Section 2 – pg 262 Concentration and Solubility Chapter 7 Section 2 – pg 262 Concentration and Solubility

Pg 262 Concentration 43 gallons of maple sap -> 1 gallon of maple syrup They change the concentration of the solute in the solvent by evaporating the water leaving a sweeter solution Fun fact: maple syrup is yummy

Changing Concentration Pg 263 Changing Concentration Concentrated Solution: a lot of solute dissolved in a certain amount of solvent Dilute Solution: only a little solute dissolved in a certain amount of solvent

Measuring Concentration Pg 263 Measuring Concentration To measure concentration, you compare the amount of solute to the total amount of solution Sunny D – 568 grams of real juice 15% Concentration 3785 grams of SunnyD

Pg 263 Solubility Solubility: a measure of how much solute can dissolve in a solvent at a given temperature Unsaturated Solution: when you can dissolve more solute Saturated Solution: when you cannot dissolve more solute

Working with Solubility Pg 264 Working with Solubility The solubility of a substance tells you how much solute you can dissolve before a solution becomes saturated

Pg 264 Using Solubility You can identify a substance by its solubility b/c it is a characteristic property of matter

Factors Affecting Solubility Pg 264 Factors Affecting Solubility Factors that affect the solubility of a substance include pressure, the type of solvent, and temperature

Pg 265 Pressure Increasing the pressure increases the solubility of gases Soda is carbonated due to carbon dioxide being added under pressure

Solvents Pg 265 Some solvents and solutes are not compatible Polar compounds and nonpolar compounds do not mix very well (like oil and water)

Pg 265 Solvents For liquid solutions, the solvent affects how well a solute dissolves (like dissolves like) Ionic and polar compounds usually dissolve in polar solvents You can use water and soap to dissolve water-based paints Nonpolar compounds usually dissolve in nonpolar solvents Oil based paints require a nonpolar solvent, like turpentine

Pg 266 Temperature For most solids, solubility increases as the temp. increases This is how we can make rock candy Unlike most solids, gases become less soluble in a liquid when the temp. of the liquid goes up Warm soda tastes “flat” b/c less carbon dioxide is able to stay dissolved at the warmer temp.

Supersaturated Solution Pg 267 Supersaturated Solution Supersaturated Solution has more dissolved solute than is predicted by its solubility at the given temp. When you drop a crystal of solute into a supersaturated solution, the extra solute will come out of the solution

Chapter 7 Section 2 Homework – pg 267

1A. What is concentration?

1B. What quantities are compared when the concentration of a solution is measured?

1C. Solution A contains 50g of sugar. Solution B contains 100g of sugar. Can you tell which solution has a higher sugar concentration? Explain.

2A. What is solubility?

2B. How can solubility help you identify a substance?

2C. Look back at the table in Fig. 7 2C. Look back at the table in Fig. 7. At 0oC, about how many times more soluble in water is sugar than salt?

3A. What are three factors that affect solubility?

3B. How does temp. affect the solubility of most solids?

3C. When you heat water and add sugar, all of the sugar dissolves 3C. When you heat water and add sugar, all of the sugar dissolves. When you cool the solution, some sugar comes out of the solution. Explain why this happens.