Category Archives: 1.12 Acids and bases

Buffer action

Definition A buffer solution maintains an approximately constant pH, despite dilution or addition of small amounts of acid or base. Acidic buffer solutions contain a mixture of a weak acid (e.g. CH3COOH) and the salt of that weak acid (e.g. CH3COONa). Basic buffer solutions contain a mixture of a weak base (e.g. NH3(aq)) and the salt of that weak base (e.g. NH4Cl). Calculating the pH of a

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pH curves titrations and indicators

pH curves Understand typical pH curves for acid–base titrations in all combinations of weak and strong monoprotic acids and bases. Students should be able to: • sketch and explain the shapes of typical pH curves • use pH curves to select an appropriate indicator. A titration curve shows a graphical representation of the neutralisation reaction occurring between an acid and a base.

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Weak acids and bases Ka for weak acids

Weak acids and weak bases dissociate only slightly in aqueous solution. Ka is the dissociation constant for a weak acid. pKa = –log10 Ka Examples of calculating pH in weak acids IMPORTANTLY, there is no requirement to repeatedly state the proof for the derivation of the pH in a weak acid calculation. Full credit will be awarded to candidates if you simply

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Determining pH

  Determination of pH The term pH was introduced by Sørensen, a Danish chemist, as a way of measuring acidity during the fermentation process. pH = –log10[H+] where [ ] represents the concentration in mol dm-3 In conventional terminology, the log notation is taken as corresponding to log10 The concentration of hydrogen ions in aqueous solution covers a very wide range. Expressing

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Brønsted–Lowry acid–base equilibria in aqueous solution

Acids dissolve in water to give solutions of pH<7: acidity occurs as due to aqueous hydronium ions, H3O+ (aq). Basic solutions contain aqueous hydroxide ions, OH− (aq). Acids neutralise bases. A Brønsted-Lowry acid is a proton donor. A Brønsted-Lowry base is a proton acceptor. Conjugate acid-base pairs are related by the transfer of a proton. Hydrolysis of an acid or base produces a conjugate

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