Mass Percent Calculator
Our mixtures & solutions calculator computes mass percent accurately. Enter measurements for results with formulas and error analysis.
Reviewed by Manoj Kumar, Mathematics Educator
Formula
Mass % = (mass of solute / mass of solution) * 100
Mass percent is the ratio of solute mass to total solution mass expressed as a percentage. The solution mass is the sum of solute mass and solvent mass.
Worked Examples
Example 1: Salt Water Solution
Problem:Calculate the mass percent of a solution made from 15 g NaCl dissolved in 485 g water.
Solution:Total mass = 15 + 485 = 500 g\nMass percent = (15 / 500) * 100 = 3.00%\nMass fraction = 0.03\nPPM = 30,000
Result:Mass percent = 3.00%
Example 2: Sulfuric Acid
Problem:A 250 g sulfuric acid solution contains 49 g of H2SO4. Find the mass percent.
Solution:Mass percent = (49 / 250) * 100 = 19.60%\nSolvent mass = 250 - 49 = 201 g\nMass fraction = 0.196
Result:Mass percent = 19.60%
Frequently Asked Questions
What is mass percent and how is it calculated?
Mass percent (also called weight percent or w/w%) is the mass of solute divided by the total mass of the solution, multiplied by 100. For example, if 5 grams of salt is dissolved in 95 grams of water, the total solution mass is 100 grams and the mass percent is (5/100)*100 = 5%. Mass percent is temperature-independent unlike volume-based concentrations, making it useful for solutions where temperature varies. It is one of the most common ways to express concentration in chemistry, especially for solid solutes.
What is the difference between mass percent and mass fraction?
Mass fraction is the ratio of solute mass to total solution mass expressed as a decimal (0 to 1), while mass percent is the same ratio multiplied by 100 to express it as a percentage (0% to 100%). For example, a 5% NaCl solution has a mass fraction of 0.05. Both convey the same information in different formats. Mass fraction is preferred in thermodynamic calculations and physical chemistry, while mass percent is more commonly used in practical laboratory and industrial settings because percentages are more intuitive for most people.
How do I convert between mass percent and molarity?
To convert mass percent to molarity, you need the solution density (d, in g/mL) and the molar mass of the solute (M, in g/mol). The formula is: Molarity = (mass percent * density * 10) / molar mass. For example, 37% HCl with density 1.19 g/mL: Molarity = (37 * 1.19 * 10) / 36.46 = 12.08 M. The factor of 10 converts from percent and mL to the proper units. This conversion is essential in analytical chemistry when preparing solutions from concentrated stock reagents.
What are parts per million (ppm) and how do they relate to mass percent?
Parts per million (ppm) equals mass percent multiplied by 10,000. So 1% = 10,000 ppm, and 1 ppm = 0.0001%. PPM is used for very dilute solutions where expressing concentration as a percentage would yield inconveniently small numbers. For aqueous solutions at low concentrations, 1 ppm is approximately equal to 1 mg/L because the density of dilute aqueous solutions is close to 1 g/mL. Environmental standards for water quality and air pollution are typically expressed in ppm or parts per billion (ppb), where 1 ppm = 1000 ppb.
References
Reviewed by Manoj Kumar, Mathematics Educator · Editorial policy