BRAINCAKEAcid-Base Indicators
An acid-base indicator is a weak acid which is one colour in its un-ionised form and another in its dissociated form.
HInd &rlhar H+ + Ind-
For methyl orange HInd is red and Ind- is yellow. For Litmus HLit is blue and Lit- is red. For phenolphthalein HInd is purple and Ind- is colourless.
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Key terms in this lesson
- equivalence point
- The point in a titration at which exactly enough of one solution has been added to react completely with the other.
- weak acid
- An acid that only partially dissociates into its ions in aqueous solution.
More in Acids, Bases and Buffers
- Calculating the pH of a Weak Acid
- The Ionic Product of Water Kw
- Calculating the pH of a Strong Base
- Buffer Solutions
- pH of a Buffer Solution
- Controlling the pH of Blood
- Titration Curves
- Standard Enthalpy of Neutralisation
All 15 lessons in Acids, Bases and Buffers · All OCR A-level Chemistry topics