Halogen Uses Flashcards
How do you make bleach ?
Mix chlorine with dilute sodium hydroxide
2NaOH (aq) + Cl2 -> NaClO + NaCl + H2O
What is the formula of household bleach ?
NaClO
Sodium chlorate (1)
What is the use of bleach ?
To kill bacteria
Specifically the ClO- (chlorate 1- ion ) that can kill the bacteria
What is the reaction to make bleach known as ?
A disproportionation reaction
What happens in a disproportionation reaction ?
1 substance is both oxidised and reduced simultaneously
Which atom has been both reduced and oxidised in the making of bleach ?
Both chlorine atoms have had a disproportionate share of bonded electrons
What is the use of chlorine ?
When reacted with water
It makes water safe to drink by killing bacteria
What is the chance of happening if water is not sterilised ?
A cholera epidemic can kill thousands of people
When you react chlorine with water, what is produced ?
It makes a ClO- ion which kills bacteria in water
What is the use of the ClO- ion other than killing bacteria ?
It prevents the growth of algae
Robing bad tastes , discolouration and smells
What is the chlorine with water reaction an example of ?
A disproportionation reaction
When the chlorine is both oxidised and reduced simultaneously
State the equation for the reaction of chlorine and water
Notes
Remember reversible reaction
What is the disadvantage of chlorine ?
Chlorine gas is a respiratory irritant
And as a liquid can cause chemical burns and irritation to the skin by itching
Can also make chemicals that cause cancer
Why is chlorine still used even after the serious disadvantages that it has ?
The benefits outweigh the risk
The disadvantages are only a very small chance
What must you make sure that chlorine is not exposed to?
Sunlight
