1. Chemistry 1011 TOPIC TEXT REFERENCE Acids and Bases
Masterton and Hurley Chapter 4.2 (Review), 13, 14.1, 15.1 (page 427), 21.2 (page589)
Chemistry 1011 Slot 5

2. 13.1 The Bronsted-Lowry Acid-Base Model
YOU ARE EXPECTED TO BE ABLE TO:
Define an acid as a substance that produces hydrogen ions in aqueous solution (Arrhenius)
Identify common chemical reactions of acids.
Identify a Bronsted-Lowry acid-base reaction.
Identify conjugate acid-base pairs.
Define amphiprotic species.
Chemistry 1011 Slot 5

3. The Arrhenius Definition
An acid is a species that produces hydrogen ions in water
HCl(aq) H+(aq) + Cl-(aq)
A base reacts with an acid to produce a salt and water only
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
Some bases dissolve in water to give hydroxide ions
NaOH(aq) Na+(aq) + OH-(aq)
Some bases are insoluble in water
2HCl(aq) + CuO(s) CuCl2(aq) + H2O(l)
Chemistry 1011 Slot 5

4. The Bronsted-Lowry Definition
An acid is a proton (H+ ion) donor
A base is a proton acceptor
In an acid-base reaction, a proton is transferred from the acid to the base
HB(aq) + A-(aq) HA (aq) + B-(aq)
HB and HA are Bronsted-Lowry acids for the forward and reverse reactions
A- and B- are Bronsted-Lowry bases for the forward and reverse reactions
Chemistry 1011 Slot 5

5. Conjugate Acids and Bases
B- is the conjugate base of acid HB
HB is the conjugate acid of base B-
HB and B- are a conjugate pair
conjugate pair
conjugate base conjugate acid
HB(aq) + A-(aq) HA (aq) + B-(aq)
conjugate acid conjugate base
Chemistry 1011 Slot 5

6. Examples of Conjugate Pairs
Acid Base
HF(aq) H+(aq) + F-(aq)
HSO4-(aq) H+(aq) + SO4-(aq)
NH4+(aq) H+(aq) + NH3(aq)
Identify the conjugate pairs in the reaction
CN-(aq) + H2O(l) HCN(aq) + OH-(aq)
cb ca ca cb
Chemistry 1011 Slot 5

7. Amphiprotic Species
Some species can act as either Bronsted-Lowry acids or bases
HCO3-(aq) H+(aq) + CO32-(aq)
HCO3-(aq) + H+(aq) H2CO3(aq)
These species are known as amphiprotic
Chemistry 1011 Slot 5