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

• http://www.youtube.com/watch?v=D1PDE5OawuI&edufilter=iaYy5cltW5JHB2qLmddDPg

• 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 100.5 mL intravenous solution contains 5.10 g of glucose (C6H12O6). 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- (H2SO4) most manufactored chemical in US; fertilizers

• Phosphoric acid- (H3PO4) fertilizers; detergents

• Nitric acid- (HNO3) 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. H2S

• 2. Oxyacids- (has polyatomic ions) “________ic acid”– Ex. HClO3

– Ex. H2SO4

• Characteristics of Bases

• tastes bitter

• feels slimy

• affects indicators– pink litmus turns blues– phenolphthalein turns bright pink– methyl orange turns yellow

Common Bases:

• Ammonia- (NH3) 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- 014

• pH scale: acids 0-6.99, neutral 7, base 7.01-14

Example 2

• What is the pH of a solution with the concentration [H+]= 1.0 x 10-7 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:

• H3PO4 + Ca(OH)2

• Al(OH)3 + H2SO4

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

H2O + NH4+ NH3 + H3O+

• Practice:

• Identify the following Bronsted-Lowry acids & bases.

• HC2H3O2 +H2O H3O+ + C2H3O2-

• Anhydrides are compounds that can become acids or bases when water is added.

• Ex. Which is the anhydride?– CO2 + H2O H2CO3

• Practice. Which is the anhydride?– CaO + H2O Ca(OH)2

– H2O + SO2 H2SO4