Electrolysis of water. Image credit dordt.edu

Electrolysis of water. Image credit dordt.edu

ZIMSEC O Level Combined Science Notes: Electrolysis of water to produce gases

  • Hydrogen gas is mainly produced using electrolysis of water
  • In Zimbabwe this is done at the Sable Chemicals plant in Kwekwe
  • Water is drawn from the Sebakwe River
  • Electricity is taken from the ZESA grid and Sable has its own substation
  • Pure water does not conduct electiricty very well as a result
  • Potassium hydroxide (an alkali) or sulphuric acid is added to the water to improve its conductivity
  • Carbon electrodes are used to carry current into and out of the electrolyte
  • The size/chemical composition do not change during the process unlike in electroplating
  • During the process water is broken into the elements
  • Hydrogen and Oxygen
  • The hydrogen comes from the cathode (negative) and
  • The oxygen comes from the anode (positive)
  • The Hydrogen and Oyxgen are produced in a ratio of 2:1
  • The oxygen is then carried in pipes to ZISCO where it is used in the manufacture of steel
  • The hydrogen is used in the manufacture of ammonia at Sable industries and the manufacture of margarine

To access more topics go to the Combined Science Notes page.