Percent Purity Calculator

Percent Purity Calculator

What is Percent Purity?

Percent purity is a measure used in chemistry to express the concentration of a desired substance within an impure sample. In real-world applications, it's very rare to have a 100% pure chemical. Samples often contain byproducts, residual solvents, or other contaminants.

Calculating the percent purity is crucial for accurate chemical reactions, manufacturing, and quality control. It tells you what percentage of your sample's total mass is actually the compound you care about.

Formulas Used

  1. To find Percent Purity:
    % Purity = (Pure Mass / Total Mass) * 100
  2. To find the Mass of Pure Compound:
    Pure Mass = Total Mass * (% Purity / 100)

Frequently Asked Questions

Why is my pure mass different from my total mass?

The "total mass" refers to the entire weight of the sample you have, including the desired compound *and* any impurities. The "pure mass" is the weight of *only* the desired compound. By definition, the pure mass will always be less than or equal to the total mass.

What are common impurities?

Impurities can be anything other than your target compound. Common examples include water (moisture), unreacted starting materials, byproducts from a chemical reaction, dust, or residual solvents used during the manufacturing or purification process.

Can percent purity be over 100%?

No, percent purity cannot be over 100%. A value of 100% would mean the sample is perfectly pure with zero impurities. If a calculation or measurement suggests a purity over 100%, it almost always indicates a measurement error (e.g., a faulty scale, or the sample is still wet when it should be dry).