Reactions of Halide Ions

Question 1

A disproportionation reaction is a reaction in which

Answer 1

the same species is both oxidised and reduced

Question 2

The reaction of chlorine with dilute alkali is an example of a

what happens in this reaction

Answer 2

example of a disproportionation reaction

In these reactions, the chlorine gets oxidised and reduced at the same time
Different reactions take place at different temperatures of the dilute alkali

Question 3

Chlorine in cold alkali (15 oC)
The reaction that takes place is:

Answer 3

Cl2(aq) + 2 NaOH (aq) > NaCl(aq) + NaClO + H20 (l)

Question 4

Chlorine in cold alkali (15 oC)
The reaction that takes place is:

ionic equation

Answer 4

Cl2 =0
one chlorine in NaCl reduced -1

other chlorine in NaClO is oxidised +1

other ions NaOH-

Question 5

Chlorine can be used to clean water and make it drinkable

The reaction of chlorine in water is a disproportionation reaction in which the chlorine gets both oxidised and reduced

This reaction is important in the purification of water for drinking and swimming pools

EQUATION

Answer 5

Cl2(g) + H20(l) > HCl(l) + HCLO

The disproportionation reaction of chlorine with water in which chlorine gets reduced to HCl and oxidised to HClO

Question 6

Chloric(I) acid (HClO des what to water

Answer 6

sterilises water by killing bacteria

Question 7

Chloric acid can further dissociate in water to form ………….

and equation

Answer 7

ClO- (aq):

HClO (aq) → H+ (aq) + ClO- (aq)

Question 8

ClO- (aq) also acts as a………… in the water

Answer 8

sterilising agent cleaning the water

Question 9

Chlorine is used in water treatment to kill bacteria

It has been used to treat drinking water and the water in swimming pools

The benefits to health of water treatment by chlorine by its killing of bacteria outweigh its risks of

Answer 9

outweigh its risks of toxic effects and possible risks from the formation of chlorinated hydrocarbons

Question 10

In shallow swimming pools chlorine is rapidly lost from the water, so the chlorine has to be topped up on a regular basis adding to cost
This is because it is more exposed to

Answer 10

sunlight
In sunlight, the following reaction occurs:

Question 11

In sunlight, the following reaction occurs:

Answer 11

2Cl2 (g) + 2H2O (l) → 4HCl (aq) + O2 (g)

Question 12

Adding chlorine to a water supply is an effective way to make the water safe to drink as it forms the sterilising agent HClO which in turn dissociates in water into another sterilising agent, ClO-(aq)