CO₂

a poison that must be removed

Design an air filtering system for a submarine? This filter must remove odours and carbon dioxide from the air. Conduct some experiments to see how best to remove odours.

Try using common household baking powder and discuss your results.

Indicate where the air is channelled and what reactions take place.

For long space voyages discuss how best to provide oxygen and remove carbon dioxide?

Carbon dioxide is toxic to the astronauts. If its concentration is allowed to increase it will be fatal. The Orbiter has special air filters containing lithium hydroxide. The air is passed through the filters and any carbon dioxide present reacts with the lithium hydroxide to produce a harmless solid substance called lithium carbonate. Just like the movie above calcium hydroxide (lime water) works in a similar way to lithium hydroxide. As carbon dioxide is bubbled through lime water solid calcium carbonate is formed. Calcium carbonate is non toxic, in fact it is the substance the normal chalk is made up of.

The filtered air has no carbon dioxide, all the carbon dioxide has reacted to form lithium carbonate. Lithium carbonate stays in the filters as a solid substance.

When CO₂ is bubbled through water containing calcium hydroxide (lime water) a solid white substance is formed. This white solid has the chemical name calcium carbonate.