Mass by volume percentage (w/v)
Defines concentration as mass of solute per 100 units volume of solution.
What is Mass by volume percentage (w/v)?
A measure of concentration that expresses the mass of a solute in grams dissolved in 100 millilitres of a solution.
Key formula / rule: Mass by Volume Percentage
Key points
- Define mass by volume percentage.
- Calculate mass by volume percentage given the mass of solute and volume of solution.
- Interpret given mass by volume percentage values.
- Differentiate % w/v from other concentration units.
Common exam trap
Confusing the volume of the solution with the volume of the solvent.
Definitions
- Term
Mass by Volume Percentage (w/v)
- Meaning
A measure of concentration that expresses the mass of a solute in grams dissolved in 100 millilitres of a solution.
- Term
Solution
- Meaning
A homogeneous mixture of two or more substances, where one is a solute and the other is a solvent.
- Term
Solute
- Meaning
The substance that is dissolved in a solvent to form a solution.
Learning objectives
Define mass by volume percentage.
Calculate mass by volume percentage given the mass of solute and volume of solution.
Interpret given mass by volume percentage values.
Differentiate % w/v from other concentration units.
Formulae
- Name
Mass by Volume Percentage
- Note
This formula calculates the percentage concentration by mass of solute per volume of solution.
- Expression
\text{% w/v} = \frac{\text{Mass of solute (g)}}{\text{Volume of solution (mL)}} \× 100
Prerequisites
Understanding of basic units of mass (grams) and volume (millilitres).
Concept of solute and solvent.
Basic arithmetic operations.
Common mistakes
Confusing the volume of the solution with the volume of the solvent.
Using incorrect units for mass or volume in the calculation.
Mistaking % w/v for % w/w or % v/v.
Assuming the density of the solution is 1 g/mL when converting to other concentration units.
Keywords
Mass by volume percentage
w/v
Concentration
Solution
Solute
Grams per millilitre
Pharmaceuticals
Medical solutions
Practice preview
What is the mass by volume percentage (% w/v) of a solution prepared by dissolving 5 grams of sodium chloride in enough water to make a final volume of 100 mL?…
easy
A doctor prescribes a medication with a concentration of 500 mg per 5 mL. What is the mass by volume percentage (% w/v) of this medication if the density of the solution is approximately 1 g/mL?…
medium
A solution is prepared by dissolving 10 grams of glucose in water to make a final volume of 250 mL. What is the mass by volume percentage (% w/v) of this solution?…
easy