Conjugate acid–base pair:
According to the Brønsted–Lowry concept, a conjugate acid–base pair consists of two species that differ by one proton (H+).
• An acid loses a proton to form its conjugate base.
• A base gains a proton to form its conjugate acid.
Conjugate acid/base of the given species:
(i) HNO2
HNO2 ⇌ H+ + NO2−
Conjugate base: NO2−
(ii) CN−
CN− + H+ ⇌ HCN
Conjugate acid: HCN
(iii) HClO4
HClO4 ⇌ H+ + ClO4−
Conjugate base: ClO4−
(iv) F−
F− + H+ ⇌ HF
Conjugate acid: HF
(v) OH−
OH− + H+ ⇌ H2O
Conjugate acid: H2O
(vi) CO
CO + H+ ⇌ HCO+
Conjugate acid: HCO+
(vii) S2−
S2− + H+ ⇌ HS−
Conjugate acid: HS−
Summary Table:
| Species | Conjugate Acid | Conjugate Base |
|---|---|---|
| HNO2 | — | NO2− |
| CN− | HCN | — |
| HClO4 | — | ClO4− |
| F− | HF | — |
| OH− | H2O | — |
| CO | HCO+ | — |
| S2− | HS− | — |