Unit 13 - Solutions Solution – a homogeneous mixture of two or more substances Solvent: dissolving medium Ex: water Solute: substance that dissolves Ex: sugar, salts

Classification of Mixtures: true solution, suspension, and colloids 1. True solution: when a solute is dispersed throughout a solvent and form a homogeneous mixture (single phase) Ex: sugar+water; salt + water

2. Suspension: particles of a solute are huge compared to molecules of a solvent and form a heterogeneous mixture. Ex: muddy water, orange juice (filtration) 3. Colloids: particles are suspended through out the solvent. It may appear to be homogeneous, but examination (tyndall effect) shows that they are not a true solution.

Ex: mayonnaise (emulsion), milk, butter, gelatin, whipped cream, fog. smoke, mist, paints, glue. Tyndall Effect: distinguish true solution and colloid by passing a beam of light. Emulsion: liquid suspended in a liquid.

Unit 13 - Solutions SUSPENSION COLLOIDSOLUTIONS Completely Settle Out Do not Settle Out Do not Settle Out Pass Changed Pass Unchanged Pass Unchanged (Separated) Through Filter Paper Through Filter Paper Separated bySeparated by Not separated by Membranesby Membranes by Membranes Scatter LightScatter LightNot Scatter Light Not Affect ColligativeAffect ColligativeNot Affect Colligative PropertyPropertiesProperty > 100 nm100 nm – 10 nm< 10 nm

1. Brownian Motion: Continuous motion of colloidal properties, random 2. Tyndall Effect: Light scattering by colloidal particles. “ Like dissolves Like.” Definition:Substances with similar bonding are mutually soluble – Miscible Examples 1. HOH with Alcohol Polar/ Polar 2. HOH with Glycerol Polar/ Polar 3. HOH with salt Polar/ Ionic 4. Oil with gasoline Covalent/ Covalent

1. Aqueous = HOH based 2. Gaseous = Gas based 3. Other = Liquid/Solid/ Gas 4. Alloys= Metals- 2 or more (melt the solidify) SOLVENT- The dissolving medium-large mass/volume SOLUTE - The substance be dissolved- small mass/volume

Types of Solutes: 1. Electrolytes: conduct electric current. Ex: salt water 2. Nonelectrolytes: non conduct electric current. Ex: sugar water Factors affecting the rate of dissolution: 1. Increasing the surface area of the solute 2. Agitating a solution 3. Heating a solution

Solubility: the amount of solute is dissolved by a solvent at a given temperature. Unsaturated solution: more solute can be dissolved. Saturated solution: the maximum amount of dissolved solute in a solution Supersaturated solution: a solution that has more dissolved solute than a saturated solution at the same conditions.

Types of Solutions: SoluteSolventExample gasgasdeep sea gas (He in O 2 ) gasliquidsoda (CO 2 in water) gassolid stove lighter (H2 in platinum) liquidgaswater vapor in air liquidliquidantifreeze in water liquidsolid Hg in Sn/Ag-dental amalgam

Solids Liquids Gases 1 S 2L2L 3G3G Alloy (Jewelry Ag & Au) Dental Amalgam (Silver/ Hg) Gas Stove Lighter (Pd/H 2 ) Salt Water (HOH/NaCl) Vinegar (Acetic Acid/HOH) Carbonate Beer (HOH/CO 2 ) Air Naphthalene (Moth Balls) Humidity (Air/ HOH) Deep Sea Gas (He/O 2 )

1. Solvent-Solvent Dissociation ( Solvation) (Hydration) 2. Solute-SoluteDissociation 3. Solvent-SoluteAssociation H +,--,0 Rate of Dissolving 1. Heat Solvent 2. Powder Solute 3. Stirring Solution (Agitate) 4. Adjust Volume of Solvent v. Solute

Factors Temperature Limits 1 S/S 2 S/L 3 S/G L D L Melt No L D L Melt No L D L Adsorbs/ Absorbs Pressure No Surface Area of Solid

Factors Temperature Limits 1 L/S 2 L/L 3 L/G L D L Powder Agitate Yes T, Solubility Yes L D L No L D L Pressure Henry’s Law Yes T, Solubility Yes

Factors Temperature Limits 1 G/S 2 G/L 3 G/G Nature of Solute Gravity NoYes Volume of Gas Pressure Availability of Solute Yes T, Solubility Yes Temp. & Volume No

Henry’s Law: Solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid. Solubility:the amount of solute is dissolved by a solvent at a given temperature.

Saturation: Quantity of Solute per Volume (Mass) Solvent Unsaturated- holding less than max. under the conditions Saturated- Maximum Solute per Unit of Solvent L/S Temp. sensitive L/G Temp. & Pressure Sensitive Supersaturated- holding greater than Max. under specific condition. L/S Heat, Add Solute, Cool L/G Keep under pressure

Return to Saturation 1. Addition of a seed crystal; Shock “ping”, agitate 2. Sudden Temp. Change Cooling 3. Sudden Reduction in Pressure (gases only) DILUTE vs. COCENTRATED: Add solvent/ remove solvent

SOLUTION EQUILIBRIUM Definition: Physical state in which opposing processes of dissolving & crystallizing occur at equal rate. LeChatelier: Stress on a system causes a shift in the equilibrium of a system “Stress”:1. T 2. P 3.Agitation

AT “0”C AT 20 CAT 40 CAT 60 CAT 80 CAT 100 C 1 Sugar C 12 H 22 O 11 2 NaCl 3 Li 2 CO g204 g238 g287 g362 g487 g 35.7 g36.0 g36.6 g37.3 g38.4 g39.8 g 1.54 g1.33 g1.17 g 1.01 g.85 g.72 g

Temperature MASSMASS “_” Curve “0” Curve “+” curve

Heat of a Solution: The difference between the heat contents of a solution and the H of its components. Exothermic: Heating; - H ;KOH,NaOH Endothermic: Cooling; + H; KNO 3, AgNO 3 Isothermic: No Change “Neutral”; zero H; C 2 H 3 OOH(1), NaCl