ch. 8 solutions, acids, & bases i. how solutions form definitions types of solutions ...
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Ch. 8Solutions, Acids, & Bases
Ch. 8Solutions, Acids, & Bases
I. How Solutions Form Definitions Types of Solutions Dissolving Rate of Dissolving
A. DefinitionsA. Definitions
Solution – Solution – a mixture that has the same a mixture that has the same composition throughout the mixture; a composition throughout the mixture; a homogeneous mixturehomogeneous mixture
Solvent Solvent – what the solute is dissolved in (in greater quantity)
Solute Solute - substance being dissolved (in lesser quantity)
A. DefinitionsA. Definitions
Solute Solute - KMnO4 Solvent Solvent - H2O
Remember the difference between a a mixture and a compound.
o Compounds have the same (fixed) composition throughout.
o Mixtures can have a variable (different) composition throughout.
A. Definitions
Solubility – The maximum amount of solute that can be dissolved in the solvent at a given temperature.
A. Definitions
B. Types of SolutionsB. Types of Solutions
Saturated solutions – maximum amount of solute at a given temperature.
Unsaturated solutions – less than the max. amount of solute at a given temperature.
Supersaturated solutions – more than the max amount of solute at a given temperature; unstable
B. Types of SolutionsB. Types of Solutions
SATURATED SOLUTION
no more solute dissolves
UNSATURATED SOLUTIONmore solute dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
concentration
C. DissolvingC. Dissolving
SolvationSolvation
• occurs at the surface of the solute
• solvent particles surround solute particles (+/- attraction)
• solute particles are pulled into solution
C. DissolvingC. Dissolving
NaCl dissolving in waterNaCl dissolving in water
D. Rate of DissolvingD. Rate of Dissolving
Solids dissolve faster...Solids dissolve faster...
• more stirring
• small particle size(increased surface area)
• high temperature
D. Rate of DissolvingD. Rate of Dissolving
Gases dissolve faster...Gases dissolve faster...
• no shaking or stirring
• high pressure
• low temperature
Ch. 8Solutions, Acids, & Bases
Ch. 8Solutions, Acids, & Bases
II. Concentration & Solubility
A. ConcentrationA. Concentration
% by Volume% by Volume• usu. liquid in liquid• EX: 10% juice = 10mL juice + 90mL water
% by Mass% by Mass• usu. solid in liquid• EX: 20% NaCl = 20g NaCl + 80g water
A. ConcentrationA. Concentration
Concentrated solutionConcentrated solution • large amount of solute
Dilute solutionDilute solution • small amount of solute
A. ConcentrationA. Concentration
SATURATED SOLUTION
no more solute dissolves
UNSATURATED SOLUTIONmore solute dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
concentration
B. SolubilityB. Solubility
SolubilitySolubility• maximum grams of solute that will
dissolve in 100 g of solvent at a given temperature
• varies with temperature• based on a saturated solution
B. SolubilityB. Solubility
Solubility CurveSolubility Curve• shows the
dependence of solubility on temperature
B. SolubilityB. Solubility
Solids are more soluble at...Solids are more soluble at...• high temperatures.
Gases are more soluble at...Gases are more soluble at...• low temperatures.• high pressures
(Henry’s Law).
Ch. 8Solutions, Acids, & Bases
Ch. 8Solutions, Acids, & Bases
III. Particles in Solution “Like Dissolves Like” Electrolytes
A. “Like Dissolves Like”A. “Like Dissolves Like”
NONPOLAR
NONPOLAR
POLAR
POLAR
DetergentsDetergents• polar “head” with long nonpolar “tail”• can dissolve both types
B. ElectrolytesB. Electrolytes
ElectrolyteNon-
Electrolyte
solute exists asions only
- +
salt
- +
sugar
solute exists asmolecules
only
- +
acetic acid
WeakElectrolyte
solute exists asions and
molecules
B. ElectrolytesB. Electrolytes
DissociationDissociation• separation of +/-
ions when an ionic compound dissolves in water
B. ElectrolytesB. Electrolytes
IonizationIonization• breaking apart of
polar covalent molecules into ions when dissolving in water
Ch. 8Solutions, Acids, & Bases
Ch. 8Solutions, Acids, & Bases
I. Intro to Acids & Bases Definitions Properties Uses
A. AcidsA. Acids
• Contain at least one hydrogen atom that can be removed when the acid is dissolved in water.
• These form hydronium ions, H3O+.
HCl + H2O H3O+ + Cl–
A. BasesA. Bases
• Form hydroxide ions (OH-) in a water solution.
NH3 + H2O NH4+ + OH-
A. IndicatorsA. Indicators
• An organic substance that changes color in an acid or base.
ExamplesExamples::• litmus - red/blue• phenolphthalein - colorless/pink• goldenrod - yellow/red• red cabbage juice - pink/green
B. PropertiesB. Properties
sour taste
pH less than 7
corrosive
electrolytes
turn litmus red
react with metals to form H2 gas
bitter taste
pH greater than 7
corrosive
electrolytes
turn litmus blue
slippery feel
C. UsesC. Uses
H3PO4 - soft drinks, fertilizer, detergents
H2SO4 - fertilizer, car batteries
HCl - gastric juice
HC2H3O2 - vinegar
C. UsesC. Uses
NaOH - lye, drain and oven cleaner
Mg(OH)2 - laxative, antacid
NH3 - cleaners, fertilizer
Ch. 8Solutions, Acids, & Bases
Ch. 8Solutions, Acids, & Bases
II. Strength of Acids & Bases Strength vs. ConcentrationStrong vs. Weak pH
A. Strength vs. ConcentrationA. Strength vs. Concentration
Strong and weak – tells how easy the acid or base dissociates in solution.
Concentration – The amount of acid or base in a solution.
It is possible to have a dilute concentration of a strong acid that would be less harmful than a concentrated weak acid.
A. Strength of Acids & BasesA. Strength of Acids & Bases
The strength of an acid or base depends on how completely a compound separates into ions when dissolved in water.
Ions can carry an electric charge so a strong acid will carry more electricity than weak acid.
B. Strong vs. WeakB. Strong vs. Weak
Strong Acid/BaseStrong Acid/Base• 100% ions in water• strong electrolyte• HCl, HNO3, NaOH, LiOH
Weak Acid/BaseWeak Acid/Base• few ions in water• weak electrolyte• HC2H3O2, NH3
- +
- +
B. Strong AcidsB. Strong Acids
Acids that ionize almost completely in a solution are strong acids.
Ex: HCl, HNO3, and H2SO4
B. Strong BasesB. Strong Bases
Bases that dissociate completely in a solution are strong bases.
Ex: NaOH
C. pH ScaleC. pH Scale
0
7INCREASING
ACIDITY NEUTRALINCREASING
BASICITY
14
pH pH (potential of Hydrogen)(potential of Hydrogen)• a measure of the concentration of H+
ions in a solution • measured with a pH meter or an
indicator with a wide color range (0-14)
C. pH ScaleC. pH Scale
pH of Common SubstancespH of Common SubstancespH of Common SubstancespH of Common Substances
Which of the following "molecular" pictures best represents a concentrated solution of the weak acid HA?
ConcepTestConcepTest
A B
Is the following statement TRUE or FALSE?
• A strong acid has a lower pH than a weak acid.
• FALSE - Strong/weak refers to amount of ionization whereas pH refers to concentration of H+.
ConcepTestConcepTest
Ch. 8Solutions, Acids, & Bases
Ch. 8Solutions, Acids, & Bases
III. Neutralization Neutralization Reaction
A. Neutralization ReactionA. Neutralization Reaction
Chemical reaction between an acid and a base.
Products are a salt (ionic compound) and water.
ACID + BASE ACID + BASE SALT + WATER SALT + WATER
HCl + NaOH HCl + NaOH NaCl + H NaCl + H22OO
Neutralization does not always mean pH = 7.
=
A. Neutralization ReactionA. Neutralization Reaction
KOH + HNO3 H2O + KNO3
Acid
Base
Salt
HNO3
KOH
KNO3
A. Neutralization ReactionA. Neutralization Reaction