BRAINCAKEAcids, Bases and Buffers
Revision notes for Acids, Bases and Buffers in OCR Chemistry A (H432). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- Acids and BasesWhen an acid is added to water it dissociates into H+ ions and anions.
- Conjugate Acid-Base PairsAn acid-base pair is a set of two species that transform into each other by the gain or loss of a proton.
- Strong and Weak Acids and BasesA strong acid completely dissociates into its ions in aqueous solution.
- The Acid Dissociation Constant KaA weak acid has the following equilibrium in aqueous solution: HA (aq) &rlhar H+(aq) + A-(aq) The expression for the acid dissociation constant is…
- pHThe pH scale is a convenient way of measuring the hydrogen ion concentration.
- Calculating the pH of a Strong AcidStrong acids completely dissociate in aqueous solution.
- Calculating the pH of a Weak AcidWeak acids only partially dissociate in aqueous solution.
- The Ionic Product of Water KwPure water ionises into H+(aq) and OH-(aq) ions to a very tiny extent.
- Calculating the pH of a Strong BaseThe strength of a base is its ability to dissociate and generate OH- ions in solution.
- Buffer SolutionsA buffer solution resists changes in pH when small amounts of acid or alkali are added.
- pH of a Buffer SolutionTo find the pH of any solution, you need to determine the hydrogen ions concentration.
- Controlling the pH of BloodHuman blood plasma has to be between 7.35 and 7.45.
- Titration CurvesIn a titration, you measure the volume of the solution in the burette that is needed to react exactly with the solution in the conical flask.
- Acid-Base IndicatorsAn acid-base indicator is a weak acid which is one colour in its un-ionised form and another in its dissociated form.
- Standard Enthalpy of NeutralisationThe standard enthalpy of neutralisation ΔHneut is the enthalpy change when an acid and a base react to form 1 mole of water under standard…