alkenes and their reactions

• what's the general formula for alkenes?

  CnH2n
• alkenes have double bonds between 2 of the carbon atoms (c=c)
• what's the first 4 alkenes?

  Ethene, propene, butene, pentene
• alkenes burn with a smoky flame
• alkenes undergo incomplete combustion
• what is the equation for incomplete combustion?

  alkene + oxygen -> carbon +carbon monoxide +carbon dioxide + water
• alkenes react with halogens and form saturated molecules with c=c carbons each bonded to a halogen atom
• alkenes turn bromine water colourless
• steam can react with alkenes to form alcohols