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

dissolved Salt

Solvent - Dissolving medium Water – aqueous solution Isopropyl alcohol

Water is the universal solvent.

Liquid solutions are clear!

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

dissolves in another substance

Sugar in water

Insoluble – Does not

dissolve in substance Sand in water

Miscible – 2 liquids soluble in each other

Alcohol & water

Immiscible – 2 liquids are insoluble

Oil & water – form layers

SOLVATION IN AQUEOUS SOLUTIONS

Solvation – Solvent particles surround solute to

form a solution.

Hydration – Solvation with water

“LIKES DISSOLVE LIKES”

Predict which will dissolve in each other:

water (polar)

octane (nonpolar)

sugar (polar)

NaF (ionic)

benzene (nonpolar)

Sugar and NaF are soluble in water

Octane & benzene are soluble

• Polar substances dissolve

in polar substances

• water & alcohol or

ionic substances (NaCl)

• Nonpolar substances

dissolve in nonpolar

substances

oil & gasoline

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

solute than a saturated solution at the same temperature

Unstable

May recrystallize if disturbed

Ex. Sweet tea – Made by heating water, adding more solute, then cooling down.

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

solubility of O2 as temperature rises?

Suppose a company dumps warm, clean water in a lake.

What might happen to the fish?

Explain how this might affect the food chain.

Solubility Curve for Oxygen Gas in Water

0

5

10

15

0 10 20 30 40 50

Temperature (degrees Celsius)

mg

of

oxy

ge

n d

iss

olv

ed

in 1

00

0g

of

wa

ter

Series1

PRESSURE & SOLUBILITY (Gases only)

Henry’s Law – Solubility directly proportional to pressure

S1 = S2 P1 P2

Pressure does not affect

solubility of solids & liquids.

Ex. Soft drink – bubbles when open

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?

S1 = S2

P1 P2

S1 = 0.85 g/L

S2 = ? g/L

P1 = 4.0 atm

P2 = 1.0 atm

0.85g/L = S2

4.0atm 1.0atm

(0.85g/L)(1.0)=(S2)(4.0)

S2 = (0.85g/L)(1.0)

(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

liters solution

#moles = 0.075 mol

#L = 100.mL x 1 L = 0.100 L

1000 mL

M = 0.075 mol 0.100 L

M = 0.75 mol/L

= 0.75 M

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?

M = # moles

liters

# moles = M x liters

# mol = 0.25 mol x 2.00 L

L

= 0.50 mol NaOH

To find mass, multiply moles by molar mass!

0.50 mol NaOH x 40.00 g

1 mol

= 20.0 g NaOH

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

m = moles of solute

kg of solvent

Independent of temp

Molality

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

Vapor Pressure Lowering

Boiling Point Elevation

Freezing Point Depression

Osmotic Pressure

Physical properties of solutions that are affected by the number (not identity) of dissolved solute particles

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

Mg(NO3)2 forms 1 Mg2+ and 2 NO3- = 3 ions

AlBr3 forms Al3+ 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