PAG 13.3 reaction of alkanes and alkenes

Question 1

method for experiment 1 combustion

Answer 1

1) place a piece of mineral wool onto a metal plate/ bottle lid
2) add a few drops of cyclohexane to the mineral wool and ignite it
3) observe the flame
4) repeat with cyclohexene

Question 2

results for experiment 1

Answer 2

cyclohexane- burns with a less sooty flame
cyclohexane- burns with a sooty flame

Question 3

method for experiment 2 reaction with bromine water

Answer 3

1) add 1 cm3 of each solution into the test tubes
2) add 1cm3 of bromine water to each test tube
3) place bung on test tube and shake to mix the reactants

Question 4

why do alkanes and alkenes flames look different when combusted?

Answer 4

alkenes have a high proportion of carbon in the compound making incomplete combustion more likely so a sootier flame/ more yellow flame burns