Acids, Bases, & Salts Acids, Bases, & Salts
PropertiesProperties
Taste Sour. Can sting skin if open (cut).
React with metals to produce H2 gas.
Disassociate in water to produce ions that conduct electricity. (ELECTROLYTE)
Acids cause indicators to change color.Blue litmus paper turns red!
PropertiesProperties
Taste Bitter. Feel slippery to touch. Do not react with metals. Disassociate in water to produce ions that
conduct electricity. (ELECTROLYTE) Bases cause indicators to change color.
Red litmus paper turns blue!
&
Neutralize each other in what is called a Neutralization Reaction.
&
•Arrhenius AcidsArrhenius Acids form hydrogen ions (H+)
• HCl (hydrochloric acid)HCl (hydrochloric acid)
• HNOHNO33 (nitric acid) (nitric acid)
• HCHC22HH33OO22 (acetic acid) (acetic acid)
• HH22SOSO44 (sulfuric acid) (sulfuric acid)
• HH22COCO33 (carbonic acid) (carbonic acid)
• HH33POPO44 (phosphoric acid) (phosphoric acid)
DefinitionsDefinitions
•Arrhenius BasesArrhenius Bases form hydroxide ions (OH-)
• NaOH (sodium hydroxide)NaOH (sodium hydroxide)• KOH (potassium hydroxide)KOH (potassium hydroxide)
• Mg(OH)Mg(OH)22 (magnesium hydroxide) (magnesium hydroxide)
• Ca(OH)Ca(OH)22 (calcium hydroxide) (calcium hydroxide)
• Ba(OH)Ba(OH)22 (barium hydroxide) (barium hydroxide)
OH! It’s a base!
DefinitionsDefinitions
Always produce a salt and water
&
HCl + NaOH HCl + NaOH NaCl + H NaCl + H22OO
ACID + BASE ACID + BASE SALT + WATER SALT + WATER
&
DefinitionsDefinitions
Brønsted-LowryBrønsted-Lowry
HCl + H2O Cl– + H3O+
•AcidsAcids are hydrogen ion (H+) donors. •BasesBases are hydrogen ion (H+) acceptors.
baseacid
DefinitionsDefinitions
Types of Acids:Types of Acids:• Monoprotic AcidsMonoprotic Acids – have 1 proton to donate.
• Diprotic AcidsDiprotic Acids – have 2 protons to donate.
• Triprotic AcidsTriprotic Acids – have 3 protons to donate. HCl, HNO3, HF
H2SO4, H2CO3, H2S
H3PO4
Hydronium IonHydronium Ion
Produced when an acid dissociates in water and the water picks up the
hydrogen ion.
H3O+
H
HH H H
H
ClClO O
–+
Brønsted-Lowry Acids & BasesBrønsted-Lowry Acids & BasesBrønsted-Lowry Acids & BasesBrønsted-Lowry Acids & Bases
What part does water play?What part does water play?
H2O + HNO3 H3O+ + NO3–
AcidBase
What part does water play?What part does water play?
Water is amphoteric: can act as an can act as an
acid or a acid or a base.base.
NH3 + H2O NH4+ + OH-
Base Acid
Conjugate Acid – Base PairsConjugate Acid – Base Pairs
When a base gains a proton, it becomes its conjugate acid.When a base gains a proton, it becomes its conjugate acid. When an acid loses a proton, it becomes its conjugate base.When an acid loses a proton, it becomes its conjugate base.
HCl + H2O Cl– + H3O+
conjugate acidconjugate base
baseacid
Conjugate Acid – Base PairsConjugate Acid – Base Pairs
Pairs are joined together by the loss and gain of a proton.Pairs are joined together by the loss and gain of a proton. Acid & Base – Reactants side.Acid & Base – Reactants side. Conjugate Base & Conjugate Acid – Products side.Conjugate Base & Conjugate Acid – Products side.
NH3 + H2O NH4+ + OH-
acidbase conjugateacid
conjugatebase
Strength of Conjugate Acid-Base PairsStrength of Conjugate Acid-Base Pairs
The stronger the acid …
The weaker its conjugate base.
The weaker its conjugate acid.
The stronger the base …
Conjugate Acid – Base PairsConjugate Acid – Base Pairs
Determining Strengths of Acids and Bases
Determining Strengths of Acids and Bases
StrengthStrength
Strong Acids – Dissociate almost completely in water to produce HStrong Acids – Dissociate almost completely in water to produce H33OO++ ions ions Strong Bases – Strongly attract hydrogen ions in water, thus leaving OHStrong Bases – Strongly attract hydrogen ions in water, thus leaving OH--
- +
HCl
HNO3
H2SO4
NaOH
KOH
HBr
HI
HClO4
STRONG ACIDS STRONG
BASES
Ca(OH)2
CaO
StrengthStrength
Weak Acids – Dissociate slightly in water to produce HWeak Acids – Dissociate slightly in water to produce H33OO++ ions. Do not readily dissociate. ions. Do not readily dissociate. Weak Bases – react only partially with water to form OHWeak Bases – react only partially with water to form OH-- ions. ions.
NH3
H2NNH2
WEAK
ACIDS
WEAK BASES
CO32-2-
PO43-3-
- +
HF
CH3COOH
H3PO4
H2CO3
HCN
HCl + H2O H3O+ + Cl–
Strong Acid: SINGLE ARROW
DOUBLE ARROWWeak Acid:
HC2H3O2 + H2O H3O+ + C2H3O2–HC2H3O2 + H2O H3O+ + C2H3O2–
CaO Ca2+ + O2–
Strong Base: SINGLE ARROW
DOUBLE ARROWWeak Base:
CO32-
+ H2O
O2– + H2O 2OH–
HCO3- + OH–
Strong & WeakStrong & Weak
Acid Dissociation ConstantAcid Dissociation Constant
Ka = [H3O+][A-]
[HA]
Kais a measure of the strength of an acid.
HA(aq) + H2O (l)
The greater the Ka, the stronger the acid!
H3O+ (aq) + A–(aq)
Each ionization resultsin a different Ka value.
If the acid is diprotic or triprotic, the loss of each hydrogen
is a separate ionization.
Base Dissociation ConstantBase Dissociation Constant
Kb = [HB][OH-]
[B]
Kbis a measure of the strength of a base.
B(aq) + H2O(l) HB(aq) + OH–(aq)
The greater the Kb, the stronger the base!
Practice Problem #1Practice Problem #1
Acetic acid is a weak monoprotic acid. If the initial concentration of acetic acid is 0.200 M and the equilibrium concentration of H3O+ is 0.0019 M, calculate Ka for acetic acid.
Ka =[H3O+][A-]
[HA]
HA(aq) + H2O(l) H3O+(aq) + A–(aq)
Practice Problem #1Practice Problem #1
Ka =[H3O+][A-]
[HA]
HA(aq) + H2O(l) H3O+(aq) + A–(aq)
Use Stoichiometry!The reaction produces an A- ion
for every H3O+ ion.
[H3O+] = [A-]
Practice Problem #1Practice Problem #1
Ka =[H3O+][A-]
[HA]
HA(aq) + H2O(l) H3O+(aq) + A–(aq)
The equilibrium concentration of
HA equals its initial concentrationminus the amount
that ionizes.
[HA] = 0.200M – 0.0019M
[HA] = 0.1981M
Practice Problem #1Practice Problem #1
Ka =[H3O+][A-]
[HA]
HA(aq) + H2O(l) H3O+(aq) + A–(aq)
[H3O+] = [A-] = 0.0019M
[HA] = 0.1981M
=(0.0019M)(0.0019M)
(0.1981M)
= 1.8 x 10-5
Acid-Base Properties of SaltsAcid-Base Properties of Salts
Salts dissociate in water to form H3O+ or OH-
Knowing what type of acid and base formed the salt helps predict salt solution acid-base properties.
Acid-Base Properties of SaltsAcid-Base Properties of Salts
RULES:
Strong Acid + Strong Base Neutral Salt
Strong Acid + Weak Base
Weak Acid + Strong Base
Weak Acid + Weak Base
Acidic Salt
Basic Salt
Cannot predictvery easily
HCl + NaOH Neutral Salt
NaClSTRONGACID & BASE
NH3 + HClAcidic
Salt
NH4Cl
STRONGACID
WEAKBASE
NaOH + H2CO3
BasicSalt
Na2CO3
WEAKACID
STRONGBASE
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