8.2 Solubility and Concentration
Reading Focus
Key Concepts
How are solutions with different amounts of solute described?- What factors determine the solubility of a solute?
- What are three ways to measure the concentration of a solution?
Vocabulary
solubility
saturated solution
unsaturated solution
supersaturated solution
concentration
molarity
Reading Strategy
Previewing Copy the table below. Before you read the section, rewrite the green topic headings as how, why, and what questions. As you read, write an answer to each question.
| Question | Answer |
|---|---|
What is solubility? |
a. |
b. |
Solvent, temperature, and pressure |
c. | d. |
Have you ever prepared a pitcher of lemonade or iced tea? Fresh lemonade is a solution of water, lemon juice, and sugar. Water is the solvent. Lemon juice and sugar are the solutes.
You might be surprised at how much sugar can dissolve in water. However, there is a limit to the amount of sugar that can dissolve in a given amount of water. Once that limit is reached, no more sugar will dissolve, and you cannot make the solution taste any sweeter.
Solubility
The maximum amount of a solute that dissolves in a given amount of solvent at a constant temperature is called solubility. Solubilities are usually expressed in grams of solute per 100 grams of solvent at a specified temperature. Figure 8 lists the solubilities of some common substances in water at 20°C. Notice that table sugar is more soluble in water than table salt, which is more soluble than baking soda.
Figure 8 At a given temperature, different solutes have different solubilities in water. Calculating At 20°C, how much baking soda can dissolve in 200 grams of water?
dKnowing the solubility of a substance can help you classify solutions based on how much solute they contain. Solutions are described as saturated, unsaturated, or supersaturated, depending on the amount of solute in solution.
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