pH and Indicators (LC 2027) (Leaving Cert Chemistry): Flashcards

Substances that change colour based on pH of solution

Identify end point when acid and base neutralise

Weak acids

$\text{HIn} \rightleftharpoons \text{H}^+ + \text{In}^-$

Indicator molecule with hydrogen attached (acidic form)

Indicator molecule without hydrogen (basic form)

$3-5$

Red in acid, yellow in base

$5-8$

Red in acid, blue in base

$8-10$

Colourless in acid, pink in base

About 2 pH units

Mixture of several different indicators

Green