This molarity calculator estimates the molar concentration of a solution by using the mass, volume and molecular weight. You can read more on the molar concentration and how to calculate the number of moles for a solution below the form.

Complete any of the three fields to discover the fourth value!
Molecular Weight:

How does this molarity calculator work?

This is a great chemistry tool for those who need to determine a solution’s molar concentration from the mass, volume and molecular weight. There are  four components in the equation therefore there are four fields in the molarity calculator. To compute any of the elements in the molarity equation you need to input the other three and choose the desired measurement unit.

  • Volume – expressed in either liters, milliliters or microliters;
  • Mass – expressed in either grams, milligrams, micrograms;
  • Molecular weight – expressed in g/mol
  • Concentration – expressed in either molar, milimolar, micromolar, nanomolar, picomolar or femtomolar.

What is the molarity?

This is the same with molar concentration and represents the concentration of a solute in a solution. It is defined as the number of moles in a solution. Unit of measurement : SI: [mol/L] The concentration may also be expressed in different fractions of the molar concentration such as mmol/L (mM), μmol/L (μM), nmol/L (nM), pmol/L (pM). Here are the conversions:

1 mol/L (M) equals to
1,000 mmol/L (mM)
1,000,000 µmol/L (µM)
109  nmol/L (nM)
1012 pmol/L (pM)

How to calculate the number of moles?

The number of moles represents the fraction: mass of the compound / molecular weight of the compound.

For example:

To convert grams to moles, the molecular weight of the solute is needed. From the periodic table the molar masses of the compounds will be extracted. For KMnO4:
Molar mass of K = 39.1 g
Molar mass of Mn = 54.9 g
Molar mass of O = 16.0 g
Molar mass of KMnO4 = 39.1 g + 54.9 g + (16.0 g x 4)
Molar mass of KMnO4 = 158.0 g

What other calculations you can do with the molarity calculator?

  • mass of a compound of a solution calculation:

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

  • volume of a solution calculation:

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

  • molecular weight of a solvent in a solution calculation:

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

26 Mar, 2015