Molarity Calculator

Calculate Mass, Concentration or Volume

The BioCrick molarity calculator is a laboratory calculation tool for preparing solutions from compounds with a known molecular weight.

It can be used to calculate:

• the mass of a compound required to prepare a solution with a known volume and concentration;
• the volume of solution required to dissolve a known mass of compound to a desired concentration;
• the concentration of a solution resulting from a known mass of compound in a specified volume.

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Enter any three known values and use the calculator to determine the remaining value.

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The Molarity Calculator Equation

The molarity calculation is based on the relationship between mass, concentration, volume, and molecular weight:

Mass (g) = Concentration (mol/L) × Volume (L) × Molecular Weight (g/mol)

The equation can also be rearranged to calculate concentration or volume:

• Concentration = Mass / (Volume × Molecular Weight)
• Volume = Mass / (Concentration × Molecular Weight)

Molarity Calculation Example

What mass of a compound is required to prepare 10 mL of a 10 mM stock solution when the molecular weight of the compound is 147.23 g/mol?

Convert the concentration and volume to base SI units:

• Concentration = 10 mM = 0.010 mol/L
• Volume = 10 mL = 0.010 L
• Molecular weight = 147.23 g/mol

Therefore:

Mass = 0.010 mol/L × 0.010 L × 147.23 g/mol = 0.014723 g = 14.723 mg

1. Enter 147.23 in the Molecular Weight (MW) field.
2. Enter 10 in the Concentration field and select millimolar.
3. Enter 10 in the Volume field and select milliliter.
4. Click Calculate.
5. The calculated mass is 14.723 mg.