CARBOXYLIC ACIDS [dchemlc]

what is the functional group of carboxylic acids?

• 
• 
• 
• 

Answer explanation

carboxylic acids all contain the functional group -COOH.

what is the carboxylic acid present in vinegar?

• ethanoic acid

• methanoic acid

• propanoic acid

• butanoic acid

Answer explanation

The most familiar one is ethanoic acid (old name acetic acid). Vinegar is an aqueous solution containing ethanoic acid.

how is propanoic acid produced?

• by the oxidation of propanol

• by the oxidation of ethanol

• by the oxidation of propene

• by the oxidation of propane

Answer explanation

Carboxylic acids are formed by oxidation of the corresponding alcohols.

name the given carboxylic acid

(a)  

if a blue litmus paper was dipped in a carboxylic acid, what would be the colour produced?

• red

• blue

• purple

• green

Answer explanation

Ethanoic acid and the other carboxylic acids are weak acids with a pH of about 3-5, depending on the concentration of the solution. They will turn blue litmus paper red, and react with all the things you expect acids to react with.

what is the pH range of carboxylic acids?

• 3 - 5

• 1 - 3

• 5 - 7

• 7 - 9

Answer explanation

Ethanoic acid and the other carboxylic acids are weak acids with a pH of about 3-5.

dilute ethanoic acid reacts with magnesium with a lot of fizzing to produce

• magnesium ethanoate

• hydrogen

• oxygen

• carbon dioxide

• magnesium ethanoic acid

Answer explanation

dilute ethanoic acid reacts with magnesium with a lot of fizzing to produce a salt and hydrogen. The salt formed is magnesium ethanoate, which is soluble in water and so you get a colourless solution:

what is the expected observation of the given reaction?

• a colourless solution

• a white precipitate

• a white solution

• a pink brown precipitate

Answer explanation

dilute ethanoic acid reacts with magnesium with a lot of fizzing to produce a salt and hydrogen. The salt formed is magnesium ethanoate, which is soluble in water and so you get a colourless solution:

what will be produced when sodium carbonate is added to ethanoic acid?

• sodium ethanoate

• carbon dioxide

• water

• hydrogen

• sodium hydroxide

Answer explanation

Carbonates react with acids to give a salt, carbon dioxide and water.

what is the expected observation of the given reaction?

• a colourless solution

• a white precipitate

• a white solution

• a pink brown precipitate

Answer explanation

Ethanoic acid and calcium carbonate produces lots of fizzing and a colourless solution containing calcium ethanoate.