1. What is Percent Composition?

Percent composition is the percentage by mass of each element in a compound. For water (H₂O), it represents the mass percentage of hydrogen and oxygen in the molecule.

2. How Does the Calculator Work?

The calculator uses the percent composition formula:

Where:

• \( \text{Number of H atoms} \) — Hydrogen atoms in the molecule (2 for water)
• \( \text{Atomic mass of H} \) — 1.008 g/mol (simplified to 1 in basic calculations)
• \( \text{Molar mass of compound} \) — Total molecular weight (18 g/mol for water)

Explanation: The formula calculates what portion of the total molecular weight comes from hydrogen.

3. Importance of Percent Composition

Details: Percent composition is essential for determining empirical formulas, understanding chemical reactions, and analyzing purity of compounds.

4. Using the Calculator

Tips: Enter the number of hydrogen atoms and the molar mass of the compound. For water, use 2 hydrogen atoms and 18 g/mol molar mass.

5. Frequently Asked Questions (FAQ)

Q1: What is the percent composition of hydrogen in water?
A: Approximately 11.11% (2/18 × 100).

Q2: How do I calculate percent composition for other elements?
A: Use the same formula but substitute the element's atomic mass and count in the molecule.

Q3: Why is the atomic mass of hydrogen considered 1?
A: For simplicity in basic calculations, though the actual atomic mass is 1.008 g/mol.

Q4: Can this calculator be used for any compound?
A: Yes, as long as you know the number of atoms of the element and the compound's molar mass.

Q5: What's the percent composition of oxygen in water?
A: Approximately 88.89% (16/18 × 100).