Calculate pure-solute volume, density, molar mass, or molarity using the measured final solution volume. Solution density alone is insufficient to determine solute concentration.
mL To mol/L Formula
The following formula calculates molarity from pure-solute volume and density, molar mass, and the measured final solution volume. It assumes complete dissolution with no chemical reaction.
Variables:
- M is the molarity in mol/L
- V is the pure-solute volume in mL
- D is the pure-solute density in g/mL
- M_m is the solute molar mass in g/mol
- V_f is the measured final solution volume in L
Multiply pure-solute volume by its density to obtain solute mass, divide by molar mass to obtain moles, then divide by the final solution volume in liters. Do not substitute solution density for pure-solute density.
| Volume (mL) | Molarity (mol/L) |
|---|---|
| 1 | 0.01711157 |
| 2 | 0.03422313 |
| 5 | 0.08555784 |
| 10 | 0.1711157 |
| 15 | 0.2566735 |
| 20 | 0.3422313 |
| 25 | 0.4277892 |
| 30 | 0.513347 |
| 50 | 0.8555784 |
| 75 | 1.283368 |
| 100 | 1.711157 |
| 150 | 2.566735 |
| 200 | 3.422313 |
| 250 | 4.277892 |
| 300 | 5.13347 |
| 400 | 6.844627 |
| 500 | 8.555784 |
| 750 | 12.83368 |
| 1000 | 17.11157 |
| 2000 | 34.22313 |
| *Illustrative values, not NaCl preparation data. Assumes a pure solute with density 1.00 g/mL and molar mass 58.44 g/mol, dissolved to a measured final solution volume of 1.00 L. Molarity = (ρ × V) / (M_m × V_f), with V in mL and V_f in L. | |
What is Molarity?
Molarity, also known as molar concentration, is a measure of the concentration of a solute in a solution. It is defined as the number of moles of solute per liter of solution. Molarity is commonly used in chemistry to express the concentration of a chemical solution. The unit of molarity is mol/L, which indicates the number of moles of solute present in one liter of solution.
How to Calculate Molarity?
The following steps outline how to calculate the molarity.
- First, determine the pure-solute volume in mL (V) and the measured final solution volume in liters (V_f).
- Next, determine the pure-solute density in g/mL (D), not the solution density.
- Next, determine the molar mass of the solute in g/mol (M_m).
- Finally, calculate the molarity using the formula M = (V * D) / (M_m * V_f).
- After inserting the values and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Pure-solute volume (V) = 100 mL; final solution volume (V_f) = 1.00 L
Pure-solute density (D) = 1.2 g/mL
Molar Mass (M_m) = 60 g/mol
Molarity = (100 × 1.2) / (60 × 1.00) = 2.00 mol/L.
