SOLUTION Definition:

 Homogeneous mixture of 2 or more substances  Ex. salt water, tea

 Homogeneous – Can’t distinguish parts of solution.

 All in 1 phase PARTS OF A SOLUTION  Solute - Substance being  Water is the universal dissolved solvent.  Salt

 Solvent - Dissolving medium  Liquid solutions are  Water – aqueous solution clear!  Isopropyl alcohol

SOLUTIONS CAN EXIST IN ALL PHASES:

 Air – Gaseous solution

 Alloy – Solid solution (Brass = Cu + Zn)

 Most solutions are liquids

 In all gas or all liquid solutions, the smaller amount is the solute!

 Seawater is a solution SOLUBILITY TERMS:  Soluble – Substance  Miscible – 2 liquids dissolves in another soluble in each other substance  Alcohol & water  Sugar in water  Immiscible – 2 liquids are insoluble

 Oil & water – form layers

 Insoluble – Does not dissolve in substance  Sand in water

SOLVATION IN AQUEOUS SOLUTIONS

 Solvation – Solvent particles surround solute to form a solution.  Hydration – Solvation with water

“LIKES DISSOLVE LIKES” • Polar substances dissolve  Predict which will in polar substances dissolve in each other:

• water & alcohol or  water (polar) ionic substances (NaCl)  octane (nonpolar)  sugar (polar) • Nonpolar substances  NaF (ionic) dissolve in nonpolar  benzene (nonpolar) substances oil & gasoline  Sugar and NaF are soluble in water

 Octane & benzene are soluble

FACTORS THAT INCREASE SOLVATION:

1) Stirring

2) Increase surface area (crush)

3) Increase temperature of solvent

HEAT OF SOLUTION Exothermic  Releases heat - gets warm  NaOH + water

Endothermic  Absorbs heat – gets cool  Cool  ← Ammonium nitrate

SOLUBILITY – Maximum amount solute that will dissolve in given amount of solvent at a certain temperature

 Saturated – Solution contains maximum amount of dissolved solute for given amount solvent (given temp. & pressure)

 Unsaturated – Contains less Solute than the solvent can hold (Can dissolve more solute)

 Saturated solution:  (Additional solute falls to bottom)

SATURATED SOLUTIONS ARE IN EQUILIBRIUM SUPERSATURATED SOLUTIONS:  Contains more dissolved  Ex. Sweet tea – Made by solute than a saturated heating water, adding solution at the same more solute, then cooling temperature down.

 Unstable  May recrystallize if disturbed

FACTORS AFFECTING SOLUBILITY: Temperature  Solubility of a solid - Increases when temperature increases -Sugar & water

 Solubility of a gas – Decreases when temperature increases - Oxygen & water SOLUBILITY CURVE – Shows saturated solutions

1) How much KCl (potassium chloride) will dissolve in 100 g water at 90°C?  54 g KCl

2) At what temperature

will 10 g of KClO3 (potassium chlorate) dissolve in 100 g water?  30°C

SOLUBILITY CURVE Saturated, Unsaturated or Supersaturated?

3) If 50 g KCl is dissolved in 100 g water at 90°C, describe the solution.

 How much additional KCl was added?

4) If 70 g CaCl2 is dissolved in 100 g water at 10°C, describe the solution.

 How much extra CaCl2 was added?

SOLUBILITY CURVE FOR OXYGEN  What happens to  Suppose a company dumps

solubility of O2 as warm, clean water in a lake. temperature rises?  What might happen to the

fish? Solubility Curve for Oxygen Gas in Water

15  Explain how this might

10 Series1 affect the food chain. 5

in 1000g of water 0 mg of oxygen dissolved 0 10 20 30 40 50 Temperature (degrees Celsius) PRESSURE & SOLUBILITY (Gases only)  Henry’s Law – Solubility  Ex. Soft drink – bubbles directly proportional to when open pressure

 S = S 1 2 P1 P2

 Pressure does not affect solubility of solids &  liquids. CO2 most soluble when drink is cold & at high pressure – unopened.

HENRY’S LAW If 0.85g of gas at 4.0 atm pressure dissolves in 1.0L water at 25ºC, how much will dissolve at 1.0 atm and at the same temperature?  0.85g/L = S  S1 = S2 2 4.0atm 1.0atm P1 P2

 S = 0.85 g/L 1  (0.85g/L)(1.0)=(S2)(4.0)  S2 = ? g/L  P = 4.0 atm 1  S2 = (0.85g/L)(1.0)  P2 = 1.0 atm (4.0)

 S2 = 0.21 g/L

HENRY’S LAW

2 L bottle 2 L bottle after opening before opening and pouring and pouring What factors (T&P) would increase solubility of sugar & carbon dioxide when making a soft drink?

 To dissolve more sugar (solid), increase temperature

 To dissolve more CO2 (g), decrease temperature, increase pressure

SOLUTE VS. SOLVENT

 Water is the universal solvent SOLUTION CONCENTRATION: The amount of solute dissolved in a specific amount of solvent or solution.

 Concentrated – contains large amount solute

 Dilute – contains small amount solute

MOLARITY (MOLAR CONCENTRATION) 2) MOLARITY (M) – Number moles of solute dissolved per liter of solution.  Molarity (M) = moles solute(n) liters solution

 To make 1 Molar solution of NaCl  Dissolve 1 mole (58.55 g) of NaCl in water to the line of a 1 liter volumetric flask

 1 mole NaCl = 23.00 + 35.45 = 58.55 g PROBLEM: Find molar concentration (molarity) of 100. mL of a solution containing 0.075 mol of dissolved NaCl.  M = # moles solute  M = 0.075 mol liters solution 0.100 L

 #moles = 0.075 mol  M = 0.75 mol/L

 #L = 100.mL x 1 L = 0.100 L = 0.75 M 1000 mL

PROBLEM: Calculate the molarity of 500. mL of a solution containing 0.400 moles HCl. M = # moles(n) volume (L) n = 0.400 mol volume = 500.mL x 1 L 1000 mL = 0.500 L

M = 0.400 mol = 0.800 mol/L 0.500 L

= 0.800 M

PROBLEM: What is the mass (g) of sodium hydroxide, NaOH in 2.00 L of a 0.25 M solution?  To find mass, multiply moles by M = # moles molar mass!

liters 0.50 mol NaOH x 40.00 g

1 mol # moles = M x liters = 20.0 g NaOH # mol = 0.25 mol x 2.00 L L

= 0.50 mol NaOH

Molality

 Molality (m): # of moles dissolved in each kilogram of solvent

m = moles of solute kg of solvent

 Independent of temp

Calculate the molality of a sol’n prepared by dissolving 20.4 g of sodium chloride in 192g of water.

 m = moles of solute kg of solvent

1. Convert 20.4 grams of NaCl to moles 2. Convert 192 g to kg 3. Divide moles by kg What is the molality of a solid solution containing 0.125g of chromium and 81.3g of iron?

 m = moles of solute kg of solvent .125 g Cr x 1 mole = .00240 moles Cr 52.00 g 81.3 g Fe x 1 kg = .0813 kg Fe 1000 g m = .00240 moles = .0295 m .0814 kg

EXPRESS CONCENTRATION AS MOLE FRACTION Mole fraction (X): # of moles of one component divided by the total # of moles in the solution X = moles of component total moles of sol’n  Used to compare solute and solvent  Solute + Solvent = Whole Solution What are the mole fractions of ethyl alcohol (C2H5OH) and water in a solution prepared by adding 50.0g of ethyl alcohol to 50.0g of water?  50.0 g ethanol x 1 mole = 1.09 moles ethanol 46.08 g  50.0 g water x 1 mole = 2.77 moles water 18.02 g  Total moles = 1.09 + 2.77 = 3.86 moles

 Mole Fraction = 1.09 moles ethanol = .282 3.86 moles  Mole Fraction = 2.77 moles water = .718 3.86 moles

DILUTING SOLUTIONS

M1V1 = M2V2  What volume (mL) of concentrated (12.0 M) hydrochloric acid (HCl) solution must be used to make 0.500 L of a 3.00 M HCl solution?

M1V1 = initial (stock) M2V2 = final solution

12.0M x V1 = 3.00 M x 0.500 L

V1 = 3.00 x 0.500 L 12.0

= 0.125 L

= 125mL

COLLIGATIVE PROPERTIES  Physical properties of  Vapor Pressure Lowering solutions that are affected by the number (not identity) of dissolved solute  Boiling Point Elevation particles

 Freezing Point Depression

 Osmotic Pressure ELECTROLYTES - Have greater effect on colligative properties - produce more particles.  Electrolytes – Form ions in solution (ionic, acids) that conduct electricity

Ex. NaCl (s)  Na+(aq) + Cl-(aq) 1 mol 1 mol 1 mol

Note: 1 mole NaCl yields 2 moles of ions

Acids (Start with H) HCl(g)  H+(aq) + Cl-(aq) 1 mol 1 mol 1 mol

Note: 1 mole HCl yields 2 moles of ions

Nonelectrolytes – Do not ionize (Don’t conduct - covalent)

 Ex. C6H12O6 (s)  C6H12O6 (aq)  1 mole 1 mole

 Note: 1 mol glucose yields 1 mol

 *NaCl & HCl have greater effect on colligative properties (1 mole yields 2 moles ions) Which would have the greatest effect on colligative properties?

1 molal: Sucrose (C12H22O11) Mg(NO3)2 AlBr3

 Sucrose (molecular): = 1 molecule

2+ -  Mg(NO3)2 forms 1 Mg and 2 NO3 = 3 ions

3+ -  AlBr3 forms Al and 3 Br = 4 ions

 AlBr3 has the greatest effect on colligative properties since most particles.

Sucrose VAPOR PRESSURE: Pressure exerted in closed container by particles entering gaseous state.

 Adding solute – Lowers solvent’s vapor pressure

 Fewer solvent particles are at the surface, so less solvent vaporizes. Result: Lower vapor pressure

VAPOR PRESSURE – LOWERED BY ADDING SOLUTE BOILING POINT ELEVATION  In order to boil, vapor pressure must equal the atmospheric pressure

 When solute is added, vapor pressure is lowered.

 Thus, solution must be heated to higher temperature.

 Result: Boiling point increases  Adding salt to water when cooking

Salt raises boiling point of water when cooking pasta: QUIZ 1. Colligative properties depend on the ___particles, not the type.

2. Which has the greatest effect on the colligative properties: KCl C12H22O11 CaCl2 NO2 HCl

3. Vapor pressure is caused by particles in a ___ container entering the gaseous state. Adding a solute ___the vapor pressure.

4. ____occurs when the vapor pressure equals the atmospheric pressure. Adding a solute will ____the boiling point. FREEZING POINT DEPRESSION  Adding solute lowers freezing point  Salt used on icy roads; making ice cream

 Solids – have a high attraction between particles.

 Adding a solute interferes with the attraction between these particles. OSMOTIC PRESSURE

 Osmosis – diffusion of solvent particles across a semipermeable membrane (from higher to lower concentration)

 Addition of solute causes water to move from the solvent (water) side to the solution side.

QUIZ 1) Adding a solute will ___ the freezing point. Give 2 practical applications of this.

2) a) Diffusion of solvent particles across a semi permeable membrane is called ____. Particles move from ______concentration to ______concentration.

b) Adding a solute causes water to move from the ____(water) side to the ____side of the membrane. QUIZ

1) A solution is a ___mixture of 2 or more ___. 2) Homogeneous means that you cannot distinguish the ___ and it is in one ___. 3) Name the solutes and solvent in sweet tea. 4) ___is the universal solvent. 5) An example of a gaseous solution is ___. 6) An alloy is a solution made of ___. Give an example of an alloy. 7) In aqueous solutions, ___ is the solvent.

SOLUTION QUIZ

1) A substance that dissolves in another is ___. 2) Sand and water are ___. 3) Two liquids that are soluble are called ____. 4) Oil and water are ____. 5) Solvation with water is called _____. 6) “Likes dissolve likes” means that polar substances dissolve ___ and ___. Oil and water are insoluble because water is __ and oil is __.

QUIZ 1) Name 3 things that will increase solvation. (Suppose you want to make Kool-Aid quickly). 2) When mixing calcium chloride and water, the solution gets warmer. This is ____. 3) A ___solution contains the maximum amount of solute at a given temperature (& pressure). 4) More solute can be added means the solution is___. 5) To make a supersaturated solution, ___ the solution, add more solute, then ___ it back down.

THE END What is the molality of a solid solution containing 0.125g of chromium and 81.3g of iron?

 m = moles of solute kg of solution .125 g Cr x 1 mole = .00240 moles Cr 52.00 g .125 g Cr x 1 kg = 1.25 x 10-4 kg Cr 1000 g 81.3 g Fe x 1 kg = .0813 kg Fe 1000 g Total kg = .0813 + 1.25 x 10-4 = .0814 kg  m = .00240 moles = .0295 m .0814 kg

Calculate the molality of a sol’n prepared by dissolving 20.4 g of sodium chloride in 192g of water.

 M = moles of solute kg of solution

1. Convert 20.4 grams of NaCl to moles 2. Convert 192 g to kg 3. Divide moles by kg