Alkanes & Alkenes

Question 1

Combustion of Alkanes

Answer 1

Both burn in oxygen/air to:
Complete: give CO2 & H2O
Incomplete: give carbon monoxide/carbon (soot)

Question 2

Substitution Reaction with Alkanes

Answer 2

Alkanes react with halogens in the presence of ultraviolet radiation. A H2 atom in the alkane is replaced by a halogen atom.

Question 3

Addition Reaction with Alkenes

Answer 3

Part of the double bond breaks to become a single bond and the electrons are used to join other atoms onto the two carbon atoms.

You can also use alkenes in combustion reactions, which have the same products as alkane reactions. However, alkenes are too useful to waste burning them.

Question 4

Reaction of Alkenes with Bromine

Answer 4

1. Shake unknown organic compound with bromine water.
2. If the orange bromine water is decolourised, the compound contains a carbon-carbon double bond.