Bronsted-Lowry Definition of Acid – Base behaviour A Bronsted-Lowry acid is defined as a substance that can donate a proton. A Bronsted-Lowry base is defined as a substance that can accept a proton. HCl (g) + H2O (l) H3O+ (aq) + Cl- (aq) Acid 1 base 2 Acid 2 Base 1 Each acid is linked to a conjugate base on the other side of the equation. HNO3 + HNO2 ⇌ NO3 – + H2NO2+ Acid 1 Base 2 Base 1 Acid 2 HCOOH + CH3 (CH2 )2COOH ⇌ HCOO– + CH3 (CH2 )2COOH2+ Acid 1 Base 2 Base 1 Acid 2 In these reactions the substance with bigger Ka will act as the acid The acidic role of H+ in the reactions of acids with metals, carbonates, bases and alkalis acid + metal salt + hydrogen 2CH3CH2CO2H + Mg (CH3CH2COO)2Mg + H2 acid + alkali (NaOH) salt + water 2HNO2 + Ca(OH)2 Ca(NO2 )2 + 2H2O acid + carbonate (Na2CO3 ) salt + water + CO2 2CH3CO2H + Na2CO3 2CH3CO2 -Na+ + H2O + CO2 2H+ + Mg Mg2+ + H2 Ionic Equations H+ + OH– H2O 2H+ + CO3 2– H2O + CO2
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5.1.3 Acids, bases and buffers
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 Learners should be able to identify acid–base pairs in equations for acid–base equilibria. HSW1,7 Development of different models over time to explain acid–base behaviour. (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)
5.1.3 acids bases and buffers Page 1
Oxford Textbook Pages : 310 - 314
CGP Revision Guide Pages : 134 - 135