Carboxylic Acids and Esters Basic Reactions

Question 1

Give the word and symbol equations for Magnesium metal reacting with aqueous Ethanoic Acid.

Answer 1

Magnesium + Ethanoic Acid —-> Magnesium Ethanoate +
Hydrogen Gas

Mg(s) + 2CH3COOH(aq) —> (CH3COO)2Mg(aq) + H2(g)

Question 2

Give the word and symbol equations for Ethanoic Acid reacting with Potassium Hydroxide. State the two types of species that react in this way with carboxylic acids.

Answer 2

Ethanoic Acid + Potassium Hydroxide —> Potassium
Ethanoate + Water

CH3COOH(aq) +KOH(aq) —> CH3COOK(aq) + H2O(L)

Reaction occurs with alkalis and basic metal oxides.

Question 3

Give the word and symbol equations for Ethanoic Acid reacting with Calcium Carbonate.

Answer 3

Ethanoic Acid + Calcium Carbonate —> Calcium Ethanoate + Water + Carbon Dioxide Gas

2CH3COOH(aq) + CaCO3(s) —> (CH3COO)2Ca(aq) +H2O(L) +CO2(g)

Question 4

Give the word and symbol equations for the two methods used to prepare an ester. State any conditions for each.

Answer 4

1) Carboxylic Acid + Alcohol —> Ester + Water
CH3COOH + CH3CH2OH —> CH3COOCH2CH3 +H2O

Conditions: Glacial ethanoic acid, heat, conc. H2SO4 catalyst

2) Acid Anhydride + Alcohol —> Ester + Carboxylic Acid
(CH3CO)2O +CH3CH2OH —> CH3COOCH2CH3 +
CH3COOH

Question 5

What are the two methods of hydrolysis for esters?

Answer 5

Acid and alkaline hydrolysis.

Question 6

What is the advantage of using an acid anhydride and alcohol to prepare an ester over using a carboxylic acid and alcohol?

Answer 6

Acid anhydride route goes to completion/does not produce equilibrium mixture.

Question 7

What is the advantage of alkaline hydrolysis over acid hydrolysis of an ester?

Answer 7

Reaction goes to completion/does not produce equilibrium mixture.

Question 8

What are the conditions necessary for the hydrolysis of an ester, using an acid or alkali?

Answer 8

Heating under reflux.

Question 9

What does acid hydrolysis of an ester produce?

Answer 9

A carboxylic acid and an alcohol.

Question 10

What does alkaline hydrolysis of an ester produce?

Answer 10

An alcohol and a salt of the carboxylic acid.

Question 11

State the product of alkaline hydrolysis of a Benzoate ester with NaOH. Go on to describe and explain any observations that would be made when resulting mixture is acidified.

Answer 11

Produces aqueous solution of Sodium Benzoate. Acidifying this solution produces a white precipitate of Benzoic Acid. This precipitation occurs due to the non polar nature of the benzene ring, meaning Benzoic Acid is only sparingly soluble in water.