Percentage Composition
Percentage composition refers to the percentage by mass of each element present in a compound. It is determined using the formula:
Percentage composition of element (X) = (Mass of X / Total mass of compound) × 100%
Example:
Determine the percentage composition of Carbon (C), Hydrogen (H), and Oxygen (O) in glucose (C6H12O6).
Step 1: Calculate the molar mass of glucose.
Molar mass of C6H12O6 = (6 × 12 g/mol) + (12 × 1 g/mol) + (6 × 16 g/mol)
= 72 g + 12 g + 96 g
= 180 g/mol
Step 2: Calculate the percentage composition of each element:
Percentage of Carbon (C) = (72 g / 180 g) × 100% = 40%
Percentage of Hydrogen (H) = (12 g / 180 g) × 100% = 6.67%
Percentage of Oxygen (O) = (96 g / 180 g) × 100% = 53.33%
Illustrative Table:
| Element | Molar Mass Contribution | Percentage Composition |
|---|---|---|
| Carbon (C) | 72 g | 40% |
| Hydrogen (H) | 12 g | 6.67% |
| Oxygen (O) | 96 g | 53.33% |
