To understand the process of dissolving Objectives To understand the process of dissolving To learn why certain substances dissolve in water and to predict solubility To learn qualitative terms describing the concentration of a solution To understand the factors that affect the rate at which a solid dissolves   

What is a solution? Solution – homogeneous mixture Solvent – substance present in largest amount Solutes – other substances in the solution Aqueous solution – solution with water as the solvent

Solubility of Ionic Substances A. Solubility Solubility of Ionic Substances Ionic substances breakup into individual cations and anions. PHet Solubility

Solubility of Ionic Substances A. Solubility Solubility of Ionic Substances Polar water molecules interact with the positive and negative ions of a salt.

Solubility of Polar Substances A. Solubility Solubility of Polar Substances

Ethanol is soluble in water because of the polar OH bond. A. Solubility Ethanol is soluble in water because of the polar OH bond.

Why is solid sugar soluble in water? A. Solubility Solubility of Polar Substances Why is solid sugar soluble in water?

Substances Insoluble in Water Nonpolar oil does not interact with polar water. Water-water hydrogen bonds keep the water from mixing with the nonpolar molecules.

How Substances Dissolve A. Solubility How Substances Dissolve A “hole” must be made in the water structure for each solute particle. The lost water-water interactions must be replaced by water-solute interactions. “like dissolves like”

Predict if the following substances would dissolve in water…. A. Solubility Predict if the following substances would dissolve in water…. NH3 BCl3 CH4 CH3Cl H2S HCl

How Substances Dissolve “like dissolves like” Packing popcorn demo A. Solubility How Substances Dissolve “like dissolves like” Packing popcorn demo Phenolphthalein in water What makes a good waterproof material? Gum in your hair?

Predict if the following substances would dissolve in water or oil A. Solubility Predict if the following substances would dissolve in water or oil CH3OH CH2Cl2 BF3 CH4 CH3CH2CH2CH2OH CCl4 AsH3 A bear swimming off the coast of Alaska

Why does soap do such a great job of dissolving most solutes? A. Solubility Why does soap do such a great job of dissolving most solutes?

B. Solution Composition: An Introduction The solubility of a solute is limited. Saturated solution – contains as much solute as will dissolve at that temperature Unsaturated solution – has not reached the limit of solute that will dissolve

B. Solution Composition: An Introduction Supersaturated solution – occurs when a solution is saturated at an elevated temperature and then allowed to cool but all of the solid remains dissolved Contains more dissolved solid than a saturated solution at that temperature Unstable – adding a crystal causes precipitation VIDEO? Hand Warmers?

B. Solution Composition: An Introduction Solutions are mixtures. Amounts of substances can vary in different solutions. Specify the amounts of solvent and solutes Qualitative measures of concentration concentrated – relatively large amount of solute dilute – relatively small amount of solute

B. Solution Composition: An Introduction Which solution is more concentrated?

B. Solution Composition: An Introduction Now which solution is more concentrated?

B. Solution Composition: An Introduction Now What units are used to express concentration? amount/volume mol/L g/L mg/L

C. Factors Affecting the Rate of Dissolving Surface area (molecular exposure) (grind) Stirring (increases molecular interactions) Temperature (increases speed of molecule) How will an increase in any of the above 3 factors affect the rate of dissolving? Why?

To understand the process of dissolving Objectives Review To understand the process of dissolving To learn why certain substances dissolve in water and to predict solubility To learn qualitative terms describing the concentration of a solution To understand the factors that affect the rate at which a solid dissolves   Work Session: Page 527 # 1, 3, 4, 6

To understand mass percent and how to calculate it Objectives To understand mass percent and how to calculate it To understand and use molarity To learn to calculate the concentration of a solution made by diluting a stock solution

A. Solution Composition: Mass Percent

A. Solution Composition: Mass Percent A solution is prepared by mixing 1.0 g of ethanol CH3CH2OH with 100.0 g of H2O. Calculate the mass percent of ethanol in this solution. mass % = mass solute X 100 mass solution mass % = ? mass solute = mass solution =

A. Solution Composition: Mass Percent A solution is prepared by mixing 1.0 g of ethanol CH3CH2OH with 100.0 g of H2O. Calculate the mass percent of ethanol in this solution. mass % = mass solute X 100 mass solution mass % = 1.0 g X 100 100.0 g + 1.0 g 0.990% ethanol

A. Solution Composition: Mass Percent If cow’s milk contains 4.5% by mass of lactose, C12H22O11, calculate the mass of lactose present in 175 g of milk. mass % = mass solute X 100 mass solution mass % = mass solute = mass solution =

A. Solution Composition: Mass Percent If cow’s milk contains 4.5% by mass of lactose, C12H22O11, calculate the mass of lactose present in 175 g of milk. mass % = mass solute X 100 mass solution mass % = 4.5% mass solute = ? mass solution = 175 g

A. Solution Composition: Mass Percent If cow’s milk contains 4.5% by mass of lactose, C12H22O11, calculate the mass of lactose present in 175 g of milk. mass solute= ? mass solute = mass% (mass solution ) 100 mass solute = 4.5% (175 g) 7.9 g lactose

B. Solution Composition: Molarity Concentration of a solution is the amount of solute in a given volume of solution.

B. Solution Composition: Molarity Consider both the amount of solute and the volume to find concentration.

B. Solution Composition: Molarity To find the moles of solute in a given volume of solution of known Molarity use the definition of Molarity. Molarity = moles of solute liters of sol’n Solve for moles of solute? moles of solute = (Molarity)(liters of sol’n) Deriving new formulas!!

B. Solution Composition: Molarity Calculate the Molarity of a solution prepared by dissolving 11.5 g of solid NaOH in enough water to make 1.5 L solution. Molarity = M = moles of solute L of solution M = Moles solute = L of solution =

B. Solution Composition: Molarity Calculate the Molarity of a solution prepared by dissolving 11.5 g of solid NaOH in enough water to make 1.5 L solution. Molarity = M = moles of solute L of solution M = ? Moles solute = 11.5 g = L of solution = 1.5 L M = (0.288 mol)/(1.5 L) = 0.192 M

B. Solution Composition: Molarity Calculate the Molarity of a solution prepared by dissolving 1.56 g of gaseous HCl in enough water to make 26.8 mL solution. Molarity = M = moles of solute L of solution M = Moles solute = L of solution =

B. Solution Composition: Molarity Calculate the Molarity of a solution prepared by dissolving 1.56 g of gaseous HCl in enough water to make 26.8 mL solution. Molarity = M = moles of solute L of solution M = ? Moles solute = 1.56 g = L of solution = 26.8 mL =

B. Solution Composition: Molarity Calculate the Molarity of a solution prepared by dissolving 1.56 g of gaseous HCl in enough water to make 26.8 mL solution. Molarity = M = moles of solute L of solution M = ? Moles solute = 0.0427 mol L of solution = 0.0268 L M = (0.0427 mol)/(0.0268 L) = 1.59 M HCl

B. Solution Composition: Molarity To analyze the alcohol content, a chemist needs 1.0 L of 0.20 M K2Cr2O7 solution. What mass of K2Cr2O7 is needed? M = moles of solute L of solution M = solve for ? Moles solute = L of solution =

B. Solution Composition: Molarity To analyze the alcohol content, a chemist needs 1.0 L of 0.20 M K2Cr2O7 solution. What mass of K2Cr2O7 is needed? M = moles of solute L of solution M = 0.20 M moles solute = ? L of solution = 1.0 L moles of solute = M(L of solution)

B. Solution Composition: Molarity To analyze the alcohol content, a chemist needs 1.0 L of 0.20 M K2Cr2O7 solution. What mass of K2Cr2O7 is needed? moles of solute = M(L of solution) moles of solute = (0.20 M) (1.0 L) moles of solute = 0.2 mol Need g?? 0.2 mol K2Cr2O7 = g 294.2 g/mol  58.8 g K2Cr2O7

B. Solution Composition: Molarity Standard solution - a solution whose concentration is accurately known To make a standard solution Mass out a sample of solute. Transfer to a volumetric flask. Add enough solvent to mark on flask. Spinner plate, magnetic pill, wand…….

B. Solution Composition: Molarity (Glassmaking)

C. Dilution Water can be added to an aqueous solution to dilute the solution to a lower concentration. Only water is added in the dilution – the amount of solute is the same in both the original and final solution.

D. Dilution Diluting a solution Mix a measured amount of original solution with DI water in a volumetric flask Use the formula M1V1 = M2V2 M = Molarity V = Volume

D. Dilution

D. Dilution How much water must be added to 1.0 L of 8.0 M HCl to dilute it to a 5 M solution? M1V1 = M2V2 M1= V1 = M2= V2 = V2 = 1.6 L

D. Dilution What volume of 16 M NaOH must be used to prepare 1.5 L of a 0.10 M NaOH solution? M1V1 = M2V2 M1= V1 = M2= V2 = V2 = 9.4 X 10-3 L = mL 9.4 mL

To understand mass percent and how to calculate it Objectives Review To understand mass percent and how to calculate it To understand and use molarity To learn to calculate the concentration of a solution made by diluting a stock solution Why ask a chemist for advice? Work Session: Review 15.2 page 540 #1, 4, 5, 6, 7: Pg 528 Practice Prob 15.1, Pg 530 PP 15.2, Pg 532 PP 15.4, Pg 535 PP 15.7, Pg 539 PP 15.8

To understand the effect of a solute on solution properties Objectives To understand the effect of a solute on solution properties   

Objectives To   

D. Boiling Point and Freezing Point The presence of solute “particles” causes the liquid range to become wider. Boiling point increases (add a pinch of salt when you boil water for spaghetti) Freezing point decreases (add rock salt when you make ice-cream) Salting the Interstate in winter

D. Boiling Point and Freezing Point Why does the boiling point increase? Forming a bubble in a solution

D. Boiling Point and Freezing Point Solute particles block some of the water molecules trying to enter the bubble. Need higher pressure to maintain the bubble because of fewer particles colliding

D. Boiling Point and Freezing Point Colligative property – a solution property that depends on the number of solute particles present Boiling Point Elevation Freezing Point Depression

To understand the effect of a solute on solution properties Objectives Review To understand the effect of a solute on solution properties Work Session: Review Page 553 #8 Page 557 # 49, 51   

This is the end of the required material for this chapter. Objectives Review This is the end of the required material for this chapter.  

To learn to solve stoichiometric problems involving solution reactions Objectives Review To learn to solve stoichiometric problems involving solution reactions To do calculations involving acid-base reactions To learn about normality and equivalent weight To use normality in stoichiometric calculations To understand the effect of a solute on solution properties   

A. Stoichiometry of Solution Reactions

B. Neutralization Reactions An acid-base reaction is called a neutralization reaction. Steps to solve these problems are the same as before.

C. Normality Unit of concentration One equivalent of acid – amount of acid that furnishes 1 mol of H+ ions One equivalent of base – amount of base that furnishes 1 mol of OH ions Equivalent weight – mass in grams of 1 equivalent of acid or base

C. Normality

C. Normality

C. Normality To find number of equivalents

C. Normality Advantage of equivalents