Percent Composition Calculator

Percent composition is a way of expressing the relative amount of each element in a chemical compound as a percentage of the total mass. It tells us what proportion of a compound's mass is made up of each element. For example, in water (H2O), we can calculate what percentage of the total mass comes from hydrogen and what percentage comes from oxygen. This is particularly useful in chemistry for verifying the purity of compounds and understanding their composition.

1. Enter the molecular formula of your compound (e.g., H2O for water) 2. Use proper capitalization (first letter capitalized for elements) 3. Include numbers as subscripts (e.g., H2O, not H₂O) 4. Click 'Calculate' to see: • The percent composition of each element • The molar mass of the compound • The mass contribution of each element The calculator supports most common elements and handles complex formulas like Ca(OH)2.

The calculator provides three key pieces of information: 1. Total Molar Mass: The sum of all atomic masses in the compound 2. Element Composition: The percentage by mass of each element 3. Individual Masses: The mass contribution of each element in g/mol For example, in H2O: • Hydrogen: 11.19% • Oxygen: 88.81% These percentages always sum to 100% and represent the mass proportion of each element.

Percent composition calculations are essential in: • Quality Control: Verifying the purity of chemical compounds • Drug Development: Ensuring correct pharmaceutical formulations • Food Chemistry: Analyzing nutritional content • Environmental Analysis: Determining pollutant concentrations • Materials Science: Developing new materials with specific compositions Chemists use these calculations daily to maintain quality standards and develop new products.

The basic formula for percent composition is: Percent of element = (mass of element × number of atoms × 100%) ÷ molar mass of compound For example, to find the percent of hydrogen in H2O: 1. Mass of H = 1.008 g/mol 2. Number of H atoms = 2 3. Molar mass of H2O = (2 × 1.008) + 15.999 = 18.015 g/mol 4. Percent H = (1.008 × 2 × 100%) ÷ 18.015 = 11.19%

• Always use proper chemical formulas with correct capitalization • Double-check your input for common mistakes (like HCL instead of HCl) • Remember that percentages should add up to 100% • Consider significant figures in your final answer • For complex molecules, break them down into smaller parts If your percentages don't add up to 100%, check your formula for errors.