The uses of CFC’s
- CFC’s are compounds which contain chlorine, fluorine and carbon. There are several different CFC’s, each one having different boiling points. This versatility makes them useful in many products.
- CFC’s are very unreactive, have a low toxicity, and have a low flammability.
- Some uses of CFC’s:
What’s the problem with CFC’s?
- It was Thomas Midgeley, who in 1930 demonstrated a new refrigerant to the American Chemical Society.
- He inhaled his new refrigerant (CCl2 F2) and used it to blow out a candle; proving that it was non-toxic and had low flammability.
- Up to that time, Ammonia had been used as a refrigerant; however Ammonia was toxic and had an extremely unpleasant odour.
- Midgeley’s new compound was the perfect replacement for Ammonia (low boiling point, non-toxic, not flammable, and very unreactive).
- Unfortunately, he did his job too well; Dichlorodifluoromethane was too unreactive.
- CFC’s are so unreactive that they break down extremely slowly in the atmosphere; some CFC’s have a lifespan of up to 75 years!
- CFC’s can easily make it into the stratosphere, where the suns UV radiation is intense enough to dissociate CFC’s; producing Cl atoms.
- Cl atoms catalyse the destruction of the Ozone layer (see free radicals).
- As the effects of CFC’s became known, people began to demand their replacement.
- The chemical industry had to find compounds that would replace CFC’s and have no damaging effect on the ozone layer.
Useful books for revision:
Revise AS Chemistry for Salters (Written by experienced examiners and teachers of Salter's chemistry)
Revise AS Chemistry for Salters (OCR) (Salters Advanced Chemistry)