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org01 Ethyne (= acetylene), a hydrocarbon made of lime, coal and water
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Where natural gas and petrol
are not available, hydrocarbons can be
made from lime, coal and water. In a first step quicklime
and coal react to form calcium carbide, a brittle, very hard salt.
What
you need: Two infusion bottles 5
ml with wide mouthes, stopper, hammer, calcium carbide (CaC2),
water.
* Left: Prepare a
small piece of calcium carbide not bigger than a pea. Keep it in a tightly
closed 3-ml vial.
* Photo 2: Drop it
into a second bottle containing 1.5 ml of water.
ObservationsPhoto
3: A gas whith a bad smell is formed. The bottle gets hot. The piece
of calcium carbide disintegrates. A milky liquid can be seen.
* Photo 4: The gas
is burning with a sooty flame. * Right: A sediment and a colourless
solution are left.
Explanations:
Ethyne
(acetylen), lime water and slaked lime are formed by the chemical reaction
of calcium carbide and water:
CaC2(s) + 2 H2O(l) --------release of heat------------->
C2H2(g) + Ca(OH)2(l+s). .....