Percent Solution Calculator
Compute percent solution using validated scientific equations. See step-by-step derivations, unit analysis, and reference values.
Reviewed by Manoj Kumar, Mathematics Educator
Formula
% (w/v) = (mass solute / volume solution) x 100
Percent solution expresses concentration as a ratio of solute to solution. Weight/volume uses grams per 100 mL, weight/weight uses grams per 100 grams, and volume/volume uses mL per 100 mL.
Worked Examples
Example 1: Saline Solution (w/v)
Problem:Calculate the percent (w/v) of a solution with 9 g NaCl in 1000 mL of solution.
Solution:% (w/v) = (9 g / 1000 mL) x 100\n% (w/v) = 0.009 x 100\n% (w/v) = 0.9%
Result:0.9% (w/v) — Normal saline
Example 2: Ethanol Solution (v/v)
Problem:What is the percent (v/v) of a solution with 40 mL ethanol in 100 mL total solution?
Solution:% (v/v) = (40 mL / 100 mL) x 100\n% (v/v) = 0.4 x 100\n% (v/v) = 40%
Result:40% (v/v) — Typical vodka concentration
Frequently Asked Questions
What is a percent solution?
A percent solution expresses the amount of solute dissolved in a solution as a percentage. There are three types: weight/volume (w/v) percent is grams of solute per 100 mL of solution, weight/weight (w/w) percent is grams of solute per 100 grams of solution, and volume/volume (v/v) percent is milliliters of solute per 100 mL of solution. The type used depends on whether the solute is a solid or liquid and whether the measurement is by mass or volume.
How do you prepare a percent solution in the lab?
To prepare a weight/volume percent solution, weigh the required amount of solute and dissolve it in solvent, then add more solvent to reach the final desired volume. For example, to make 500 mL of a 5% (w/v) NaCl solution, dissolve 25 g of NaCl in water and bring the total volume to 500 mL using a volumetric flask. It is important to add solvent to the final volume rather than adding a specific volume of solvent, because the solute takes up space and changes the total volume.
What is the difference between w/v, w/w, and v/v percent?
Weight/volume (w/v) percent uses grams of solute per 100 mL of solution and is most common in biology and medicine. Weight/weight (w/w) percent uses grams of solute per 100 grams of total solution and is common in industrial chemistry because mass does not change with temperature. Volume/volume (v/v) percent uses milliliters of solute per 100 mL of solution and is used for liquid-in-liquid mixtures like alcohol solutions. Each type answers the question of concentration differently.
How do you convert percent solution to molarity?
To convert a w/v percent solution to molarity, divide the concentration in grams per liter by the molar mass of the solute. Since w/v percent means grams per 100 mL, multiply by 10 to get grams per liter, then divide by molar mass. For a w/w percent solution, you also need the density of the solution to convert mass to volume. The formula is M = (% w/w x density x 10) / molar mass.
References
Reviewed by Manoj Kumar, Mathematics Educator · Editorial policy