The mass volume percent (% m/v) of a solution is calculated by dividing the mass of the solute (in grams) by the volume of the solution (in milliliters) and multiplying by 100.
Formula:
% m/v = (Mass of solute (g) / Volume of solution (mL)) x 100
Explanation:
The mass volume percent expresses the concentration of a solution as the mass of the solute dissolved in a specific volume of the solution. It's a convenient way to express concentrations when dealing with solid solutes dissolved in liquid solvents.
Steps for Calculation:
- Determine the mass of the solute in grams (g).
- Determine the volume of the solution in milliliters (mL). It is crucial to measure the final volume of the solution after the solute has been dissolved, not just the volume of the solvent used.
- Divide the mass of the solute by the volume of the solution.
- Multiply the result by 100 to express the concentration as a percentage.
Example:
Let's say you dissolve 25 grams of sugar in water, and after dissolving the sugar, the final volume of the solution is 200 mL.
% m/v = (25 g / 200 mL) x 100 = 12.5%
This means the solution is a 12.5% mass/volume solution of sugar.
Important Considerations:
- Units: Ensure the mass is in grams (g) and the volume is in milliliters (mL).
- Final Volume: The volume used in the calculation is the final volume of the solution, not just the volume of the solvent added. Dissolving the solute will often change the volume slightly.
