10.4- USES OF CHLORINE Flashcards
What is chlorine?
poisonous gas
Is chlorine soluble in water?
yes
Why is chlorine dissolved in water an essential part of our life? (hint- e.g. use)
in treatment of water for drinking and swimming pools
What type of reaction is it when chlorine reacts with water?
reversible reaction
What is formed when chlorine and water react together? (2)
chloric (I) acid, HClO
hydrochloric acid HCl
What is the equation for when chlorine and water react?
Cl2 (g) + H2O(l) = reversible HClO (aq) + HCl (aq)
What is disproportionation?
type of redox reaction, where the oxidation state of some atoms of same element increase and others decrease
What is the reaction between chlorine and water an example of?
disproportionation
Why is the reaction between chlorine and water an example of disproportionation?
number of one of the chlorine atoms increases from 0 to +1 and that of other decreases from 0 to -1
Example of when the reaction between chlorine and water take place?
when chlorine is used to purify water for drinking + swimming baths
Why is chlorine added to water to purify it?
prevent life-threatening diseases
What type of agent is chloric (I) acid?
oxidising agent
What does chloric (I) acid do?
kills bacteria by oxidation
What is chloric (I) acid also used as?
bleach
How do the other halogens react with water?
react similarly, but much more slowly going down the group
Does the same reaction between chlorine and water occur in sunlight?
no
What is the equation for the reaction between chlorine and water in sunlight?
2Cl2 (g) + 2H20 (l) = 4HCl (aq) + O2 (g)
What is the colour of chlorine?
pale green
What is the colour of HCl?
colourless
Why do shallow pools need frequent addition of chlorine in sunlight?
chlorine rapidly lost from pool water in sunlight
What is an alternative to the direct chlorination of swimming pools?
add solid sodium (or calcium) chlorate ().
What does the solid sodium (or calcium) chlorate do in the swimming pool?
dissolves in water
When the sodium (or calcium) chlorate dissolves in the water, what does it form?
chloric (I) acid, HClO (aq)
What is the reaction of sodium (or calcium) chlorate and water an example of? (hint- type of reaction)
reversible reaction
What is the equation for the reaction between sodium (or calcium) chlorate and water?
NaClO (s) + H2O =reversible Na+ (aq) + OH- (aq) + HClO (aq)
In alkaline solutions where does the position of equilibrium move for the reaction between sodium (or calcium) chlorate?
moves to left and HClO is removed as ClO- ions
What is done to prevent the position of equilibrium moving to the left in the reaction between sodium (or calcium) chlorate?
swimming pools need to kept slightly acidic
Why is the pH of swimming pools carefully monitored?
so water doesn’t get acidic enough to corrode metal components and affect swimmers
What is formed when chlorine and cold, dilute sodium hydroxide react?
form sodium chlorate (I), NaClO
What sort of agents is NaClO?
oxidisng agent
What is NaClO in?
active ingredient in household bleach
What is the reaction between chlorine and cold, dilute sodium hydroxide an example of?
disproportionation reaction
How do the other halogens behave when reacting with an alkali?
behave similarly
