Writing acid-base reactions follows all the general rules of writing balanced equations. In this case, you know that one reactant (your acid) will be losing a proton during the reaction (and becoming one unit less positive / more negative along the way), and that the proton will be added to your basic reactant (and also gaining the proton’s positive charge).
Write separate equations representing the reaction of HSO−3
(a) as an acid with OH−
(b) as a base with HI
Solution
(a) HSO−3(aq)+OH−(aq)⇌SO2−3(aq)+H2O(l)
(b) HSO−3(aq)+HI(aq)⇌H2SO3(aq)+I−(aq)
Check Your Learning
Write separate equations representing the reaction of H2PO−4
(a) as a base with HBr
(b) as an acid with OH−
Answer:
(a) H2PO−4(aq)+HBr(aq)⇌H3PO4(aq)+Br−(aq)
(b) H2PO−4(aq)+OH−(aq)⇌HPO2−4(aq)+H2O(l)