IB Chemistry HL 3.1.2 Conjugate acid-base pairs Question Bank

Practise IB Chemistry HL 3.1.2 by applying conjugate acid-base pairs to exam-style questions.

Exam points

identify the relevant chemical structure, process or evidence
apply the correct chemical model or equation
evaluate the result using chemical reasoning and data

[Maximum number: 2]

Nitrous acid, $\mathrm{HNO}_{2}$ , is a weak acid which can be used to make acidic buffers.

A $1.00 \mathrm{~mol} \mathrm{dm}^{-3}$ solution of nitrous acid was prepared. This solution contains two conjugate acid-base pairs.

State the formulas of the conjugate acid and conjugate base in each pair.

Conjugate acid:
Conjugate base:
Conjugate acid:
Conjugate base:

（a）

（i）

conjugate acid $\mathrm{H}_{3} \mathrm{O}^{+}$ «（aq）» AND conjugate base $\mathrm{H}_{2} \mathrm{O}$ « $(\mathrm{l}) »$
conjugate acid $\mathrm{HNO}_{2}$ «（aq）» AND conjugate base $\mathrm{NO}_{2}{ }^{-}$ «（aq）»

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3.1.2—Conjugate acid-base pairs question 1