Agenda: Warm-up: Explain the solvation process Review – terms, importance, “likes dissolve likes” Solubility Curves What can they tell us about solutions? Measuring concentration of solutions Peer review of lab reports Homework: Read from Chapter 15 to complete tables 3,4,7 & 8

Warm-up: Solvation Process Explain what is happening when an ionic compound is dissolved in water (called solvation or hydration) View the video - what are key steps that need? How does the water molecules interact with the ionic compound? jectfolder/flashfiles/thermochem/solutionSalt.html

Solution process

Homework: Solutions: Chapter 15 Read pp , Complete tables in notes 3. Examples of solutions 4. Size of solute particles 7. Making solutions Questions: States of Matter Summary – Due on Thursday

Why are solutions important?

6. Making Solutions: Molecules (Covalent compounds) General Rule: “Likes dissolve likes”

Likes dissolve likes Polar solvents will dissolve polar solutes Non-electrolytes – do not separate into ions Ethanol Sugar

Water cannot dissolve non-polar solutes Insoluble Examples:

Organic solvents Non-polar solvent dissolving non-polar solutes Examples: To remove oily stains in dry-cleaning Lipids will dissolve in hydrocarbon To clean oil based paints To manufacture plastics, man-made fibers, adhesives

7. Making Solutions: Factors that impact the solubility of solids in liquids Energy is involved – 2 steps Endothermic to separate solute & solvent particles Exothermics – attraction between solvent & solute particles Factors affecting solids dissolving in liquids General trend to increase solubility Chemical components of solute and solvent Intermolecular forces Temperature Particle size Agitation (amount of stirring)

9. Measuring Concentration Solubility: number of grams of solute in 100 grams of water at 20 ℃ Solubility Curves Saturated solutions Unsaturated Supersaturated lated

Solubility & Temperature Reading curves Super saturated Unsaturated Temperature Line shows the amount of solute in a saturated solution Solute (g) per 100 g H ₂ O

The video begins with a few crystals of sodium acetate placed on the lab bench. A supersaturated solution of sodium acetate is poured over the crystals providing a seed or crystallization. The salt begins to crystallize, forming a large sodium acetate structure from the precipitation of the ions out of solution. When the sodium acetate crystallizes, the oppositely charged ions are brought closer together by the crystal structure. Since formation of a crystal lattice lowers potential energy by placing like charges close together, the system releases the excess energy in the crystallization process. Thus, the structure ends up being warm to the touch from this excess energycrystal lattice

Examples of supersaturated solutions A good example of supersaturation is provided by Na 2 S 2 O 3, sodium thiosulfate, whose solubility at 25°C is 50 g Na 2 S 2 O 3 per 100 g H 2 O. If 70 g Na 2 S 2 O 3 crystals is dissolved in 100 g hot H 2 O and the solution cooled to room temperature, the extra 20 g Na 2 S 2 O 3 usually does not precipitate. The resulting solution is supersaturated; consequently it is also unstable. It can be “seeded” by adding a crystal of Na 2 S 2 O 3, whereupon the excess salt suddenly crystallizes and heat is given off. After the crystals have settled and the temperature has returned to 25°C, the solution above the crystals is a saturated solution—it contains 50 g Na 2 S 2 O 3.

Interpreting solubility curves Y axis X axis Lines If the amount needed is more or less than 100 g of H ₂O 1 g H₂0 = 1 mL H₂0

Determine the amount of solute required to make a saturated solution Amount, grams KNO 3 at 70°C NH 4 Cl at 90°C NaCl at 100°C KI at 20°C NaNO 3 at 35°C SO 2 at 50°C NH 3 at 20°C KClO 3 at 65°C KCl at 75°C NH 4 Cl at 65°C HCl at 10°C NaNO 3 at 70°C KNO 3 at 10°C

Determine the amount of solute required to make a saturated solution Amount in grams KNO 3 at 70°C140g NH 4 Cl at 90°C72g NaCl at 100°C40g KI at 20°C145g NaNO 3 at 35°C100g SO 2 at 50°C5g NH 3 at 20°C55g KClO 3 at 65°C20g KCl at 75°C50g NH 4 Cl at 65°C60g HCl at 10°C78g NaNO 3 at 70°C135g KNO 3 at 10°C

Gases What additional information is in this curve? Explain how gases are different from the other compounds? Type: Size: Temperature:

8. Making solutions: Factors that affect the solubility of gases in liquids Factors affecting gasesGeneral trends to increase solubility Temperature Pressure Think about soda (carbonated drinks)

Practice: Interpreting Solubility Curve Activity 5-5 Define: solubility (quantitative ) Saturated Precipitate

CategoryIons Except with these ions Examples Soluble cations Group 1 ions and ammonium, NH 4 + No exceptions Na 2 CO 3, LiOH, and (NH 4 ) 2 S are soluble. Soluble anions NO 3 - and C 2 H 3 O 2 - No exceptions Bi(NO 3 ) 3, and Co(C 2 H 3 O 2 ) 2 are soluble. Usually soluble anions Cl -, Br -, and I - Soluble: Exceptions: Ag + and Pb 2+ CuCl 2 is water soluble, but AgCl is insoluble. SO 4 2- Soluble Exceptions: Ba 2+ and Pb 2+ FeSO 4 is water soluble, but BaSO 4 is insoluble. Usually insoluble anions CO 3 2-, PO 4 3-, and OH - Insoluble: Exceptions: group 1 elements and NH 4 + CaCO 3, Ca 3 (PO 4 ) 2, and Mn(OH) 2 are insoluble in water, but (NH 4 ) 2 CO 3, Li 3 PO 4, and CsOH are soluble. Solubility Rules determined under specified concentration (often 0.1% molarity)

9f. Measuring Concentrations Molarity (M) by definition = Molarity = Moles of solute 1 Liter of solution Therefore: 2 molar solution = __________________ Discovery Education video Standard Deviants School Chemistry: solutions & dilutions

Molarity: moles of solute liters of solution

Molarity problems What I s the molarity of a solution in which 58 gram of NaCl are dissolved in 1.0 L of solution? What is the molarity of a solution in which 10.0 grama of silver I nitrate is dissolved in 500 mL of solution? How many grams of potassium nitrate should be used to prepare a 2.0 L of a 0.5 molar solution?

Steps needed in molarity calculations Moles For grams: Liters of solution If less than 1L ? mL = 1L Comparison __________ = moles of solute 1 liter of solution

Molarity practice To what volume should 5.0 g of KCl be diluted in order to prepare a 0.25M solution? How many grams of copper II sulfate – penta hydrate are needed to prepare 100 mL of a 0.10M solution?

9g. Dilution of concentrated solutions: V₁M₁= V₂M₂ Molarity by dilution practice problems Most reagents are sold & sorted in concentrated solutions How much concentrated 18M sulfuric acide is needed to prepare 250mL of a 6.0M solution? How much concentrated 12M hydrochloric acid is needed to prepare 100 mL of a 2.0 M solution?

To what volume should 25 mL of 15 M nitric actid be diluted to prepare a 3.0 M solution? To how much water should 50 mL of 12 M hydrochloric acid be added to produce a 4.0 M solution? To how much water should 100 mL of 18M sulfuric acid be added to prepare 1.5 M solution ?

Colligative Properties The properties of the solution that depend on the number of particles in solution, not the identity of the solute. The solvent properties will be changed. NaCl CaCl ₂ AlCl₃ Melting point depression; boiling point elevation; Vapor pressure lowering

Resources lake.com/solution.htm lake.com/solution.htm /powerpoint- list.htm ek.com/chemistrypower point/Student%20Ch%2 015%20Solutions.ppt ek.com/chemistrypower point/Student%20Ch%2 015%20Solutions.ppt m/chemistry/general/zu mdahl/world_of_chem/1 e/instructors/ppt/figures /viewindex.html

Solution process