Solutions/Acid & Bases Chapter 15 & 19

Solution are homogenous mixtures. Solutions are made up of 2 things: – A solute & a solvent. Water is the most common solvent in liquid solutions.

Soluble & Insoluble Dissolves in a solvent Example: –Sugar in water Will not dissolve in a solvent Example: –Sand is insoluble in water.

Miscible & Immiscible Two liquids that are soluble in one another Example: –Antifreeze & water –Acetic acid & water Two liquids not soluble in one another Example: –Oil & vinegar –Oil & water

Solute & Solvent What gets dissolved. The lesser amount of substance in a solution. Example: –Sugar –Salt What things dissolve in. The greater amount of substance in a solution. Example: –Water –Ethanol

Solvation Rules: Like dissolves like. Polar dissolves polar. Nonpolar dissolves nonpolar.

Solvation of salt cont… Formula units break apart & ions become attracted to charges of the water molecules.

Solvation of salt

Solvation of sugar (covalent) In polar molecules, water molecules have a stronger attraction to the polar molecules than they have to each other.

“What can affect solubility?” Two factors that affect rates of solutions. 1.Temperature 2.Pressure

Solvation & Crystallization Surrounding solute particles with solvent particles. Breaking apart. “Dissolving” Hydration Particles coming together. Dehydration

Saturated & Unsaturated Max amount of solute dissolves in a solvent at a temp/pres. Ex: –Concentrated or strong tea Less solute is dissolved than saturated. It can dissolve more. Ex: –Diluted or weak tea

Factors that affect solubility 1. Temperature: For solids- ↑ temperature, ↑ solubility For gases- ↑ temperature, ↓ solubility 2. Pressure: For gases in liquid- ↑ pressure, ↑ solubilty

Super saturated solution- a solution that contains more solute than saturated solutions at the same temp/pressure

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Henry’s Law- at a given temperature, solubility of a gas in a liquid is directly proportional to the pressure of a gas above the liquid. Example: a soda

15.2 Solution Concentration How much solute is dissolved in a specific amount of solvent is concentration

Describing concentration Qualitative: Concentrated or diluted

Describing concentration Quantitative: 1.Percent by volume 2.Molarity (M) 3.Molality 4.Normality

Molarity: (M)(mol/L)=moles of solute liters of solution

Example 1 A mL intravenous solution contains 5.10 g of glucose (C 6 H 12 O 6 ). What is the molarity of this solution? –Hint: glucose molar mass is 180. g/mol. Practice 1-3

15-3 Colligative Properties of Solutions Physical properties that are affected by the number of particles and not by their identity are colligative properties.

Examples of colligative properties include: 1. vapor pressure lower 2. boiling point elevation 3. freezing point depression 4. osmotic pressure

Solutions: –Solutes will not settle out –Will not scatter light –Cannot filter

15-4 Heterogeneous Mixtures Suspensions: –Settles out –Scatters light –Can be separated by filtering –Are large particles (>1000 nm) Examples: muddy water, fine sand in water

Colloids: –Don’t settle out –Scatters light –Can’t be filtered –Medium to small sizes (<1000 nm) –Examples: milk

Brownian motion is the random movement of colloid particles. Causes collision of particles preventing them from settling.

Tyndall effect: –Particles scatter light –Can be seen in suspensions & colloids Examples: ray of light through fog or smoke

Acid & Bases Chapter 19 Acids, bases, & salts are electrolytes because they conduct electrical current. An indicator is a compound that changes color to indicate the presences of an acid or base.

Characteristics of acids Sour taste Reacts with metals Neutralizes bases affects indicators –turns blue litmus red/pink –keeps phenolphthalein colorless –turns methyl orange red

Common Acids: Citric acid- in citrus fruits –(Lemons, oranges, etc) Acetic acid- vinegar Malic acid- apple Butyric acid- sour butter Lactic acid- sour milk; builds up in muscles during exercise.

Industrial acids: Sulfuric acid- (H 2 SO 4 ) most manufactored chemical in US; fertilizers Phosphoric acid- (H 3 PO 4 ) fertilizers; detergents Nitric acid- (HNO 3 ) fertilizers; explosives Hydrochloric acid- (HCl) used to “pickle” steel (remove surface impurities)

Review: Naming acids 1. Binary acids- (only 2 elements) “hydro________ic acid” –Ex. HBr –Ex. H 2 S 2. Oxyacids- (has polyatomic ions) “________ic acid” –Ex. HClO 3 –Ex. H 2 SO 4

Characteristics of Bases tastes bitter feels slimy affects indicators –pink litmus turns blues –phenolphthalein turns bright pink –methyl orange turns yellow

Common Bases: Ammonia- (NH 3 ) cleaning agent Lye- (NaOH) draino Milk of magnesia- (Mg(OH) 2 ) laxative Lime- (Ca(OH) 2 ) mortar for bricks, foul lines on fields

What is pH? pH is the negative logarithm of H +1 ion concentration pH= -log[H + ] pH range- 0  14 pH scale: acids  , neutral  7, base 

Example 2 What is the pH of a solution with the concentration [H+]= 1.0 x M? Practice 4. What is the pH of [H + ]=1.0x10 -2 ? 5. What is the pH of [H + ]=3.0x10 -6 ? pOH? 6. What is the pOH of [OH - ]=8.2x10 -6 ?

Ex. 3 What is the concentration (Molarity) of H+ of an acidic solution with the pH of 3.20? Practice: 7. Calculate the concentration of H+ of an acidic solution with the pH of 6.55.

Neutralization Neutralization Reaction- reaction between an acid & base to produce a salt & water Salt- made of the positive ion (from base) & the negative ion (from acid) Example: Mg(OH) 2 + HCl  Practice: H 3 PO 4 + Ca(OH) 2  Al(OH) 3 + H 2 SO 4 

Arrhenius vs Bronted-Lowry Acid is the sub. containing H Base is the sub. containing OH Ex. HCl & NaOH Acid is the sub. that loses the H+ Base is the sub. that gains the H+. involves conj. acid & bases H 2 O + NH 4 +  NH 3 + H 3 O +

Practice: Identify the following Bronsted-Lowry acids & bases. HC 2 H 3 O 2 +H 2 O  H 3 O + + C 2 H 3 O 2 -

Anhydrides are compounds that can become acids or bases when water is added. Ex. Which is the anhydride? –CO 2 + H 2 O  H 2 CO 3 Practice. Which is the anhydride? –CaO + H 2 O  Ca(OH) 2 –H 2 O + SO 2  H 2 SO 4