Acids & Bases 5.1.3 OCR A Level Chemistry H432

Unit Outcomes: Learners should be able to demonstrate and apply their knowledge and understanding of: Brønsted–Lowry acids and bases (a) (i) a Brønsted–Lowry acid as a species that donates a proton and a Brønsted–Lowry base as a species that accepts a proton (see also 2.1.4 Acids) (ii) use of the term conjugate acid–base pairs (iii) monobasic, dibasic and tribasic acids (b) the role of H+ in the reactions of acids with metals and bases (including carbonates, metal oxides and alkalis), using ionic equations (see also 2.1.4 c, 2.1.5 e) (c) (i) the acid dissociation constant, Ka, for the extent of acid dissociation (see also 2.1.4 b) (ii) the relationship between Ka and pKa pH and [H+(aq)] (d) use of the expression for pH as: pH = –log[H+] [H+] = 10–pH (e) use of the expression for the ionic product of water, Kw (f) calculations of pH, or related quantities, for: (i) strong monobasic acids (ii) strong bases, using Kw (g) calculations of pH, Ka or related quantities, for a weak monobasic acid using approximations (h) limitations of using approximations to Ka related calculations for ‘stronger’ weak acids