1. Preparing and Diluting Solutions
Unit 49
Preparing and Diluting Solutions

2. Basic Principles of Preparing and Diluting Solutions
A solution is composed of two parts: a solvent and a solute.
The solvent is the substance, usually a liquid, in which a substance is dissolved.
The solute is the substance dissolved by the solvent. The solute is usually a solid concentrated substance, but it can be a liquid.

3. Basic Principles of Preparing and Diluting Solutions
When the solute is a solid and the solvent is a solution, the solute is expressed as grams (g) or an equivalent of grams and the solvent as milliliters (mL).
The strength of solutions is stated as either a ratio or a percent.
A solution with a ratio of 1:10 means that there is one part of solute in 10 parts of the solution.

4. Basic Principles of Preparing and Diluting Solutions
At times, solutions must be diluted.
A concentrated solution is used to make a weaker solution.
The concentrated solution is used as the solute.
A solvent is then added to the correct amount of concentrated solution to dilute the solution.

5. Preparing and Diluting Solutions
Example: How many milliliters (mL) of boric acid solution are needed to prepare 500 mL of 5% boric acid solution?
Use this formula to set up a proportion:

6. Preparing and Diluting Solutions
Fill in:
100 x X = 5 x 500
100X = 2,500
X = 25
Use 25 mL of boric acid as solute.

7. Practical Problem
How many milliliters (mL) of bleach are needed to prepare 100 mL of a 10% bleach solution?

8. Practical Problem Calculate the bleach in a 10% solution:
100X = 10 x 100
100X = 1,000
X = 10 mL
Use 10 mL of bleach as a solute.