As you come in, The Materials: –Paper and pencil –Pick up calendar, assessment plan, and practice packet The Plan: –Self-Assessment: Cumulative Quiz 7 –Visual/Auditory Activity: Solubility notes, including polarity, solubility rules, exceptions to rules, and solubility graphs –Collaborative Partners: Interpreting Graphics WS – Solubility Graphs –Individual Practice: Complete Interpreting Graphics WS –Practice Packet: “Reading Solubility Graphs” and “Worksheet: Solubility Graphs” The Assessment: –Solubility Graph Quiz- Wednesday –Concentration Quiz - Friday Musical Theme: Motown Monday

Georgia Performance Standard SC7: Students will characterize the properties that describe solutions and the nature of acids and bases.

The Water Molecule Triatomic Covalent Polar bonds & polar overall Bent at 105° angle

Intermolecular Forces Polar molecules are attracted to one another by dipole forces Water is attracted to other water molecules by a special dipole force, a hydrogen bond

Water Solutions “Chemically pure water never exists in nature because water dissolves so many substances.” textbook Universal solvent Aqueous solutions

Water Solutions Ionic compounds most readily dissolve in water due to extreme polarity Polar covalent compounds also dissolve in water Nonpolar compounds don’t

Solvation of Ionic Compounds

A Few Exceptions... Remember the solubility rules... In some ionic compounds, the ions are so attracted to each other that they won’t break apart and dissolve. These are INSOLUBLE ionic compounds.

Solvation of Covalent Compounds Covalent compounds do NOT break apart in water when dissolving. Solvation of covalent compounds means that each solute molecule is surrounded by water molecules.

Conductors In general, aqueous solutions of ionic compounds are electrolytes. Generally, aqueous solutions of covalent compounds are nonelectrolytes.

As you come in, The Materials: –Paper, calculator, practice packet and pencil The Plan: –Opening Activity: Go over Unit 8 Test –Self-Assessment: Review Solubility Graph, Answer questions in packet and on Interpreting Graphics WS –Visual/Auditory Activity: –Concentrations notes, including molarity and molality –Individual Practice: Molarity & Molality Practice –15-2 Practice Problems WS 1-5, 7, 9, 13, 17 The Assessment: –Solubility Graph Quiz- Wednesday –Concentration Quiz - Friday Musical Theme: 2-Step Tuesday

Solution Vocabulary Solute: Dissolves in the solvent Soluble: Able to be dissolved in the solvent (applicable to any states of matter) Insoluble: Unable to be dissolved in the solvent (applicable to any states of matter) Miscible: Able to be dissolved in the solvent (applicable to liquid/liquid solutions) Immiscible: Unable to be dissolved in the solvent (applicable to liquid/liquid solutions)

Solubility Vocab Unsaturated: less than maximum amount of solute is dissolved in the solvent Saturated: maximum amount of solute is dissolved in the solvent Supersaturated: special conditions have been created to dissolve more than maximum amount of solute in the solvent

Determines IF Solute Will Dissolve... The nature of the solvent and solute governs whether a solute will solvate in a particular solvent. Specifically, the nature of the intramolecular bond. Polar molecules will solvate with polar molecules. Nonpolar molecules will solvate with nonpolar molecules. BUT, polar and nonpolar will not form solutions together.

Determines Speed of Dissolving 1.Agitation: Create more collisions mechanically 2.Temperature: More kinetic energy creates more collisions 3.Surface Area: Dissolving process is a surface phenomenon, the more surface of the solute that is exposed the faster the solvation BRING SOLUTE IN CONTACT WITH SOLVENT

Determines How Much Will Dissolve 1.Temperature: solubility of solid solute increases as the temp. increases; solubility of gaseous solute decreases as temp increases ex. Hot water bubbles, thermal pollution 2. Pressure: solubility of gaseous solute increases as the pressure increases -Henry’s Law ex. Soft drinks SOLUBILITY: HOW MUCH WILL DISSOLVE

Temperature & Solubility Higher the temperature, the more solid will dissolve in a liquid Higher the temperature, the less gas will dissolve in a liquid

Henry’s Law: Pressure & Solubility At a given temperature, the solubility of a gas is proportional to the pressure of the gas above the liquid. Page 506 The higher the pressure, the more carbon dioxide will dissolve in the syrup giving a less “flat” taste.

Solubility Graph

Concentration of Solutions The concentration of a solution is a measure of how much solute is dissolved in a specific amount of solvent or solution. Molarity: most common units of solution concentration; # of moles solute dissolved in one liter of the solution

Molarity: moles of solute liter of solution If given grams, remember to change it to moles.

Example 15.3 (page 531) Calculate the molarity of a solution prepared by dissolving 11.5 g of solid NaOH in enough water to make 1.50L of solution. Example 15.4 (page 532) Calculate the molarity of a solution prepared by dissolving 1.56 g of gaseous HCl into enough water to make 26.8 mL of solution.

molality: moles of solute kg of solvent If given grams, remember to change it to moles. The most common concentration term in chemistry is Molarity (M), but chemists also report concentration in molality (m) sometimes.

The front of the last page in the calculations packet refers to Molality. Complete 1 (a), 2 (a), 3 (b), and 4 (b). NOTE: Questions 3 and 4 will require you to manipulate the equation. Question 4 might even require that you change the units of your answer at the end of the calculation.

As you come in, The Materials: –Paper, calculator, practice packet and pencil –Get a remote control The Plan: –Opening Activity: Go over Solubility Graphs –Assessment: Solubility Graph Quiz –Kinesthetic Activity: Preparing a Solution Lab –Individual Practice: Molarity & Molality Practice –15-2 Practice Problems WS 6, 8, 10-12, The Assessment: –Concentration (Molarity & Molality) Quiz – Friday (25pts) Musical Theme: Relaxing Wednesday

Preparing a Solution in the Lab You’ve learned about concentration (Molarity and molality). Therefore, you should be able to create your own solutions for use in the lab from now on. Example: 0.5 M HCl reacts with Mg(s) If I gave you HCl powder, what would you do to make the solution? Watch these kids, and assess your plan. Watch these kids Choose a lab group and station. Draw an assignment from the cup, and make the solution. Write your steps (including materials) as you go. ALSO: Solve 15-2 Practice Problems WS 6, 8, 10-12,

As you come in, The Materials: –Paper, calculator, practice packet and pencil The Plan: –Opening Activity: Molarity/molality Practice –Visual/Auditory Activity: Dilutions and Stoichiometry –Individual Practice: Solutions Stoichiometry in practice packet The Assessment: –Concentration (Molarity & Molality) Quiz – Friday (25pts) Musical Theme: Disney Day

Diluting Solutions If you already have a solution molarity, but you want a different molarity: Example: Your lab asks you to use 250 mL of 0.25M HCl, but you only find a jug of 6M HCl in the stockroom. USE THIS EQUATION: M 1 V 1 = M 2 V 2

Example 15.8 (page 539) What volume of 16 M sulfuric acid must be used to prepare 1.5 L of a 0.10 M H 2 SO 4 solution? *Be sure to solve the Dilution Worksheet in your practice packet!

Using Molarity as a Conversion Factor You have learned to calculate molarity using the equation: Molarity = moles of solute / liter of solution Did you realize that the calculation is simply a ratio of solute to solution? Ratios (ie mole ratios, energy to mole ratios) can be used as conversion factors in stoichiometry. THEREFORE, molarity can be written into our dimensional analysis charts to solve stoichiometry problems.

Solutions Stoichiometry What volume of 1.5 M HCl is needed to react with 21.5 grams of NaOH? What is the molarity of a solution of H2S if 48.5mL are required to titrate 35.6mL of 0.35M Fe(OH)3 solution? A white precipitate forms when 200 mL of 0.200M K3PO4 solution is mixed with 300 mL of M CaCl2 solution. What mass of precipitate will form? BE SURE TO SOLVE THE PRACTICE PROBLEMS IN YOUR PACKET!

Diluting A Solution Lab Purpose: See group assignment Materials: What else would you need? Safety: What should you think about? Procedure: Part One: Making the solution from “scratch”. Part Two: Dilution. Write it out step by step! Results & Conclusions: How do you need to revise your procedure? MUST HAVE NOTEBOOK APPROVED BEFORE MOVING TO STATION

As you come in, The Materials: Remote control, paper, pencil, calculator, practice packet The Plan: Opening Activity: Concentration Quiz Self-Assessment Activity: Go over Stoichiometry Exit Question Visual/Auditory Activity: Colligative Properties notes Individual Practice: Solving 15-4 colligative properties calculations in packet The Assessment: Colligative Properties Quiz (15 pts) - Tuesday Musical Theme: Greatest Hits Friday

Physical properties of solution are different from the physical properties of the solvent. Some properties are different simply because there are “foreign” particles (solute) in the solvent. Colligative properties of solutions depend only on the number of solute particles.

Number of Particles of Solute Think back to what you’ve learned about ionic and covalent compounds dissolving in water. Ionic compounds DISSOCIATE as they dissolve. Covalent compounds do NOT dissociate as they dissolve. Apply this idea. How many solute particles will 1 “piece” of NaCl add to a solvent? Answer: 2 (Na+ and Cl-)

Applying the Concept Further How many solute particles will 1 piece of magnesium phosphate add to a solvent? Mg 3 (PO 4 ) 2 breaks into 3 Mg 2+ ions and 2 PO 4 3- ions. Answer: 5 solute particles How many solute particles will 1 piece of sugar add to a solvent? Sugar is covalent. Answer: 1 solute particle Finally, which of the two above will affect a colligative property the most?

Boiling point is changed when solute is added to the solvent. Boiling point elevates when a solute is added to a solvent. The solution requires more energy to reach boiling. Example: Salt water will not boil at 100°C. It will boil at a HIGHER temp.

As you come in, The Materials: –Paper and pencil The Plan: –Visual/Auditory Activity: Review colligative properties –Collaborative Partners: Colligative properties practice The Assessment: –Colligative Properties Quiz: Tuesday –Cumulative Quiz: Thursday –Unit Test: Friday Musical Theme: Motown Monday

Calculating the NEW Boiling Pt. ∆T b = K b m i ∆T b = change in boiling pt. K b = boiling point constant for the solvent (will be given) m = molality i = number of ions present in the solute (USE ONLY WITH IONIC SOLUTES!)

Example of Boiling Pt. Calculation What is the boiling point when 15.0g NaCl is dissolved into 200 mL of water? (K b of water is 0.52 °C/m) ∆T b = K b m i You are solving for ∆T b, and you have the K b to use. m =You’ll need to calculate the molality from the info in the question. (change 15.0 g of NaCl to moles and 200 mL to kg and plug in) i = Finally, is the solute ionic? YES…NaCl is ionic and will give TWO ions when dissolved.

CHALLENGING: How many grams of NaCl would need to be added to the water to change the boiling temperature of 200 mL to 110°C? K b of water = 0.52°C/m 10C = m(0.52)(2) m = m = mole/0.2kg mole = 1.92 mole NaCl grams NaCl

Freezing point is changed when solute is added to the solvent. Freezing point depresses when a solute is added to a solvent. The solution requires a lower temp to reach freezing. Example: Salt water will not freeze at 0°C. It will freeze at a LOWER temp.

Calculating a NEW Freezing Pt. ∆T f = K f m i ∆T f = change in freezing pt. K f = freezing point constant for the solvent (will be given) m = molality i = number of ions present in solute (USE ONLY WITH IONIC SOLUTES)

Example of Freezing Pt. Calculation What is the freezing point when 15.0g NaCl is dissolved into 200 mL of water? (K f of water is 1.86 °C/m) ∆T f = K f m i You are solving for ∆T f, and you have the K f to use. m =You’ll need to calculate the molality from the info in the question. (change 15.0 g of NaCl to moles and 200 mL to kg and plug in) i = Finally, is the solute ionic? YES…NaCl is ionic and will give TWO ions when dissolved.

CHALLENGING: How many grams of NaCl would need to be added to the water to change the freezing temperature of 200 mL to -8°C? K f of water = 1.86°C/m 8C = m(1.86C/m)(2) molality = = mole/0.2kg mole = 0.43 mole NaCl grams NaCl

Practice Practice Practice! The 15-4 Practice Problems in your practice packet are boiling point/freezing point calculations. The key is posted at the front of the classroom. Colligative Properties Quiz - Tuesday PLEASE SOLVE MANY OF THESE PROBLEMS! You’ll see several on Friday’s test.

As you come in, The Materials: Paper, pencil, calculator, practice packet The Plan: Opening Activity: “We Solute You”We Solute You Collaborative Practice: Solving “Colligative properties problems” in packet Pre-Lab Activity: Prepare for Ice Cream Lab The Assessment: Colligative Properties Quiz (15 pts) - Tuesday Musical Theme: Motown Monday

About.comChemistry Ice has to absorb energy in order to melt, changing the phase of water from a solid to a liquid. When you use ice to cool the ingredients for ice cream, the energy is absorbed from the ingredients and from the outside environment (like your hands, if you are holding the baggie of ice!). When you add salt to the ice, it lowers the freezing point of the ice, so even more energy has to be absorbed from the environment in order for the ice to melt. This makes the ice colder than it was before, which is how your ice cream freezes. Ideally, you would make your ice cream using 'ice cream salt', which is just salt sold as large crystals instead of the small crystals you see in table salt. The larger crystals take more time to dissolve in the water around the ice, which allows for even cooling of the ice cream.