UNIT 6 SOLUTIONS AND GASES 6.2 What factors affect solubility? April 8, 2010 AIM: What are the factors that affect solubility? DO NOW: List the factors that affect the rate of reaction. What are the two parts of a solution? Nature of the reactant Concentration Surface area Pressure Catalyst Temperature SOLUTE and SOLVENT  

SOLUTION CHECKLIST Homogeneous mixtures Clear and do not disperse light Can have color Do not settle on standing Pass through a filter

DEFINITIONS Directions: Look up the definitions of the following words: SOLUBILITY SOLUBLE INSOLUBLE

WORD DEFINITION SOLUBILITY How much of a solute will Dissolve in a certain amount Of solvent SOLUBLE Materials with high solubility INSOLUBLE Materials with low solubility

FACTORS THAT AFFECT SOLUBILITY EFFECT (READ: as temp increases, solubility of solids….) EXCEPTIONS TEMPERATURE PRESSURE POLARITY Gases react in Opposite way: T gases T solids No effect on Solubility of Solids or liquids Has an effect On gases: P gases Polar dissolves polar Nonpolar dissolves nonpolar

A little more on polarity TYPE DEFINITION POLAR NONPOLAR Symmetrical molecules - Due to distribution of charge Asymmetrical molecules - Due to distribution of charge

TRY THE DEMONSTRATION

“LIKE DISSOLVES LIKE” Solute Type Nonpolar solvent Polar Solvent Soluble Polar soluble nonpolar insoluble insoluble soluble ionic insolube

EXAMPLE Greases, which are nonpolar, won’t easily wash off our hands in water, which is polar. Soaps have one end that is polar, which allows the soap to dissolve in water. The other end of the soap is nonpolar, and grease will dissolve in it.

BRAIN STRETCHING What kind of solvent will dissolve a polar solute? Give examples. 2. What kind of solvent will dissolve a nonpolar solute? Give examples. 3. Waterproof mascara won’t wash off with water, what might be a good substance to use to wash it off your face? Why? POLAR SOLVENT Ex. Water NONPOLAR SOLVENT Ex. GREASE, any molecule nonpolar Oil or soap. Because the mascara is NONPOLAR and oil is NONPOLAR

4. What happens to the solubility of solids and gases when the temperature of a solution is increased? 5. What happens to the solubility of solids and gases when the pressure on a solution is increased? 6. What does the phrase “like dissolves like” tell you about when something will dissolve and when it will not? Temperature increase causes solubility of solids to increase and solubility of gases to decrease. Pressure increase does not change solubility of solids but it increases the solubility of gases. Polar will dissolve Polar Nonpolar will dissolve Nonpolar

7. In terms of distribution of charges, why is it that a polar substance will dissolve in a polar solvent, but not in a nonpolar solvent? You may need to review the definitions of polar and nonpolar to answer this question. Because the attractive forces between two polar substances will be greater due to the uneven distribution of charge. Attractive forces between a nonpolar and a plar substance are not strong enough.

INDEPENDENT PRACTICE Complete the Independent Practice PLACE COMPLETED IP IN HOMEWORK BIN