to prepare ethene and examine its properties

balanced equation

C2H5OH -> C2H4 + H2O

type of reaction

dehydration

appearance of aluminium oxide

white powder

purpose of glass wool 

soak up ethanol, hold ethanol in place 

why is glass wool not heated directly

ethanol would vaprise too quickly - only small amount would convert to ethene 

what prevents suck back 

the delivery tube must be removed from water when heating is stopped to prevent tube from cracking 

purpose of aluminium oxide

dehydrating agent, catalyst

ethene flame

a luminous flame

unstaturated tests

bromine water, acidified potassium permangante

bromine water

changes from brown to colourless for an unsaturated compound

acidified potassium permangante

changes from purple to colourless in pressene of unsaturated compound

why does potassium permangante have to acidified

produces H+ ions (acts as a oxidising agent)

chemical equation of combustion ethene 

C2H4 + 3O2 - > 2CO2 + 2H20

chemical equation of addition of bromine 

C2H4 +2Br - 1,2, dibromoethane 

procedure

add 2-3cm of ethanol into test tube. add glass wool to bottom of test tube to absorb ethanol. add aluminium oxide halfway down the tube using a spatula. use bunsen burner set to blue flame and heat the aluminium oxide. as Al2O3 becomes hot, the heat reaches the ethanol which vaporises and is dehydrated to ethene. 5 test tubes of gas collected and stopper but in all once filled. delievery tube is taken out when heat is stopped. next perform tests on the test tubes but dont use the first one. observe its appearance colourless gas with a sweetish smell. remove stopper and place a lighted taper over the mouth flame should be a luminous, then test for unsaturation