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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