10.4 Uses of chlorine Flashcards
What type of reaction is it when chlorine reacts with water
Reversible reaction
Redox reaction
Disproportionation
What products are formed from chlorine and water
Chloric (i) acid (HClO) ,
and hydrochloric acid (HCl)
Reaction between Cl2 and and H20
What’s happening?
Cl2(g) + H20(l) —> HClO(aq) + HCl(aq)
The oxidation number of one of the chlorine atoms increases from O to +1, and that of the other decreases from 0 to -1.
This type of redox reaction, where the oxidation state of some atoms of the same element increase, and others decrease is called a
Disproportionation reaction
When does the reaction between chlorine and water occur
Chlorine is used to purify water for drinking, and in swimming pools to prevent life threatening diseases .
Chloric acid is an oxidising agent and kills bacteria by oxidation, its also a bleach.
how do the halogens react with water down the group
They react similarly to chlorine but the reactivity decreases down the group
What is the reaction between water and chlorine in sunlight?
Why is it different to the original reaction
2Cl2(g) + 2H20(l) —> 4Hcl(aq) + O2
Chlorine is rapidly lost from pool water in sunlight, so shallow pools need frequent addition of chlorine.
What is an alternative to adding direct chlorine to pools
What do they dissolve to form
You can add sodium chlorate or calcium chlorate, both solid.
This dissolve to form chloric (i) acid, HClO(aq) in a reversible equation
What is the reversible reaction for adding sodium chlorate or calcium chlorate to pools
Why do pools need to be kept slightly acidic
NaClO(s) + H20(l) —> Na+(aq) + OH- +HClO(aq)
In alkaline solution, the equilibrium moves to the left and the HClO is removed as CLO- ions. To prevent this happening, swimming pools are kept slightly acidic.
Not too acidic as you don’t want to harm swimmers or corrode metal components
How does Chlorine react with alkali
eg sodium hydroxide
What type of reaction is it
What is the reaction
Reacts with cold, dilute sodium hydroxide to form sodium chlorate(i), NaClO
This is an oxidising agent and the active ingredient in household bleach.
This is also a disproportionation reaction:
Cl2 + 2NaOH —> NaClO(aq) + NaCl(aq) + H2O(l)
