3 Alkenes - Reactions

Question 1

Combustion of alkenes.

Answer 1

• alkenes = burn in air
• they release less energy per mole than alkanes
• alkenes are not used for fuel due to their high reactivity, this property makes them useful for other properties

Question 2

Example equation for the combustion of alkenes

Answer 2

C₂H₄ + 3O₂ → 2CO₂ + 2H₂O (COMPLETE)
C₂H₄ + 2O₂ → 2CO + 2H₂0 (INCOMPLETE)

Question 3

What are the electrophiles used in electrophilic addition? ((4))

Answer 3

HBr
Br₂
H₂SO₄
H₂O

Question 4

Which carbocation intermediates are the major product and why?

Answer 4

Tertiary carbocation intermediates are the major as they are the most stable carbocation intermediate. This is because the alkyl groups (C chain) donate electron density to the positive cation to stabilise it, this is called a positive inductive effect.