To calculate the percentage of a solution, divide the mass of the solute by the mass of the solution (which is the solute plus the solvent), and then multiply by 100.
Here's a more detailed breakdown:
Understanding the Components
- Solute: The substance being dissolved (e.g., sugar in water).
- Solvent: The substance doing the dissolving (e.g., water).
- Solution: The mixture formed when the solute dissolves in the solvent (e.g., sugar water).
The Formula
The formula for calculating the percentage of a solution is:
Percentage (%) = (Mass of Solute / Mass of Solution) * 100
Steps for Calculation
- Determine the mass of the solute. This is the weight of the substance you are dissolving. For example, let's say you have 20 grams of sugar.
- Determine the mass of the solution. Remember, the mass of the solution is the total mass of the solute plus the solvent. If you dissolve the 20 grams of sugar in 80 grams of water, the mass of the solution is 20g + 80g = 100g.
- Divide the mass of the solute by the mass of the solution. In our example: 20g / 100g = 0.2
- Multiply the result by 100. 0.2 * 100 = 20%
Example
Let's say you dissolve 25 grams of salt in 125 grams of water. What is the percentage concentration of the salt solution?
- Mass of Solute (Salt): 25 grams
- Mass of Solvent (Water): 125 grams
- Mass of Solution (Salt + Water): 25 grams + 125 grams = 150 grams
- Percentage Calculation: (25 grams / 150 grams) * 100 = 16.67%
Therefore, the solution is a 16.67% salt solution.
Important Considerations
- Units: Ensure that the mass of the solute and the mass of the solution are in the same units (e.g., grams, kilograms, pounds).
- Accurate Measurement: Use accurate measuring tools to determine the mass of the solute and solvent for a precise percentage calculation.
- Volume vs. Mass: This calculation is for mass percentage. If you're working with volumes, you'll need to use a different formula (volume of solute / volume of solution) * 100, and be aware that volumes are not always additive.
