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Acid Base Theories

C h e m g u i d e – q u e s t i o n s

ACID-BASE THEORIES

1. a) What is the Arrhenius definition of an acid? Give an example of an acid according to this theory.

b) What is the Arrhenius definition of a base? Give an example of a base according to this theory.

2. a) Give the definitions of an acid and a base on the Bronsted-Lowry theory.

b) Use the Bronsted-Lowry theory to explain the reactions which happen when

(i) hydrogen chloride gas dissolves in water;

(ii) hydrogen chloride gas and ammonia gas react;

(iii) ammonia gas reacts with a solution containing hydroxonium ions;

(iv) copper(II) oxide reacts with dilute sulphuric acid to give copper(II) sulphate and water.

3. a) When ethanoic acid is added to water, it reacts reversibly to give ethanoate ions and

hydroxonium ions.

COO

+ H

COOH + H

Use this reaction to explain the meaning of the terms conjugate acid and conjugate base, clearly

picking out the conjugate pairs.

b) Carbonate ions react slightly with water to give hydrogencarbonate ions and hydroxide ions.

HCO

+ OH

+ H

Identify the conjugate pairs in this reaction, in each case stating which is the conjugate acid and

which the conjugate base.

4. Use the following equations to help you to explain what is meant by the statement that “water is

amphoteric”.

+ H

+ OH

+ Cl

HCl + H

5. a) Define the terms Lewis acid and Lewis base.

b) Draw a dots-and-crosses diagram of a molecule of aluminium chloride, AlCl

, showing outer

electrons only. Would you expect this to behave as a Lewis acid, a Lewis base, or neither, or both?

Explain your answer.

Acid Base Theories