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Online Molarity Calculator

Calculate the mass, volume, molar mass, or concentration of a chemical solution. Enter any three values to find the fourth.

Molarity Calculator
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g/mol

Understanding Chemical Solutions

Master the core concepts of concentration and solution preparation in the lab.

The Formula

The foundational equation for concentration is C = n / V, where C is concentration (molarity), n is the number of moles, and V is the volume in liters.

Moles & Mass

Because we can't count individual molecules easily, we measure mass using a balance. We connect mass to moles using the Molar Mass (MW): moles = mass / MW.

Lab Preparation

To make a solution, calculate the required mass, weigh it out, dissolve it in slightly less than final volume of solvent, then "top it up" to the exact final volume in a volumetric flask.

Frequently Asked Questions

What is Molarity?

Molarity (represented by the letter M) is a unit of concentration that measures the number of moles of a solute present in one liter of a solution. For example, a 1 M solution contains 1 mole of solute per liter.

How do you calculate molarity from mass and volume?

First, divide the mass of your solute by its molar mass to find the number of moles. Then, divide the number of moles by the volume of the solution in liters. The formula is: Molarity = Mass / (Molar Mass × Volume).

What is molar mass?

Molar mass is the mass of one mole of a specific substance, usually expressed in grams per mole (g/mol). You can find it by adding up the atomic masses of all the atoms in the chemical formula (found on the periodic table).

How does molarity differ from molality?

Molarity measures moles of solute per LITER of SOLUTION (volume). Molality measures moles of solute per KILOGRAM of SOLVENT (mass). Molarity changes slightly with temperature (because volume expands/contracts), while molality is temperature-independent.

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