Chapter 14 Mixtures and Solutions. 14.1 Types of Mixtures What is a Mixture? What is a Mixture? –A combination of 2 or more kinds of matter, each retains

Chapter 14Chapter 14

Mixtures and SolutionsMixtures and Solutions

14.1 Types of Mixtures14.1 Types of Mixtures

What is a Mixture?What is a Mixture?– A combination of A combination of 2 or more 2 or more kinds of kinds of

matter, each retains its own matter, each retains its own composition and propertiescomposition and properties..

– HomogeneousHomogeneous: a mixture : a mixture with with uniformuniform composition (ex: composition (ex: saltsalt water). water).

– HeterogeneousHeterogeneous: a mixture : a mixture without without uniformuniform composition (ex: composition (ex: dirtydirty water).water).

Types of MixturesTypes of Mixtures

Solutions Solutions – A homogeneous mixture in a single A homogeneous mixture in a single

phasephase..– Properties:Properties:

uniformuniform distribution of particles distribution of particles won’twon’t settle out settle out transparenttransparent can’t becan’t be filtered out (small particle size) filtered out (small particle size)

Types of MixturesTypes of Mixtures

The nature of solutions:The nature of solutions: SoluteSolute: the part that : the part that gets dissolvedgets dissolved.. SolventSolvent: the part that : the part that does the does the

dissolvingdissolving.. AqueousAqueous: (aq) a solution that contains : (aq) a solution that contains

waterwater as the solvent. as the solvent. TincturesTinctures: solutions that contains : solutions that contains

alcoholalcohol as the solvent as the solvent – Examples: IExamples: I22 in alcohol, phenolphthalein in alcohol, phenolphthalein

solutionssolutions

SolutionsSolutions

Solutions can be electrolytes or Solutions can be electrolytes or non-electrolytes.non-electrolytes.– What is an electrolyte?What is an electrolyte?

Salts. Anything that dissolves in water and Salts. Anything that dissolves in water and conducts electricity.conducts electricity.

Solutes are classified according to whether Solutes are classified according to whether they dissolve to form neutral molecules or they dissolve to form neutral molecules or charged ions.charged ions. Salts Dissolve to Form

Molecules

(Non-electrolytes

Ions

Electrolytes

SolutionsSolutions

3 Types of solutions3 Types of solutions– Gaseous solutionsGaseous solutions - air - air– Liquid solutionsLiquid solutions – vinegar (acetic acid – vinegar (acetic acid

dissolved in water); soft drinks dissolved in water); soft drinks (solutions of a gas, CO(solutions of a gas, CO22, dissolved in , dissolved in water.water.

– Solid solutionsSolid solutions – alloys such as – alloys such as sterling silver – 92% silver, 8% sterling silver – 92% silver, 8% copper; white gold – gold containing copper; white gold – gold containing nickel, tin, zinc or copper.nickel, tin, zinc or copper.

SuspensionsSuspensions

A heterogeneous mixture of A heterogeneous mixture of the the largest particles that settle outlargest particles that settle out..– Example – a jar of muddy water, Example – a jar of muddy water,

Italian dressingItalian dressing

ColloidsColloids

Colloids contain intermediate size Colloids contain intermediate size particles that remain in suspension particles that remain in suspension because because they are too small to settle outthey are too small to settle out..– Example – the large particles settle out of the Example – the large particles settle out of the

muddy water, but the water remains cloudy. muddy water, but the water remains cloudy. The cloudy water cannot be filtered because The cloudy water cannot be filtered because the particles are too small and remain in the particles are too small and remain in suspension due to the constant movement of suspension due to the constant movement of the liquid molecules.the liquid molecules.

– Colloids include – mayonnaise (solid Colloids include – mayonnaise (solid emulsion), foam, smoke (solid dispersed in emulsion), foam, smoke (solid dispersed in gas), fog (liquid dispersed in gas) gas), fog (liquid dispersed in gas)

Colloid or Solutions?Colloid or Solutions?

Classify as either a solution or colloid

Rubbing alcohol _______ Milk _______

Medicine _________ Vinegar _________

H2O2 _______ Windex _______

Gasoline _______ Mayonnaise _______

Hairspray _______ Jello _______

Scope _______ 7-up _______________

Toothpaste _______

CS

C

C

SS

S

S

Classification of MatterClassification of Matter

Matter

Pure Substances Mixtures

Elements Compounds Homogeneous Heterogeneous

Solutions Colloids Suspensions

Fill in the flow chart with the following words: Mixtures, Matter, Pure Substances, Homogeneous, Heterogeneous, elements, compounds,

suspensions, colloids, solutions

14.2 The solution 14.2 The solution process process Factors affecting the rate of dissolving Degree of Solubility: the amount of

substance required to form a saturated solution in a certain amount of solvent at a certain temperature.– solute + solvent ↔ solution

(equilibrium)

Factors affecting the rate of dissolving

If you wish to dissolve a substance, you can help by:– crush it (increase surface area)– stir it– heat it

Factors affecting Factors affecting solubilitysolubility 1. Types of solvents and 1. Types of solvents and

solutes –“Like dissolves like”solutes –“Like dissolves like”

Polar/ionicPolar/ionic vs. vs. nonpolarnonpolar waterwater oil oil saltsalt gasolinegasoline sugarsugar Styrofoam Styrofoam

““Like dissolves Like”Like dissolves Like”

Ionic substances dissolve in polar substances – salt dissolves in water

Non polar substances dissolve in non polar substances – fats, oils, gasoline dissolve

Immiscible substances do not dissolve in each other (salad dressing – oil and vinegar)

Miscible substances do dissolve in each other (gasoline and benzene)

Factors affecting Factors affecting solubilitysolubility 2. Pressure (gases only)

– As pressure increase, solubility increases.

– Henry’s law: solubility is proportional to pressure.

– Effervescence: the escape of a gas from a solution (a carbonated soft drink effervesces when the bottle is opened and the pressure is reduced)

S

P

Factors affecting Factors affecting solubilitysolubility 3. Temperature

– For most solids, solubility increases as temperature increases

– For gases, solubility decreases as temperature increases

S

T

S

T

Heats of SolutionHeats of Solution

Solubility, the nature of solute and solvent, and the energy changes during solution formation

Dissolving an ionic compound in water

NaNa

NaNa Cl

Cl

ClCl O-2

O-2H+

H+

H+

H+

O-2

H+

H+ O-2

H+

H+

Na+

Na+

Cl- Cl-

Cl- Cl- Step #1 Step #2 Step #3 Breakup the Breakup the Formation of

Formation of the solvent the solution Solute (endothermic) (endothermic) (exothermic)


If step #1 plus step #2 are more than step If step #1 plus step #2 are more than step #3, then the overall reaction is #3, then the overall reaction is endothermicendothermic..

Energy Level DiagramEnergy Level Diagram

E

Time

1

2 3


If step #1 plus step #2 are less than step #3, If step #1 plus step #2 are less than step #3, then the overall reaction is then the overall reaction is exothermicexothermic..

Energy Level DiagramEnergy Level Diagram

E2 3

1

Time

Heat of Heat of Solution/HydrationSolution/Hydration Heat of Solution: The amount of heat absorbed or released

when a solute dissolves in a solvent.

Heat of Hydration: energy released when ions are surrounded by water molecules.– The # of water molecules used depends on the size and charge

of the ion.– ↑ Heat released (more negative) as the size of the ion ↓

Li+1 -523 kJ/mole vs Na+1 -418 kJ/mole– ↑ Heat released (more negative) as the charge of the ion ↑

Na+1 -418 kJ/mole vs Mg+2 -1949 kJ/mole

Li and Mg are close to the same size, so... charge means more

Heat of Heat of Solution/HydrationSolution/Hydration DissociationDissociation - separation of - separation of ions;ions;

caused by the action of the caused by the action of the solventsolvent.. HydrationHydration - the process of - the process of solutesolute

particles being surrounded by particles being surrounded by waterwater..

– Remember: polar/ionic dissolves polar/ionic (like dissolves like). O2 and CO2 are nonpolar. They don’t dissolve very much in water (just enough for sodas)

Solubility Curves and Solubility Curves and TablesTables Solubility Rules:Solubility Rules:

– solublesoluble (definition): more than 1 g of (definition): more than 1 g of solute dissolves per 100 g of watersolute dissolves per 100 g of water

– slightlyslightly solublesoluble: between 0.1 and 1 g : between 0.1 and 1 g dissolvesdissolves

– insolubleinsoluble: less than 0.1 g dissolves: less than 0.1 g dissolves

d = d = decomposesni - not isolated - not been found to

form

Saturated, unsaturated, Saturated, unsaturated, and supersaturated and supersaturated solutionssolutions Saturated SolutionSaturated Solution: :

– Holds as much solute as it can at a given temperature and certain amount of solvent.

– Temperature must be stated when determining solubility.

– For gases, pressure must also be stated when determining solubility.

Saturated, unsaturated, Saturated, unsaturated, and supersaturated and supersaturated solutionssolutions Unsaturated Solution

– The solution is currently dissolving less than the maximum amount of solute at a given temperature.

Supersaturated Solution– The solution currently holds more than

the maximum amount of solute at a given temperature.

How is this possible? These solutions are created by saturating a hot solution and allowing it to cool undisturbed.

Solubility ProblemsSolubility Problems

Ex1: What is the solubility of Ex1: What is the solubility of potassium chlorate at 50.0 potassium chlorate at 50.0 ooC in 100.0 C in 100.0 ml of water?ml of water?

Ex2: What temperature will result in a Ex2: What temperature will result in a saturated solution of 80.0 grams of saturated solution of 80.0 grams of sodium nitrate and 100.0 grams of sodium nitrate and 100.0 grams of water?water?

20.0 g of potassium chlorate in 100.0 grams of water

10.0 oC


Ex3: If 40.0 grams of ammonium chloride are placed in 100.0 grams of water at 50.0 oC, is the solution saturated or unsaturated? If saturated, how much salt remains undissolved? If unsaturated, how much more salt can be dissolved?

Ex4: If 80.0 grams of potassium nitrate are placed in 100.0 grams of water at 44.0°C, is the solution saturated or unsaturated? If saturated, how much salt remains undissolved? If unsaturated, how much more salt can be dissolved?

The solution is unsaturated and can hold 10.0 more grams of ammonium chloride.

The solution is saturated with 5.0 grams of potassium nitrate undissolved


Ex5: What is the solubility of sodium chloride at 90.0 oC in 50.0 ml of water?– At this temperature the 100.0 ml of water

can hold 40.0 grams of this salt. So, if half as much water is present, half as much salt will dissolve.

40.0 g = x 100.0 ml 50.0 ml

x = 20.0 grams of sodium in 50.0 grams of water


Ex6: What is the solubility of Ex6: What is the solubility of potassium nitrate at 50.0 potassium nitrate at 50.0 ooC in 200.0 C in 200.0 ml of water?ml of water?

80.0 g 80.0 g = = x x 100.0 ml 100.0 ml 200.0 ml 200.0 ml

x = 160.0 grams of potassium nitrate in x = 160.0 grams of potassium nitrate in

200.0 grams of water200.0 grams of water


Ex7: What is the solubility of Ex7: What is the solubility of ammonium chloride at 90.0 ammonium chloride at 90.0 ooC C in 68.2 ml of water?in 68.2 ml of water?

770.0 g 0.0 g = = x x 100.0 ml 100.0 ml

68.2 ml68.2 ml x = 47.7 grams of ammonium x = 47.7 grams of ammonium

chloride in 68.2 grams of waterchloride in 68.2 grams of water

14.3 Concentrations of 14.3 Concentrations of solutions solutions Dilute vs. ConcentratedDilute vs. Concentrated

– DiluteDilute: a : a smallsmall amount of solute in a amount of solute in a largelarge amount of solvent. amount of solvent.

– ConcentratedConcentrated: a : a largelarge amount of amount of solute in a solute in a smallsmall amount of solvent. amount of solvent.

Do not confuse with saturated and Do not confuse with saturated and unsaturated. For example, “a saturated unsaturated. For example, “a saturated solution may be either dilute or solution may be either dilute or concentrated.”concentrated.”

% by Mass of a Solute in % by Mass of a Solute in SolutionSolution

Example: Suppose we have a solution Example: Suppose we have a solution that contains 50.0 ml of alcohol (solute) that contains 50.0 ml of alcohol (solute) and 50.0 ml of water (solvent). If the and 50.0 ml of water (solvent). If the density of the alcohol is 0.800 g/mL, density of the alcohol is 0.800 g/mL, calculate the following percent solutions.calculate the following percent solutions.

General Formula solute * 100 = % by mass

solution

Three ways to Three ways to calculate the % calculate the % solution: solution: #1#1 Volume of solute Volume of solute x 100 x 100

Total Volume of Total Volume of solutionsolution

(50.0 ml / 100.0 ml) x 100 = 50.0 (50.0 ml / 100.0 ml) x 100 = 50.0 %%

Three ways to Three ways to calculate the % calculate the % solution:solution:# 2 Weight of solute Weight of solute x 100 x 100

Total Volume of solutionTotal Volume of solution

D = M/D = M/ V V M = DV M = DV

M = (.800 g/ml)(50.0 ml) M = (.800 g/ml)(50.0 ml)

M = 40.0 g soluteM = 40.0 g solute

(40.0 g / 100.0 ml) 100 = 40.0 % (40.0 g / 100.0 ml) 100 = 40.0 %

Three ways to Three ways to calculate the % calculate the % solution:solution:#3#3 Weight of solute Weight of solute x 100 x 100 Weight of solutionWeight of solution

D = M/V D = M/V M = DV M = DV M = (.800 g/ml)(50.0 ml) M = (.800 g/ml)(50.0 ml) M = 40.0 g soluteM = 40.0 g solute

D = M/V D = M/V M = DV M = DV M = (1.00 g/ml)(50.0 ml) M = (1.00 g/ml)(50.0 ml)

M = 50.0 g solventM = 50.0 g solvent

(40.0 g / 90.0g) 100 = 44.0 %(40.0 g / 90.0g) 100 = 44.0 %

MolarityMolarity

A method used to calculate concentration.– Molarity (M) = moles solute

Liters of solution

– Note: If given grams, use the periodic table to find the number of moles

– When you talk about a solution with a label of 6 M HCl, we say, “ Six molar solution.”

MolarityMolarity

What is the Molarity of a solution What is the Molarity of a solution made by dissolving 20.0 g of made by dissolving 20.0 g of HH22SOSO44 to a volume of 400.0 ml? to a volume of 400.0 ml?

MolalityMolality

Another method used to calculate Another method used to calculate concentration.concentration.

molality (m) =molality (m) = moles solute moles solute kg of solventkg of solvent

– When you talk about a solution with When you talk about a solution with a label of 6 m HCl, we say, “ Six a label of 6 m HCl, we say, “ Six molal solution.”solution.”

MolalityMolality

What is the molality of a solution What is the molality of a solution made by dissolving 3.5 g of made by dissolving 3.5 g of Ca(OH)Ca(OH)2 2 in 350 g of water? in 350 g of water?

DilutionsDilutions

CoVo CoVo = CnVn= CnVn

Ex. How many mL of water would Ex. How many mL of water would you need to add to 6.0 M Hyou need to add to 6.0 M H22SOSO44 so you could make 2.00 L of a so you could make 2.00 L of a 2.50 M solution? 2.50 M solution?

Documents

Chapter 14 Mixtures and Solutions. 14.1 Types of Mixtures What is a Mixture? What is a Mixture? –A combination of 2 or more kinds of matter, each retains