acids & bases. naming review binary acids 1.start the acid name with “hydro-“ 2.add the root...
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Acids & BasesAcids & Bases
Naming ReviewNaming Review
Binary Acids1. Start the acid name with “hydro-“2. Add the root of the second element with the suffix “ic”3. Add the word “acid” EX. HCl- hydrochloric acid
Polyatomic Acids• Use the root name of the polyatomic• Add “ic” if the polyatomic ends in –ate What I ATE was ICky• Add “ous” if the polyatomic ends in –ite I took a bITE it was deliciOUS• Add the word “acid”
DefinitionsDefinitions
AcidsAcids• Ionize to form hydronium ions (H3O+) in water
(Arrhenius)• Proton donor (Bronsted-Lowry)• Electron-pair acceptor (Lewis)
HCl + H2O H3O+ + Cl–
DefinitionsDefinitions
BasesBases• Dissociate or ionize to form hydroxide ions (OH-) in water (Arrhenius)• Proton acceptor (Bronsted - Lowry)• Electron-pair donor (Lewis)
NH3 + H2O NH4+ + OH-
Acid-Base ReactionsAcid-Base Reactions
Conjugate Base – the species that remains Conjugate Base – the species that remains after the acid has given up a protonafter the acid has given up a proton
Conjugate Acid – the species that is formed when the base gains a proton
HCl + H2O H3O+ + Cl-acid conjugate
baseconjugate acid
base
HF + H2O F- + H3O+
Acid
Base
Conjugate Acid
Conjugate Base
HF
H2O
H3O+
F-
Acid-Base ReactionsAcid-Base Reactions
PropertiesProperties
sour taste
corrosive
electrolytes
turn litmus red
react with metals to form H2 gas
bitter taste
corrosive
electrolytes
turn litmus blue
slippery feel
UsesUses
H3PO4 - soft drinks, fertilizer, detergents
H2SO4 - fertilizer, car batteries
HCl - gastric juice
HC2H3O2 - vinegar
UsesUses
NaOH - lye, drain and oven cleaner
Mg(OH)2 - laxative, antacid
NH3 - cleaners, fertilizer
Strong vs. WeakStrong vs. Weak
Strong Acid/BaseStrong Acid/Base• 100% ions in water – completely dissociate• strong electrolyte
Weak Acid/BaseWeak Acid/Base• few ions in water –
incomplete dissociation• weak electrolyte
- +
- +
Strong AcidsStrong Acids
H2SO4 Sulfuric Acid
HClO4 Perchloric Acid
HCl Hyrochloric AcidHNO3 Nitric Acid
HBr Hydrobromic AcidHI Hydroidic Acid
Strong BasesStrong Bases
Ca(OH)2 Calcium hydroxide
Sr(OH)2 Strontium hydroxide
Ba(OH)2 Barium hydroxide
NaOH Sodium hydroxideKOH Potassium hydroxideRbOH Rubidium hydroxideCsOH Cesium hydroxide
pH ScalepH Scale
0
7INCREASING
ACIDITY NEUTRALINCREASING
BASICITY
14
pHpH• a measure of the concentration of
H3O+ ions in solution• measured with a pH meter or an
indicator with a wide color range
pH ScalepH 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
ACID + BASE ACID + BASE SALT + WATER SALT + WATER
HCl + NaOH HCl + NaOH NaCl + H NaCl + H22OO
Neutralization does not always mean pH = 7.
=
Neutralization ReactionNeutralization Reaction
KOH + HNO3 H2O + KNO3
Acid?
Base?
Salt?
HNO3
KOH
KNO3
Neutralization ReactionNeutralization Reaction
IndicatorsIndicators
IndicatorIndicator• Substance that changes color in an acid or base• Acid-base indicators are very weak acids and bases that change
color when they:– accept a proton from acid – donate one to a base
Indicator Color of acid Color of base
Litmus paper Red Blue
Phenolphthalein Colorless Pink
Goldenrod Yellow Red
Bromothymol blue Yellow Blue
TitrationTitration
The controlled addition and measurement of the amount of a solution of known concentration required to react completely with a measured amount of solution of unknown concentration
Equivalence Point – the point at which two solutions used in a titration are present in chemically equivalent amounts• Occurs at a pH that is halfway between the two curves
End Point – the point at which an indicator changes color
TitrationTitration
Beaker – vinegar + phenolphthaleinBuret – sodium hydroxide
As soon the liquid in the beaker
changes color, stop the dropping. Notice the amount
of titrating solution used
Titration CurvesTitration Curves
Titration CurvesTitration Curves
strong acid / strong base weak acid / strong base
H2O: Acid or Base?H2O: Acid or Base?
Amphoteric – a species that can react as either an acid or a base
NH3 + H2O NH4+ + OH-
HCl + H2O H3O+ + Cl– acid base
base acid
Self-Ionization of H2OSelf-Ionization of H2O
Two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton
H2O + H2O <----> H3O + OH⁺ ⁻ At 25 C – the concentrations of H3O + OH in pure water are 1.0x10⁺ ⁻ -7M [ H3O ] = 1.0x10⁺ -7M [ OH ] = 1.0x10⁻ -7M Ionization constant of water is Kw
Kw = [ H3O ] [ OH ]⁺ ⁻
Kw = [ H3O ] [ OH ] = (1.0x10⁺ ⁻ -7M)(1.0x10-7M) = 1.0x10-14M2
Ionization ProblemsIonization Problems
A 1x10-4M solution of HNO3 has been prepared for a lab experiment.
a. Calculate [ H3O ] ⁺
b. Calculate [ OH ]⁻
pH & ConcentrationpH & Concentration
pH of a solution is the negative of the common logarithm of the hydronium ion concentration
pH = -log [ H3O ] ⁺
neutral solution at 25C [ H3O ] = 1.0x10⁺ -7MpH = -log (1.0x10-7) = -(-7) = 7
pOH = -log (1.0x10-7) = -(-7) = 7
pH + pOH = 14
Kw= [ H3O ] [ OH ] =1.0x10⁺ ⁻ -14M2
-log(1.0x10-14) = 14
pH & Conc. CalculationspH & Conc. Calculations
1. What is the pH of a 1x10-3M NaOH solution?
2. What is the pH of a solution if the [ H3O ] ⁺is 3.4x10-5M?
3. Determine the hydronium ion of an aqueous solution that has a pH of 4.0
pH & Conc. CalculationspH & Conc. Calculations
4. The pH of a solution is measured and determined to be 7.52
a. What is the hydronium ion concentration?
b. What is the hydroxide ion concentration?
c. Is the solution acidic or basic?