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Solute Mass, Solution Volume & Molarity

Relate solute mass, molar mass and final solution volume to mass concentration and molarity.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A 5 g solute sample with molar mass 50 g/mol in a final volume of 0.5 L gives 0.2 M and 10 g/L, or 0.01 g/mL.

Molarity = solute mass / (molar mass × final solution volume)

Worked example

Enter these known values and leave the other values blank.

Dissolved solute mass
5 g
Solute molar mass
50 g/mol
Final solution volume
0.5 L
Mass concentration
0.01 g/mL
Molar concentration
0.2 M

Assumptions and limitations

  • Mass, molar mass, final solution volume and concentrations are positive. Use final solution volume after dissolution.
  • Concentration in g/L has the same numerical value as kg/m³. The starting mass-concentration display is g/mL, which is 1,000 times larger as a unit.
  • Volume-based concentrations can change with temperature. Specify the relevant temperature and solute composition when preparing or comparing solutions.

Common questions

Should I add the solute to exactly the entered solvent volume?

The formula uses final solution volume. Adding solute to that volume of solvent need not produce the same final volume.

Is molecular weight the same as molar mass?

Molar mass has units such as g/mol. Relative molecular mass is dimensionless; the numerical values commonly coincide when molar mass is stated in g/mol.

References

Bookify replaces the captured rounded US gallon with the exact 3.785411784-liter definition. The US fluid ounce uses one 128th of the exact US liquid gallon, replacing the rounded captured reciprocal factor.

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