What is a disproportionation reaction?
Disproportionation is a redox reaction in which the same element is both oxidised and reduced.
The reaction of chlorine with water is an example of disproportionation: Cl2 + H2O ➔ HClO + HCl.
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Explain, with the use of an equation, the role of chlorine in water treatment.
Chlorine is used in water purification as a sterilising agent. When chlorine is added to water, chloric(I) acid (HClO) is formed which kills harmful bacteria.
Cl2(aq) + H2O(l) ➔ HClO(aq) + HCl(aq)
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Explain, with the use of an equation, the role of chlorine in the preparation of bleach.
Sodium chlorate(I) (NaClO) is an active ingredient in bleach. It is formed from the disproportionation reaction of chlorine with cold, dilute aqueous sodium hydroxide.
Cl2(aq) + 2NaOH(aq) ➔ NaClO(aq) + NaCl(aq) + H2O(l)
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What is the equation, including state symbols, for the reaction of chlorine with hot concentrated aqueous sodium hydroxide?
3Cl2(aq) + 6NaOH(aq) ➔ 5NaCl(aq) + NaClO3(aq) + 3H2O(l)
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