1. Concentration and Solubility Lesson 12

2. Activator Think of the sap of a maple tree and pancake syrup
Which one is sweeter and why?
They differ in their concentration  amount of solute (sugar) dissolved in a certain amount of solvent (water)
Sap is a dilute solution  only has a little solute dissolved in the solvent
Syrup is a concentrated solution  has a lot of solute dissolved in a solvent

3. Concentrate Concentrate: amount of solute dissolved in a solvent
Dilute Solution: little solute dissolved into solvent
Concentrated Solution: A lot of solute dissolved into solvent

4. Changing Concentrate You can change concentrate by adding more solute
Or by adding or removing solvent
Fruit juice is often made from concentrate  Have to add water to it

5. Measuring Concentrate
Compare the amount of solute to the amount of solvent or to the total amount of solution
Report concentration as the percent of solute in solution by volume or mass
A solution contains 10 grams of solute dissolved in 100 grams of solution
10g / 100g x 100 % = 10%
A solution contains 12 grams of solute in 36 grams of solution. What’s it concentrate?
12/36=.333 x 100 = 33 %

6. Solubility Suppose you’re adding sugar to a glass of ice tea
Is there a limit to how “sweet” you can make it?
Yes
Solubility: measure of how much solute can dissolve in a solvent at a given temperature
Saturated Solution: so much solute has been added that no more can be dissolved
Unsaturated Solution: Solutes continue to dissolve in solvents
If a substance is dissolved in water, a question you may ask is, “”How much can dissolve”?
At a certain point, no matter how much your stir the tea, no more sugar will dissolve

7. Solubility
Solubility of a substance tells you how much solute you can dissolve before the solution comes saturated
Used to help identify a substance it is a characteristic property of matter
You see a while of white powder on the kitchen table. You don’t know whether its salt or sugar and you don’t want to taste it. You could measure the solubility instead. You can dissolve more sugar in water then salt
Sugar 180 g per 100 g of water
Salt 35.7 g per 100 g of water

8. Factors Affecting Solubility
Which can dissolve more sugar? Iced tea or Hot tea?
Factors that affect Solubility
Pressure
Type of solvent
Temperature

9. Factors Affecting Solubility
Pressure
Solvents
Affects the solubility of gases
The higher the pressure of gas over solvent, the more gas can be dissolved
Carbonated drinks
To increase CO2 concentration in soft drinks, the gas is added under pressure
Opening the bottle reduces the pressure and gas escapes
Some mixtures don’t mix
Oil and vinegar
“Like dissolves like”
How it’s Made: Soda
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10. Factors Affecting Solubility
Temperature
Supersaturated Solution: mixture than has more dissolved solute than is predicted by its solubility at the given temperature
For SOLIDS solubility increases as the temperature increases
Cooks use increased Solubility when making desserts like rock candy, fudge, and peanut brittle
For GASES solubility decreases as temperature increases
CO2 will dissolve more in cold water than hot water

11. Activator 1. What is concentration?
2. What quantities are compared when the concentration of a solution is measured?
3. Solution A contains 50g of sugar. Solution B contains 100g of sugar. Can you tell which solution has a high sugar concentration? Explain.
4. What is solubility?
5. How can solubility help you identify a substance?
6. What are the three factors that affect solubility?
7. How does temperature affect the solubility of most solids?