Acids and Bases
Acids and Bases
Part 2
Do Now
Do Now
• Compare
Compare the definitions of Arrhenius and the definitions of Arrhenius and
Bronsted‐Lowry Acids and Bases.
• What does conjugate mean?
Acid‐Base
Acid
Base Reactions
Reactions
• One
One molecule or ion passes a proton to molecule or ion passes a proton to
another molecule or ion
• The molecule or ion that loses the proton is an The molecule or ion that loses the proton is an
acid
• The molecule or ion that accepts the proton
Th
l l
i
h
h
i
is a base
• Ex: NH3(aq) + H2O(l) ÅÆ NH4+(aq) + OH‐(aq)
Acid‐Base
Acid
Base Reactions
Reactions
• Conjugate base= the species that remains after a Bronsted j g
p
Lowry acid has donated a proton.
• Conjugate acid= the species that forms after a Bronsted Lowry b
base has accepted a proton.
h
t d
t
** Bronsted‐Lowry acids and bases are on the reactant side.
** Conjugate acids and bases are on the product side.
The stronger the acid or base, the weaker the conjugate.
• An acid always has one more proton (H) than its conjugate base.
base
• Water is amphoteric = can behave as an acid or a base Amphoteric Species
Amphoteric Species
• Amphoteric
Amphoteric species have properties of both species have properties of both
acids and bases.
• Ex: HCO
Ex: HCO3‐(aq) + NH
+ NH3(aq) ÅÆ CO322‐(aq) + NH
+ NH4+
• Ex: HCO3‐(aq) + H3O+ ÅÆ H2CO3(aq) + H2O(l)
Conjugate Acid‐Base
Conjugate Acid
Base Pairs
Pairs
Acid
Conjugate Base
Hydrochloric acid, HCl
Chloride ion, Cl‐
Sulfuric acid, H2SO4
Hydrogen sulfate ion, HSO4‐
Hydronium ion, H
ion H3O+
Water H2O
Water, H
Hydrogen sulfate ion, HSO4‐
Sulfate ion, SO42‐
Hypochlorous acid, HOCl
Hypochlorite ion, ClO‐
Dihydrogen phosphateion, H2PO4‐
Monohydrogen phosphate ion, HPO42‐
Ammonium ion, NH4+
Ammonia, NH3
Hydrogen carbonate ion, HCO3‐
Carbonate ion, CO32‐
Water, H2O
Hydroxide ion, OH‐
Conjugate Acid
Base
pH Review Questions
pH Review Questions
• What do pH values indicate?
What do pH values indicate?
• What do they measure?
h d h
?
pH
• pH
pH = a measure of the concentration of H
= a measure of the concentration of H+ or or
H3O+ in solution (Power of Hydrogen)
• Low pH = highly acidic (lots of H
Low pH = highly acidic (lots of H+ or H
or H3O+)
• [H+] = concentration of hydrogen ions
pH of Common Substances
pH of Common Substances
Calculating pH
• The pH scale is a log scale, meaning that if you increase or decrease by one number on the pH scale th
the concentration of H
t ti
f H+ or H
H3O+ increases or i
decreases by 10
• A decrease of ONE on the pH scale is a 10X increase in H+ ion concentration!
in H+ ion concentration!
• There is a higher concentration of H+ ions in an acid with a pH of 1 than in an acid with a
an acid with a pH of 1 than in an acid with a pH of 2. pH of 1 is 100 times more acidic than a pH of 3
a pH of 3 pH and [H
pH
and [H+]
• pH
pH 5
5 Æ pH 4
pH 4
• What happens to the concentration of H+
ions?
– pH of 4 is more acidic than pH of 5
– pH 4 has 10x the amount of hydrogen ions than H 4 h 10 h
fh d
i
h
pH 5
pH Practice Questions
1. Solution A has a pH of 3 and solution Z has a pH of 6. How many times greater is the hydronium ion concentration in solution A than the hydronium ion concentration in solution
solution A than the hydronium ion concentration in solution Z?
A) 100 B) 2 C) 3 D) 1,000
2. As the pH of a solution is changed from 3 to 6, the concentration of hydronium ions
i
fh d i
i
A) increases by a factor of 3
B) increases by a factor of 1 000
B) increases by a factor of 1,000
C) decreases by a factor of 1,000
)
y
D) decreases by a factor of 3
3. The pH of an aqueous solution changes from 4 to 3 when the hydrogen ion concentration in the solution is
A) increased by a factor of 10
B) increased by a factor of 1
C) decreased by a factor of 1
)
b f
f
D) decreased by a factor of 10
4. A solution with a pH of 2.0 has a hydronium ion concentration ten times greater than a solution with a pH of
A) 0.20 B) 1.0 C) 3.0 D) 20.
5. What is the pH of a solution that has a hydronium ion concentration 100 times greater than a solution with a pH of 4?
concentration 100 times greater than a solution with a pH of 4?
A) 5 B) 2 C) 3 D) 6
6. Which change in pH represents a hundredfold increase in the concentration of hydronium ions in a solution?
A) pH 2 to pH 1 C) pH 1 to pH 3 B) pH 3 to pH 1 D) pH 1 to pH 2