IB Chemistry SL Reactivity 3.1.4 pH Scale

Practise converting between hydrogen-ion concentration and pH with logarithms. Use pH = −log₁₀[H⁺] and [H⁺] = 10⁻ᵖᴴ, retain appropriate significant figures and distinguish a…

Exam points

calculate solution pH from [H⁺] using the negative base-10 logarithm relationship
calculate [H⁺] from a stated pH using the inverse power-of-ten relationship
use concentration directly as [H⁺] only when complete ionisation and stoichiometry justify it

[Maximum number: 1]

Chlorine undergoes many reactions.

Chlorine gas reacts with water to produce hypochlorous acid and hydrochloric acid.

\mathrm{Cl}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{HClO}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq})

Calculate the concentration of $\mathrm{H}^{+}(\mathrm{aq})$ in a HClO(aq) solution with a pH=3.61.

« $\left[\mathrm{H}^{+}\right]=10^{-3.61}=$ » $2.5 \times 10^{-4}$ «mol dm ${ }^{-3}$ »

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3.1.4—pH scale question 1