Uses of sodium and chlorine
Both products of the Downs cell are useful.
Uses of sodium
In sodium vapour lamps, which give a yellow light.
Liquid sodium is used as a coolant in the nuclear reactors of nuclear power stations.
Needed for experimental work in laboratories.
Uses of chlorine
Bubbled through drinking water to kill bacteria.
Bleaching (removing colour from) paper pulp and cloth.
Reacted with hydrogen to make hydrochloric acid.
Used to make plastics such as PVC.
Why each property suits its use
Sodium is a metal that melts at under 100 °C and stays liquid over a wide range of temperature, and like all metals it carries heat well — so liquid sodium can carry heat out of a reactor core. When electricity passes through its vapour, it glows the bright yellow you see in some street lamps. Chlorine is a very reactive, poisonous gas. In tiny amounts that reactivity is what kills bacteria in drinking water and breaks down coloured compounds in bleaching. Joined to hydrogen it gives hydrogen chloride, which dissolves to hydrochloric acid, and joined into carbon compounds it gives PVC, the plastic of water pipes.
Chlorine is poisonous
The amount of chlorine used to treat drinking water is very small. The gas itself is poisonous and must never be made or breathed outside a fume cupboard.
Sodium and chlorine at work
Sodium: vapour lamps, reactor coolant, laboratories. Chlorine: disinfecting water, bleaching, hydrochloric acid, PVC.