Concentration and Solubility Lesson 12

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

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

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

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 %

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

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

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

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 https://www.youtube.com/watch ?v=_oqyTKmIpxk

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

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?