3.2.3.2 Uses of chlorine and chlorate

Question 1

How does chlorine react with water?
(equation)

Answer 1

Chlorine dissloves in water to form Cl2(aq)
and some chlorine reacts with water
Cl2(aq) + H2O(l) ⇌ HCl(aq) + HClO(aq)

Question 2

What is HOCl called?

Answer 2

hypochlorous acid

Question 3

What kind of reaction is the reaction of chlrorine with water

Answer 3

disproportionation reaction

Question 4

what is a disproportionation reaction and how come the reaction of chlorine and water is one?

Answer 4

one where a single substance is both oxidised and reduced.
This is a disproportionation reaction as the oxidation state of Cl changes from 0 to -1 and +1. (Chlorine is present in two of the products)

Question 5

Write an equation to show that hypochlorus acid is a weak acid

Answer 5

HClO(aq) + H2O(l) ⇌ H3O+ (aq) + ClO- (aq)

Question 6

What is the hypochlorite ion (ClO-) used for and why

Answer 6

is a powerful disinfectant and bleach – it kills bacteria

Question 7

What happens to the hypochlorite ion when it is exposed to sunlight

+ equation

Answer 7

The hypochlorite ion can decompose when exposed to sunlight.
2 ClO- (aq) –> 2Cl- (aq) + O2(g)

Question 8

Why do we add chlorine to water?

Answer 8

the benefits to health of water treatment by chlorine outweigh its toxic effects

Question 9

Write equation for the reaction of chlorine with **cold, dilute, aqueous **NaOH

Answer 9

Cl2(aq) + 2NaOH(aq) –> NaCl(aq) + NaClO(aq) + H2O(l)

Question 10

Uses of ClO- ion

Answer 10

powerful disinfectant-kills bacteria