[🧪] Hydrocarbons

Question 1

What are the two ways for dehydration of alcohols into alkenes?

Answer 1

1. dehydration using heated Al₂O₃ catalyst
2. dehydration using concentrated H₂SO₄

Production of alkenes

Question 2

Define

cracking

14 Hydrocarbons

Answer 2

the breaking down of large chain alkanes into smaller chain alkanes and alkenes

14 Hydrocarbons

Question 3

General equation for dehydration of alcohols to alkenes

Answer 3

CnH2n+1OH → CnH2n + H₂O

Question 4

Significance of alkenes’ π bonds

Answer 4

• it’s an area of high electron density
• pi electrons make the molecule more susceptible to attacks by e- deficient groups like electrophiles

Question 5

Define

electrophile

Answer 5

a species that is deficient in electrons

eg: positive ions (H+ in HCl)

Question 6

Define

electrophillic addition

Answer 6

the addition of an electrophile to a double bond

Question 7

3 methods of producing alkenes

Answer 7

• cracking of long chain hydrocarbons (Al₂O₃ catalyst and high temperature)
• dehydration of alcohols (heated Al₂O₃ catalyst / concentrated H₂SO₄)
• elimination of halogenoalkane (ethanollic NaOH and heat)

Question 8

Elimination reaction of halogenoalkane to form alkene

Answer 8

R—X + NaOH → Alkene + H₂O + NaX

Question 9

What is the mechanism for
halogenation of alkanes

Answer 9

free-radical substitution

Question 10

Define

functional group

Answer 10

an atom or a group of atoms in an organic molecule, which determines the physical and chemical properties of the molecule