Percentage Concentration to Molarity Calculator
Free Percentage concentration molarity Calculator for mixtures & solutions. Enter variables to compute results with formulas and detailed steps.
Reviewed by Manoj Kumar, Mathematics Educator
Formula
M = (% x density x 10) / molar mass
Molarity equals the weight percentage multiplied by the solution density in g/mL multiplied by 10, divided by the molar mass of the solute in g/mol. The factor of 10 arises from unit conversion between grams per 100 grams and grams per liter.
Worked Examples
Example 1: Concentrated HCl to Molarity
Problem:Convert 37% HCl (density 1.19 g/mL, molar mass 36.46 g/mol) to molarity.
Solution:M = (37 x 1.19 x 10) / 36.46\nM = 440.3 / 36.46\nM = 12.07 mol/L
Result:Molarity = 12.07 M
Example 2: Concentrated H2SO4 to Molarity
Problem:Convert 96% sulfuric acid (density 1.84 g/mL, molar mass 98.079 g/mol) to molarity.
Solution:M = (96 x 1.84 x 10) / 98.079\nM = 1766.4 / 98.079\nM = 18.01 mol/L
Result:Molarity = 18.01 M
Frequently Asked Questions
How do you convert percentage concentration to molarity?
To convert percentage concentration to molarity, use the formula M = (% x density x 10) / molar mass. The percentage is the weight-by-weight (w/w) percent of the solute in the solution. The density is the overall density of the solution in grams per milliliter. The molar mass is the molecular weight of the solute in grams per mole. The factor of 10 converts the units so the result is in moles per liter.
What is the difference between molarity and molality?
Molarity (M) is defined as moles of solute per liter of solution, while molality (m) is moles of solute per kilogram of solvent. Molarity depends on the volume of the solution, which changes with temperature, making it temperature-dependent. Molality depends only on mass, so it remains constant regardless of temperature. For dilute aqueous solutions, molarity and molality are approximately equal because the density of water is close to 1 kg/L.
What are common percentage concentrations for laboratory reagents?
Common laboratory reagents have well-known percentage concentrations. Concentrated hydrochloric acid is typically 36-38% with a density of 1.19 g/mL. Concentrated sulfuric acid is about 95-98% with a density of 1.84 g/mL. Concentrated nitric acid is 68-70% with a density of 1.42 g/mL. Glacial acetic acid is nearly 100% with a density of 1.05 g/mL. Knowing these values allows quick conversion to molarity for dilution calculations.
What is the difference between w/w%, w/v%, and v/v% concentration?
Weight-by-weight (w/w%) expresses grams of solute per 100 grams of solution and is independent of temperature since mass does not change. Weight-by-volume (w/v%) expresses grams of solute per 100 mL of solution and is commonly used in biology and medicine. Volume-by-volume (v/v%) expresses milliliters of solute per 100 mL of solution and is used for liquid-in-liquid mixtures like alcohol solutions. Percentage Concentration to Molarity Calculator uses w/w% because it is the most common way concentrated reagent concentrations are reported on chemical labels.
References
Reviewed by Manoj Kumar, Mathematics Educator · Editorial policy