Chapter 13- Alkenes

Question 1

What is the general formula for an Alkene?

Answer 1

CnH2n

Question 2

What 2 bonds form a C=C bond?

Answer 2

sigma bonds and pi bonds

Question 3

What does the pi bond do?

Answer 3

Restricts rotation around the C=C bond

Question 4

What is the bond angle around the C=C bond?

Answer 4

120

Question 5

Are alkenes saturated or unsaturated?

Answer 5

unsaturated

Question 6

What 2 conditions are needed for E/Z isomerism?

Answer 6

A C=C double bond

Different groups attached to each carbon atom of the double bond

Question 7

What is the difference between E/Z isomerism and cis/trans isomerism?

Answer 7

In cis/trans isomerism, one of the attached groups on each carbon atom of the double bond must be the same.

Question 8

In 2 bromo-1chloropropene, using the Cahn- Ingold- Prelog system, which group has the higher priority?

Answer 8

Chlorine on the Carbon 1 and Brmeine of Carbon 2

Question 9

What is formed when an alkene is hydrogenised?

Answer 9

An alkane

Question 10

Write the chemical equation for C6H10 being hydrogenised.

Answer 10

C6H10+2H2 ->. C6H14

Question 11

Write the chemical equation for C4H4 reacting with Fluorine

Answer 11

C4H4+ 3F2 –> C4H4F6

Question 12

What 2 possible chemicals can you make when reacting but-2-ene with Hydrochloric acid.

Answer 12

2chloropropane

3choropropane

Question 13

What 2 possible chemicals can you make when reacting but-2-ene with Water.

Answer 13

propan-2-ol

propan-3-ol

Question 14

Define an electrophile

Answer 14

An electron pair acceptor

Question 15

What does a curly arrow with a double head mean when drawing the mechanism of electrophilic addition?

Answer 15

The movement of a pair of electrons

Question 16

Why does electrophilic addition work with Bromine as well as HBr?

Answer 16

Double bond is electron dense and so when bromine molecule comes near, the bromine atom nearest the double bond becomes positively charged

Question 17

Which product is the major product when propene and Hydrogen bromide react?

Answer 17

2- bromopropane

Question 18

Why does Markownikoff’s rule work?

Answer 18

The more groups attatched to the carbocation, the more stable the ion is, as the charge is more spread out. Addition of a hydrogen halide to an unsymmetrical alkene forms the major product via the most stable carbocation.

Question 19

Name the monomer that forms poly(chloroethane)

Answer 19

chloroethene (vinyl chloride)

Question 20

Give a use for poly(tetrafluoroethene)

Answer 20

Non- stick pans, cable insulation

Question 21

Why is using waste polymers as fuel a good idea?

Answer 21

As they are derived from petroleum or natural gas, they have a high stored energy value

Question 22

What are most biodegradable plastics made from?

Answer 22

Cellulose or Starch