SOLUTIONSSOLUTIONS

Solution Solution – – homogeneous mixture homogeneous mixture made up of very small particles; made up of very small particles; the size of individual molecules, the size of individual molecules, atoms, or ionsatoms, or ions

Parts of a solutionParts of a solution

1.1. solute- solute- the substance that is the substance that is considered to be the dissolved considered to be the dissolved substancesubstance

2. solvent – the substance in 2. solvent – the substance in which the solute dissolveswhich the solute dissolves

Aqueous solution (aq) water is the solventAqueous solution (aq) water is the solvent

Tincture alcohol is the solventTincture alcohol is the solvent

““like dissolves like” meaning thatlike dissolves like” meaning that substances that contain similar substances that contain similar bond types will dissolve in each bond types will dissolve in each other.other.

Polar solvents will dissolve polar Polar solvents will dissolve polar and ionic substances (molecule to and ionic substances (molecule to ion attraction) but will not dissolve ion attraction) but will not dissolve non polar substances (oil and water)non polar substances (oil and water)

Typical properties:Typical properties:

1)solutions are 1)solutions are homogeneous homogeneous mixtures (aq)mixtures (aq)

2)2)dissolved particles will not dissolved particles will not come out ofcome out of solutionsolution no matter no matter how long it stands as long as it is how long it stands as long as it is covered to prevent evaporationcovered to prevent evaporation

3) 3) Clear and transparentClear and transparent-- dissolved dissolved particles are too small to see. It will particles are too small to see. It will not disperse lightnot disperse light

4) Because of extremely small particle 4) Because of extremely small particle size size the solution will pass the solution will pass through the finest filters and through the finest filters and leave no residueleave no residue

5)5)A solution is considered to be a A solution is considered to be a single phasesingle phase even though the even though the components may be of different components may be of different phases before the mixture was phases before the mixture was formedformed

Types of solutionsTypes of solutions

1)gas solutions- 1)gas solutions- gases or vapors gases or vapors dissolve in one another dissolve in one another

Example: AirExample: Air

2)liquid solutions- 2)liquid solutions- liquid solvent in liquid solvent in which a gas, liquid or solid is which a gas, liquid or solid is dissolveddissolved

Ex: sugar water , carbonated Ex: sugar water , carbonated beverages, antifreeze (ethylene glycol beverages, antifreeze (ethylene glycol in water)in water)

a. a. Miscible- two liquids that dissolve Miscible- two liquids that dissolve in one another-in one another- must have similar must have similar bondingbonding

b. Immiscibleb. Immiscible- two liquids that do not - two liquids that do not dissolve in one another.dissolve in one another. Like oil and Like oil and water must have dissimilar bondingwater must have dissimilar bonding

3)Solid solutions – 3)Solid solutions – mixture of solids mixture of solids uniformly spread throughout each uniformly spread throughout each other at the atomic or molecular other at the atomic or molecular level.level.

EX: alloy –2 or more metals - brass is EX: alloy –2 or more metals - brass is copper and zinccopper and zinc

Amalgam-alloy when one of the Amalgam-alloy when one of the metals is Hg- fillings are a Ag-Hg metals is Hg- fillings are a Ag-Hg amalgamamalgam

Solubility- Solubility- maximum amount of solute maximum amount of solute that can dissolve in a certain quantity that can dissolve in a certain quantity of a solvent at a certain temperature of a solvent at a certain temperature

Factors affecting solubilityFactors affecting solubility

1. Nature of the solute and solvent1. Nature of the solute and solvent

Example: 1 g of PbClExample: 1 g of PbCl22 dissolves in 100g of dissolves in 100g of water at room temp water at room temp

200g of ZnCl200g of ZnCl22 dissolves in 100 g of water dissolves in 100 g of water at room tempat room temp

2.2. Temperature. Temperature. Generally Generally solubility increases as temp. solubility increases as temp. increasesincreases

EXCEPTION:EXCEPTION: When the solute is a When the solute is a gas Increasing temp decreases gas Increasing temp decreases solubility and vice versa.solubility and vice versa.

3. Pressure For solid and liquid 3. Pressure For solid and liquid solutes no changes in solubility with solutes no changes in solubility with changes in pressure, changes in pressure, but for gases but for gases solubility increases with solubility increases with increasing pressure and vice increasing pressure and vice versaversa

Carbonated beverages are kept under Carbonated beverages are kept under pressure and when you decrease the pressure and when you decrease the pressure by opening them they lose pressure by opening them they lose the carbonation the carbonation

Saturated – Saturated – a solution that has a solution that has dissolved in it all the solute it dissolved in it all the solute it can normally hold at a given can normally hold at a given temperature.temperature. If any more solute is If any more solute is added it will fall to the bottomadded it will fall to the bottom

Unsaturated- Unsaturated- a solution that a solution that contains less solute than it can contains less solute than it can hold at a certain temperature. hold at a certain temperature. If If more solute is added it will dissolvemore solute is added it will dissolve

Supersaturated- Supersaturated- Under special Under special conditions, there are some conditions, there are some solutions that can actually hold solutions that can actually hold more solute than is present in more solute than is present in their saturated solutions at a their saturated solutions at a given temperature.given temperature.

If more solute is added all “extra” solute If more solute is added all “extra” solute immediately falls out of solutionimmediately falls out of solution

Examples sodium acetate NaCExamples sodium acetate NaC22HH33OO2 2

and sodium thiosulfate Naand sodium thiosulfate Na22SS22OO33

Molecule-ion attractionMolecule-ion attraction

a. the term molecule refers to a. the term molecule refers to a a polar solventpolar solvent while ions refers to while ions refers to an an ionic compoundionic compound

b. An ionic compound is placed in b. An ionic compound is placed in liquid ammonia, water or alcoholliquid ammonia, water or alcohol

c. Attraction between the c. Attraction between the positivepositive and and negative ionsnegative ions of the ionic of the ionic compound and the oppositely compound and the oppositely charged poles of the solvent charged poles of the solvent molecule.molecule.

d. This results in a d. This results in a hydrated ionhydrated ion if the if the solvent is solvent is waterwater

Preparation of a supersaturated solutionPreparation of a supersaturated solution

1. Add more solute to the 1. Add more solute to the solvent( usually water) than will solvent( usually water) than will dissolve at room temperaturedissolve at room temperature

2. Heat the solution until all the solute 2. Heat the solution until all the solute dissolves, do not boildissolves, do not boil

3. Gently place the hot solution in an ice 3. Gently place the hot solution in an ice bath and allow it to cool undisturbed.bath and allow it to cool undisturbed.

4. Once the solution is cooled to room 4. Once the solution is cooled to room temperature a supersaturated solution temperature a supersaturated solution exists.exists.

Dilute- Dilute- amount of solute dissolved amount of solute dissolved is small in relation to the amount is small in relation to the amount of solventof solvent. It is considered a weak . It is considered a weak solutionsolution

Concentrated – Concentrated – amount of solute amount of solute dissolved is large in relation to dissolved is large in relation to the amount of solvent. the amount of solvent. It is It is considered a strong solution.considered a strong solution.

Table F- Solubility GuidelinesTable F- Solubility Guidelines

Used to predict if various compounds Used to predict if various compounds dissolve in water.dissolve in water.

Solubility curvesSolubility curves

1. Graph of amount of solute in 100g 1. Graph of amount of solute in 100g of water versus temperatureof water versus temperature

2. TABLE G2. TABLE G

3. Tells the number of grams that 3. Tells the number of grams that needs to be dissolved in 100g of needs to be dissolved in 100g of water at a given temperature to water at a given temperature to make a SATURATED SOLUTION.make a SATURATED SOLUTION.

Examples:Examples: How many grams of KNOHow many grams of KNO33 needs be needs be

dissolved to produce a saturated dissolved to produce a saturated solution in 100g of water at 50C?solution in 100g of water at 50C?

How many grams of KNOHow many grams of KNO33 needs be needs be dissolved to produce a saturated dissolved to produce a saturated solution in 50g of water at 50C?solution in 50g of water at 50C?

How many grams of KNOHow many grams of KNO33 needs be needs be dissolved to produce a saturated dissolved to produce a saturated solution in 500g of water at 50C?solution in 500g of water at 50C?

5. Can be used to predict if a solution 5. Can be used to predict if a solution is saturated, unsaturated or is saturated, unsaturated or supersaturated.supersaturated.

a. saturated solutions fall on the a. saturated solutions fall on the curvecurve

b. unsaturated solutions fall below b. unsaturated solutions fall below the curvethe curve

c. supersaturated solutions fall c. supersaturated solutions fall above the curveabove the curve

6. Examples:6. Examples: A solution is prepared by dissolving A solution is prepared by dissolving

80 g of NaNO80 g of NaNO33 in 100 g of water at 30 in 100 g of water at 30 C. Is this solution unsaturated, C. Is this solution unsaturated, saturated or super saturated?saturated or super saturated?

A solution is prepared by dissolving A solution is prepared by dissolving 70g of NH70g of NH44Cl in 100g of water at 80 Cl in 100g of water at 80 C. Is this solution unsaturated, C. Is this solution unsaturated, saturated or supersaturated?saturated or supersaturated?

ConcentrationConcentration

1. Definition: 1. Definition: amount of solute amount of solute dissolved in a given amount of dissolved in a given amount of solventsolvent

2. The higher the value the more 2. The higher the value the more concentrated the solutionconcentrated the solution

4 Methods for expressing concentrations4 Methods for expressing concentrations

1.1. MolarityMolarity

a. number of moles of solute per a. number of moles of solute per liter of solutionliter of solution

b. Formula found on Table Tb. Formula found on Table T

Molarity = Molarity = moles of solutemoles of solute

Liter of solutionLiter of solution

Units: M or moles/litersUnits: M or moles/liters

2. Percent by mass-2. Percent by mass-

a. Used when a solid is dissolved a. Used when a solid is dissolved in a liquidin a liquid

% by mass = % by mass = mass of solute mass of solute x 100x 100

mass of solutionmass of solution

3. Percent by volume3. Percent by volume

a. Used when two liquids are a. Used when two liquids are mixed to form a solutionmixed to form a solution

% by volume = % by volume = volume of solutevolume of solute x 100 x 100

volume of solutionvolume of solution

4. Parts per million4. Parts per million

a. Specifies the number of parts a. Specifies the number of parts of solute in 1 million parts of of solute in 1 million parts of solutionsolution

b. Used when the amount of b. Used when the amount of solute is small compared to the solute is small compared to the amount of solventamount of solvent..

c. Formula on Table Tc. Formula on Table T

Ppm = Ppm = mass of solutemass of solute x 1,000,000 x 1,000,000

Mass of solutionMass of solution

d. units ppmd. units ppm

Preparing a solutionPreparing a solution

1. Calculate the number of grams of solute 1. Calculate the number of grams of solute that must be added using the correct that must be added using the correct formula from the information givenformula from the information given

2. Add this much solute to a volumetric flask 2. Add this much solute to a volumetric flask of the correct volume.of the correct volume.

3. Fill the flask about ¾ of the way with 3. Fill the flask about ¾ of the way with solvent (usually water)solvent (usually water)

4. Cap the flask and invert to mix. (repeat 4. Cap the flask and invert to mix. (repeat until all solute is dissolve)until all solute is dissolve)

5. Fill the flask to the line with solvent.5. Fill the flask to the line with solvent.

6. Invert to finish mixing.6. Invert to finish mixing.

Dilutions:Dilutions:

MM11VV11 = M = M22VV22

MM11 = molarity of original sample = molarity of original sample VV11 = volume of original sample = volume of original sample MM22 = molarity after dilution = molarity after dilution VV22 = volume of solution after dilution = volume of solution after dilution

Electrolytes and nonelectrolytesElectrolytes and nonelectrolytes

1.1. ElectrolyteElectrolyte

a. a. -compounds that conduct -compounds that conduct electricity in solutionelectricity in solution

b. contain mobile charged b. contain mobile charged particles(ions) in the solution particles(ions) in the solution

2. Strong 2. Strong electrolyte-electrolytes electrolyte-electrolytes that form large numbers of ions that form large numbers of ions in solution they cause the bulb in solution they cause the bulb of a conductivity apparatus to of a conductivity apparatus to glow brightly. glow brightly.

Examples: Ionic Solids, strong acids Examples: Ionic Solids, strong acids and bases and bases

3. Weak electrolyte- 3. Weak electrolyte- electrolytes electrolytes that are poor conductors- they that are poor conductors- they form few ions in solution and form few ions in solution and cause the bulb of the cause the bulb of the conductivity apparatus to glow conductivity apparatus to glow faintly.faintly.

Examples weak acids and bases such Examples weak acids and bases such as acetic acid and ammoniaas acetic acid and ammonia

4. Nonelectrolytes- non conductors 4. Nonelectrolytes- non conductors of electricity they do not produce of electricity they do not produce ions when placed in water and ions when placed in water and the bulb does not light at allthe bulb does not light at all

Examples: sugars, glycerineExamples: sugars, glycerine

Colligative propertiesColligative properties

1. Properties of solutions such as vapor 1. Properties of solutions such as vapor pressure, boiling point and freezing pressure, boiling point and freezing points points that depend upon the that depend upon the number of particles of solute number of particles of solute dissolved in a solution.dissolved in a solution.

2. Therefore properties such as vapor 2. Therefore properties such as vapor pressure, boiling point and freezing pressure, boiling point and freezing point point will be most affected if the will be most affected if the solute is strong electrolyte and solute is strong electrolyte and least affected if the solute is a least affected if the solute is a nonelectrolyte. nonelectrolyte.

BOTH WILL AFFECT THE PROPERTIES BOTH WILL AFFECT THE PROPERTIES JUST TO DIFFERENT EXTENTSJUST TO DIFFERENT EXTENTS

3. Solutes that are strong electrolyte 3. Solutes that are strong electrolyte break up into many ions therefore break up into many ions therefore there are more dissolved particles in there are more dissolved particles in the solution than for a the solution than for a nonelectrolyte.nonelectrolyte.

Boiling Point Elevations and Freezing Boiling Point Elevations and Freezing point depressionspoint depressions

1. When any substance is added to a 1. When any substance is added to a solvent the boiling point increases solvent the boiling point increases and the freezing point decreases. and the freezing point decreases. The increase or decrease is greatest The increase or decrease is greatest if the substance added is ionic if the substance added is ionic (strong electrolyte) and least if the (strong electrolyte) and least if the substance is molecular (weak or substance is molecular (weak or nonelectrolyte)nonelectrolyte)

Which of the following compounds Which of the following compounds when dissolved in water would lower when dissolved in water would lower the freezing point the most and why?the freezing point the most and why?

CC66HH1212OO66 NaCl CH NaCl CH33OH MgClOH MgCl22 AlCl AlCl33