Hexane: remains orange (no colour change) Hexene: becomes colourless

Structure and Bonding

Both ethane and ethene are hydrocarbons, containing two carbon atoms each.

• Ethane has single C−C bonds, while ethene has a double C=C bond.
• Both have C−H bonds, but ethene has fewer hydrogen atoms due to the presence of the double bond.

Reactions

Both ethane and ethene combust in the presence of oxygen:

• In complete combustion, both produce water and carbon dioxide.
• In incomplete combustion, both can produce carbon monoxide and/or carbon.
• Ethene is generally more reactive than ethane, reacting with bromine water to decolourise it, while ethane does not.

Overall, while they share similarities as hydrocarbons, the presence of the double bond in ethene makes it more reactive than ethane.