Edexcel A-Level Chemistry A2 14.3 Define the Term Ph Questions

Practise defining pH as a logarithmic measure of hydrogen ion concentration for acid-base equilibrium work.

[Maximum number: 1]

Brønsted and Lowry defined acids and bases in terms of the transfer of a proton between two species.

When HA dissolves in water, the acidity of the resulting solution is measured using the pH scale. This depends on the number of moles of protons transferred.

Give the mathematical expression used to determine the value of pH .

An answer that makes reference to the following point:

- $\mathrm{pH}=-\log _{10}\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$

A description in words could take a number of forms

Accept $\mathrm{pH}=-\mathrm{lg}\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$

Accept $\mathrm{pH}=-\log _{10}\left[\mathrm{H}^{+}\right]$

Accept $\mathrm{pH}=-\log \left[\mathrm{H}^{+}\right]$

Accept $\mathrm{pH}=-\mathrm{lg}\left[\mathrm{H}^{+}\right]$

Award pH is the negative $\log$ to the base 10 of oxonium / hydronium / hydroxonium / hydrogen ion concentration

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