} \right) \times 100 = 40.00\%
\]
- **Hydrogen (H):**
\[
\left( \frac{1.01}{40.00} \right) \times 100 = 2.53\%
\]

### 2. **Calcium chloride hexahydrate (CaCl₂ · 6H₂O)**

**Formula mass:**
\[
\text{CaCl}_2 \cdot 6\text{H}_2\text{O} = \text{Ca} + 2(\text{Cl}) + 6(\text{H}_2\text{O})
\]
Breaking it down:
- Calcium (Ca) = 40.08
- 2 Chlorine (Cl) atoms = 2 × 35.45 = 70.90
- 6 Water molecules = 6 × (2 × 1.01 + 16.00) = 6 × 18.02 = 108.12

Total formula mass:
\[
40.08 + 70.90 + 108.12 = 219.10 \, \text{g/mol}
\]

**Percentage composition:**

- **Calcium (Ca):**
\[
\left( \frac{40.08}{219.10} \right) \times 100 = 18.29\%
\]
- **Chlorine (Cl):**
\[
\left( \frac{70.90}{219.10} \right) \times 100 = 32.37\%
\]
- **Water (H₂O):**
\[
\left( \frac{108.12}{219.10} \right) \times 100 = 49.34\%
\]

### 3. **Glucose (C₆H₁₂O₆)**

**Formula mass:**
\[
\text{C}_6\text{H}_{12}\text{O}_6 = 6(\text{C}) + 12(\text{H}) + 6(\text{O})
\]
Breaking it down:
- 6 Carbon (C) atoms = 6 × 12.01 = 72.06
- 12 Hydrogen (H) atoms = 12 × 1.01 = 12.12
- 6 Oxygen (O) atoms = 6 × 16.00 = 96.00

Total formula mass:
\[
72.06 + 12.12 + 96.00 = 180.18 \, \text{g/mol}
\]

**Percentage composition:**

- **Carbon (C):**
\[
\left( \frac{72.06}{180.18} \right) \times 100 = 39.99\%
\]
- **Hydrogen (H):**
\[
\left( \frac{12.12}{180.18} \right) \times 100 = 6.73\%
\]
- **Oxygen (O):**
\[
\left( \frac{96.00}{180.18} \right) \times 100 = 53.28\%
\]

---

Would you like more details on any of these calculations or further clarifications?

### Related Questions:
1. How would the formula mass of NaOH change if it contained more oxygen atoms?
2. What is the role of water in the formula mass of hydrated compounds like CaCl₂ · 6H₂O?
3. Why does glucose have a higher percentage of oxygen compared to other elements?
4. How does the molecular structure of glucose impact its chemical properties?
5. How do you calculate the formula mass of complex organic compounds?

### Tip: 
For hydrated compounds like CaCl₂ · 6H₂O, don't forget to account for the water molecules in both formula mass and percentage composition calculations.

Lesson 7: Activity 1
Calculate the formula mass and percentage composition of the following compounds
1. NaOH
2. CaCl2 · 6H2O
3. Glucose (C6H12O6)

Learn how to calculate the formula mass and percentage composition of NaOH, CaCl2 · 6H2O, and glucose (C6H12O6). This step-by-step guide covers essential concepts in stoichiometry and molecular mass calculations, suitable for students in Grades 9-12.

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