Acids and Bases
Ch. 14
What is an Acid?
• Hydrochloric Acid, Vinegar, sulfuric acid…
• A covalent compound that produces H+ ion
when dissolved in water
• Hydronium ions; HA + H2OH3O+ + A• Ionization
– Creation of ions from a covalent
compound
• Sour taste
• pH less than 7
• Usually have an H at the start of their
chemical formula:
HCl
HC2H3O2
H2SO4 Why do acids burn us?
Acidic Hydrogen
• Hydrogen given up by acid during the reaction
• Monoprotic:
– Donate 1 H+
• Ployprotic:
donate more than one H+
– Diprotic
• Donate 2 H+
– Triprotic
• Donate 3 H+
What is Base?
• Sodium Hydroxide, Ammonia, Soap…
• A compound that produces OH- ions
when dissolved in water
• Hydroxide ions; B + H2O HB+ + OH• Water soluble ionic compounds
• Bitter taste; slippery texture
• pH greater than 7
• Usually have an OH at the end of the
chemical formula:
NaOH
KOH
Ca(OH)2
Formation of Acids and Bases
• Anhydrides- compounds that react with water to
produce acids or bases
• Acidic anhydrides:
–Nonmetal oxides
• Basic anhydrides:
–Metal oxides
Acid and Base Strength
•• Strong
bases:
Strength
is determined by
– Produce
and conjugate
amount
ofOHdissociation
acid acids:
• Strong
– LiOH, NaOH, KOH
– Produce H+ and a
• Weak
bases: base
conjugate
– Produce OH-, conjugate acid,
– and
HCl,undissociated
HNO3, H2SO4base
• Weak
– NH3,acids:
NH4OH, HSProduce H+,
conjugate
–– Conjugate
base
formed from
base,acid,
and HCOO
undissociated
weak
acid in NOT the same as
• Strength
– HF, CH3COOH, HCOOH
concentration
–– Strength
is pH
Conjugate
acid made by
+
a weak base, is
NH
– Concentration
molarity
4
pH Scale
• S.P.L. Sorenson; 1909
• pH  “pouvier d’hydrogene”
 “Power of Hydrogen”
• Negative log scale of [H+]
pH= -log [H+]
Water has a pH 7
[H+] = 1 x 10-7
[OH-] = 1 x10 -7
Acids= [H+] > [OH-]
Bases= [OH-] > [H+]
• pOH= -log[OH-]
• pH + pOH = 14
pH Scale
• Jumps in pH scale is equal to 10 fold jump in [H+]
pH 3 is ten times more [H+] than pH 4
pH 10 and pH 8? 100 times
pH 11 and pH 7? 10,000 times
• Calculations with pH:
• A solution has 1.0x10-11 M [H+]
-11]= 11
pH=
-log[1.0x10
a) What is the pH?
b) What is the pOH? pOH= 14-11= 3
c) What is the [OH-]? [OH-]= 1.0x10 -3
d) Is it an acid, base, or neutral? Base, pH=11
Identifying Acids and Bases
• Acid-Base Indicators
–Chemicals dyes that change colors
depending on the strength of the acid or
base
• Litmus paper
–Blue paper changes Red = Acid
–Red paper changes Blue = Base
• Liquid indicators