Alkenes

Question 1

Define Alkenes and state their general Formula

Answer 1

Alkenes are hydrocarbon molecules containing a double bond as well as single covalent bonds, and known as unsaturated molecules. Each double bond contains 2 pairs of electrons
CnH2n

Question 2

Chemical Reactions of Alkenes

Answer 2

1. Addition reaction ( a reaction in which 2 or more molecules combine and no other molecule is formed ) C=C is unstable and tend to undergo addition reactions. C=C breaks to form 2 new single bonds
   unsaturated -> saturated
   - bromine (test to determine the presence of alkenes)
   Bromine decolourizes from brown to colourless
   - hydrogen gas (Nickel as catalyst at 150 C and Platinum catalyst at room temp)
   - steam, H2O [g] (at 300 C and 60 atm with the presence of conc phosphoric acid as catalyst)
2. Also combust in excess O2 to produce CO2 and H2O
3. Addition Polymerization
   conditions:
   i) 200 C, 1500 - 2000 atm, X catalyst
   ii) 60 - 100 C, 7 - 10 atm, Ziegler catalyst

Question 3

Alkenes properties

Answer 3

Insoluble in water but soluble in organic solvents

non conductor of electricity