13.3 Reactions of Alkenes

Question 1

Are alkenes more or less reactive than their corresponding alkanes?

Answer 1

more

Question 2

Explain the difference in reactivity of alkenes and alkanes:

Answer 2

alkenes MORE reactive

due to presence of PI BOND

which is WEAKER than sigma bonds

so requires less energy to break.

Question 3

What type of reaction do alkenes undergo?

Answer 3

addition

onto double bond

Question 4

What addition reactions do alkenes undergo?

Answer 4

HYDROGENATION

HALOGENATION

+ HALOGEN HALIDES

HYDRATION

Question 5

What is the general equation + conditions for HYDROGENATION of alkenes?

Answer 5

Alkene + Hydrogen ⟶ Alkane

▪ NICKEL catalyst
▪ 423K

Question 6

What is the general equation + conditions for HALOGENATION of alkenes?

Answer 6

Alkene + Halogen ⟶ Haloalkane

no specific conditions

Question 7

What is the general equation + conditions for adding HYDROGEN HALIDES to alkenes?

Answer 7

Alkene + Hydrogen Halides ⟶ Haloalkane

▪ room temperature

Question 8

What is the general equation + conditions for HYDRATION of alkenes?

Answer 8

Alkene + Steam ⟶ Alcohol

▪ phosphoric acid, H3PO4

Question 9

What is the test for unsaturation?

Answer 9

add BROMINE WATER, Br(aq) + H2O(l)

Solution turns from ORANGE ⟶ COLOURLESS.

(Br ions taken out of solution during addition reaction)

Question 10

Alkene + Hydrogen ⟶

Answer 10

Alkane

Question 11

Alkene + Halogen ⟶

Answer 11

Haloalkane (2 halogen atoms attached)

Question 12

Alkene + Hydrogen halide ⟶

Answer 12

Haloalkane (1 halogen atom attached)

Question 13

Alkene + Steam ⟶

Answer 13

Alcohol