3.2.3.2 Uses of chlorine and chlorate(I)

• Ionic equation between chlorine and cold dilute sodium hydroxide solution

  • Cl2 + 2HO– ---> OCl– + Cl– + H2O
• The reaction of chlorine with water to form chloride ions and chlorate(I) ions.

  • Cl2 + H2O ⇌ HClO + HCl
• The reaction of chlorine with water to form chloride ions and oxygen.

  • 2Cl2 + 2H2O -> O2 + 4HCl
• Appreciate that society assesses the advantages and disadvantages when deciding if chemicals should be added to water supplies.

  • The use of chlorine in water treatment.
  • to sterilise / disinfect water
  • to destroy / kill microorganisms / bacteria / microbes / pathogens
• Appreciate that the benefits to health of water treatment by chlorine outweigh its toxic effects.

  • used in (very) dilute concentrations / small amounts / low doses
  • a clear statement that once it has done its job, little of it remains
• The reaction of chlorine with cold, dilute, aqueous NaOH and uses of the solution formed.

  • Cl2 + 2NaOH -> NaClO + NaCl + H2O
  • Bleach / kills bacteria / bacteriacide / micro-organisms / microbes
  • Sodium chlorate (I) is formed
  • Oxidation state = +1