Disproportionation and Water Treatment Flashcards
(30 cards)
What type of element undergoes disproportionation?
Halogens
What type of alkali solution do halogens react with?
Cold, dilute alkali solutions.
Is the halogen oxidised or reduced?
It is both oxidised and reduced.
What is meant by a disproportionation reaction?
This is where an element is both oxidised and reduced.
What two elements/compounds are used to make bleach?
Chlorine and sodium hydroxide.
What is the chemical name for bleach?
Sodium chlorate (1) solution.
What are 4 uses of sodium chlorate (1) solution?
Water treatment
Bleaching textiles
Bleaching paper
Toilets
What happens when you mix chlorine, iodine or bromine with water?
It undergoes a disproportionation reaction.
What is chorine used for?
It is used to kill bacteria in water.
What products are formed from mixing water?
Hydrochloric acid and chloric (1) acid.
Which chlorine containing acid ionises?
Aqueous chlorate (1) acid
What does aqueous chlorate (1) acid ionise to?
Chlorate (1) ions
What kills bacteria?
Chlorate (1) ions
Why is chlorine an important part of water treatment?
It kills disease-causing microorganisms and prevents reinfection further down the water supply.
It also prevents the growth of algae.
Why is it important that algae is not present in the water supply?
It can cause discolouration and can create bad tastes and smells.
What is the problem with chlorine gas?
It irritates the respiratory system if breathed in.
What is the problem with liquid chlorine?
If it gets in eyes or skin it can cause severe chemical burns.
What else does water contain?
A variety of hydrocarbons.
What products are formed from the reaction of chlorine with organic hydrocarbons?
Chlorinated hydrocarbons.
What is the problem with chlorinated hydrocarbons?
Some of them are carcinogenic.
If chlorine can create carcinogens, why is it used in water treatment?
The increased cancer risk is small especially compared to the risks of untreated water.
What are the two alternatives to chlorine in water treatment?
Ozone and UV light.
What is ozone good for?
It is good at killing microorganisms.
Why is ozone good at killing microorganisms?
It is a strong oxidising agent.
