The mass of solute divided by the volume of solution is a fundamental measure of concentration, specifically known as mass/volume concentration or mass concentration.
Understanding Mass/Volume Concentration
This ratio directly quantifies the amount of solute (typically in grams) present within a given volume of the entire solution (often in milliliters or liters). It is a vital concept across various scientific disciplines, including chemistry, biology, and medicine, for accurately preparing solutions of desired strengths.
Relationship to Mass by Volume Percentage
As detailed in the provided reference, the mass/volume concentration is directly related to the "Mass by volume percentage" through a simple formula:
Mass by volume percentage = (mass of solute / volume of solution) x 100
Therefore, to find the "mass of solute divided by volume of solution"—which represents the mass/volume concentration—you can rearrange the formula:
Mass of solute / Volume of solution = Mass by volume percentage / 100
This implies that the mass/volume concentration is the fractional or decimal equivalent of the mass by volume percentage before it is multiplied by 100.
Practical Applications and Examples
This type of concentration measurement is extensively used, particularly where the solute is a solid measured by mass and the solution is a liquid measured by volume.
- Medical Saline Solutions: A prime example cited in the reference is the preparation of medical saline.
- A 0.9 percent (w/v) NaCl solution signifies that there are 0.9 grams of NaCl (solute) per 100 mL of solution.
- In this scenario, the
mass of solute / volume of solutionratio is0.9 g / 100 mL = 0.009 g/mL. - Multiplying
0.009 g/mLby 100 yields0.9% (w/v), which is the mass by volume percentage.
- Laboratory Reagents: Researchers and lab technicians frequently use mass/volume concentration to formulate precise reagents, buffers, and stock solutions essential for experiments and analyses.
Common Units for Mass/Volume Concentration
The units for mass/volume concentration are typically expressed as a mass unit per volume unit, reflecting the components measured.
| Component | Common Mass Units | Common Volume Units | Typical Concentration Units |
|---|---|---|---|
| Solute Mass | Grams (g) | Milliliters (mL) | g/mL, g/L |
| Milligrams (mg) | Liters (L) | mg/mL, mg/L | |
| Kilograms (kg) | kg/L | ||
| Solution Volume |
Key Insights
- It provides a straightforward way to express the density of the solute within the solution.
- It serves as the foundational ratio for calculating the Mass by volume percentage.
- Its accuracy is critical for ensuring the correct strength and efficacy of solutions in various applications.
