preparation of ethene

ethene is often referred to as...

industry's most important organic chemical because it is the starting material from which many other substances are made

dehydrating agent

A substance that can remove water from materials

dehydrating agent/catalyst for ethanol

aluminium oxide-Al2O3

dehydration is an example of what reaction

elimination

what should the flame not go near the end of the delivery tube

ethene is flammable

why is ethanol soaked in glass wool?

soaks up the ethanol and holds it in its place ar the end of the tube

appearance of Al2O3

white powder solid

chemical equation for ethene reaction

C2H5OH -\> C2H4 + H2O

function of aluminium oxide

catalyst and dehydrating agent

how does the aluminium oxide work

ethanol turns into a vapour as it passes over it and turns into ethene

why isn't ethanol heated directly?

it would turn into a vapor too quickly and would pass over the aluminium oxide too quickly without being converted to ethene

how many test tubes are collected?

5

Why is the first test tube discarded?

full of mostly displaced air

why is the delivery tube removed before turning off heat?

a suck back would occur - alcohol vapour inside the boiling tube cools and a vacuum is created and water is sucked back to fill the space

why is a suck back dangerous?

cold water could cause boiling tube to crack

physical properties of ethene

Colourless gas , sweetish smell , insoluble in water

why is ethene collected over water

non polar molecule

combustion

lighted taper produces a yellow luminous flame that is slightly smoky

Tests for unsaturation

addition of bromine water and acidified KMnO4

bromine water test

red to colourless - bromine adds across the c\=c

acidified KMnO4 test

purple to colourless

uses for ethene

used to ripen fruits