Flashcards
Disproportionation and Water Treatment
Cards in this deck (19)
- 1What is disproportionation?When a single element is simultaneously oxidised and reduced
- 2The halogens are under disproportionation when they react with...Cold dilute alkali solutions (e.g. NaOH or KOH)
- 3Give the general symbol equation for the reaction between a halogen and dilute sodium hydroxideX₂ + 2NaOH --> NaXO + NaX + H₂O
- 4Give the general ionic equation for the reaction between a halogen and dilute sodium hydroxideX₂ + 2OH⁻ --> XO⁻ + X⁻ + H₂O
- 5TRUE OR FALSE: All of the halogens can exist in oxidation states other than 0 and -1FALSE
All of the halogens EXCEPT FLUORINE can exist in oxidation states other than 0 or -1 - 6Give the name and oxidation number of chlorine in ClO⁻Chlorate (I)
Oxidation number of +1 - 7What is the common use of sodium chlorate (I) solution?Household bleach
- 8How is bleach made? Give the balanced symbol equation for the reactionBy mixing chlorine gas with cold dilute aqueous sodium hydroxide
2NaOH + Cl₂ --> NaClO + NaCl + H₂O - 9In the reaction between sodium hydroxide and chlorine gas to form bleach, which element undergoes disproportionation?Chlorine is oxidised and reduced
- 10When you mix chlorine with water, it undergoes disproportionation. The products are hydrochloric acid and chloric (I) acid (also known as hypochlorous acid). Give the balanced symbol equation for this reactionCl₂ + H₂O ⇌ HCl + HClO
- 11Chloric (I) acid is formed when chlorine is mixed with water. Aqueous chloric (I) acid ionises to make chlorate (I) ions (also called hypochlorite ions). Give the balanced symbol equation for the ionisation of chloric (I) acidHClO + H₂O ⇌ ClO⁻ + H₃o⁺
- 12What is the use of chlorine (or a compound containing chlorate (I) ions)?Chlorate (I) ions kill bacteria. So adding chlorine (or a compound containing chlorate (I) ions) to water can make it safe to drink or swim in.
Chlorine kills disease-causing microorganisms. It also prevents the growth of algae, eliminating bad tastes and smells, and removes discolouration caused by organic compounds. - 13What are the risks of using chlorine to treat water?Chlorine gas is toxic - it irritates the respiratory system
Liquid chlorine on the skin or eyes causes severe chemical burns
Water contains a variety of organic compounds (e.g. from the decomposition of plants); chlorine reacts with these compounds to form chlorinated hydrocarbons and many of these are carcinogenic. HOWEVER! This increased cancer risk is small compared to the risks from untreated water (e.g. cholera epidemic) - 14Why might people object to having their water chlorinated in terms of ethical considerations?People don't get a choice about having their water chlorinated and some people object to this as forced 'mass medication'
- 15What are the two alternatives to chlorine in water treatment?Ozone (O₃)
Ultraviolet light (UV) - 16How might ozone be used for water treatment?Ozone is a strong oxidising agent, which makes it great at killing microorganisms
- 17What are the disadvantages of using ozone for water treatment?It's expensive to produce
Short half-life means that treatment isn't permanent - 18How might UV be used for water treatment?UV kills microorganisms by damaging their DNA
- 19What are the disadvantages of using UV for water treatment?It is ineffective in cloudy water
Short half-life in water means that treatment isn't permanent
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- User has deleted their subject information Flashcards on Disproportionation and Water Treatment, created by Deleted user on 05/03/2018.
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- Deleted user · Mar 2018
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- Mar 5, 2018
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- Created by Yinka F · Mar 4, 2018
- Copied by Yinka F · Mar 5, 2018
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