Chapter 11 Chemical Changes

Question 1

Uses for hydrochloric acid

Answer 1

Remove impurities such as rust and scale from metals and aluminium alloys

Question 2

Uses for nitric acid

Answer 2

Used to make explosives and fertilisers

Question 3

Uses for sulfuric acid

Answer 3

Used in car batteries, manufacturing of detergents and fertilisers

Question 4

Uses for phosphoric acid

Answer 4

Used in food and beverages to give them a sour taste

Question 5

Uses for ethanoic acid

Answer 5

Used in vinegar as a food preservative and flavour enhancer

Question 6

Physical properties of acids

Answer 6

sour, corrosive, turns litmus paper blue to red, conduct electricity

Question 7

dilute acid + reactive metal

Answer 7

salt + hydrogen gas

Question 8

dilute acid + metal carbonate

Answer 8

salt + carbon dioxide + water

Question 9

acid + alkali

Answer 9

salt + water (neutralisation)

Question 10

applications of neutralisation

Answer 10

1. hair conditioners contain a mild acid to neutralise the alkaline shampoo thus making our hair feel smooth and easy to manage
2. powdered calcium hydroxide can be added to neutralise acidic soil so plants can grow better

Question 11

uses of sodium hydroxide

Answer 11

make soap

Question 12

uses of potassium hydroxide

Answer 12

make soaps

Question 13

uses of calcium hydroxide

Answer 13

neutralise acidic soil

Question 14

uses of ammonia solution

Answer 14

make fertilisers

Question 15

properties of alkali

Answer 15

bitter taste, soapy feeling, turns red litmus paper blue

Question 16

aqueous alkali + ammonium salt

Answer 16

salt + water + ammonia gas