A1: Haloalkanes

Question 1

Rate of reaction of C-X bonds

Answer 1

Rate increases from C-F (unreactive) to C-I

Question 2

Bond enthalpy pattern of C-X bonds

Answer 2

bond enthalpy increases from C-I to C-F

Question 3

Nitrogen oxide catalysing ozone breakdown: initiation

Answer 3

NO. radicals are formed naturally during lightning strikes and by aircraft travel

Question 4

Nitrogen oxide catalysing ozone breakdown: propagation

Answer 4

1) NO.+O3 –> NO2. + O2
2) NO2.+ O –> NO. + O2

Question 5

Nitrogen oxide catalysing ozone breakdown: overall equation

Answer 5

O3 + O –> 2O2

Question 6

Breakdown of Ozone by CF2Cl2: photodissociation

Answer 6

with uv radiation
CF2Cl2 –> CF2Cl. + Cl.

Question 7

Breakdown of Ozone by CF2Cl2: propagation

Answer 7

1) Cl. + O3 –> ClO. + O2
2) ClO. + O –> Cl. + O2

Question 8

Breakdown of ozone by CF2Cl2 overall equation

Answer 8

O3 + O –> “O2

Question 9

Experiment: measuring the rate of hydrolysis of primary haloalkanes

Answer 9

1) In three test tubes, add 1cm^3 of ethanol and then two drops of 1-chloro/bromo/iodobutane
2) Stand in a sixty degree c waterbath
3) Place test tube with 0.1moldm-3 AgNO3 in the water bath
4) add 1cm3 of the silver nitrate to each test tube and record time for ppt to form

Question 10

Observations from the hydrolysis experiment (haloalkanes)

Answer 10

1-chlorobutane = white ppt, formed very slowly
2-bromobutane = cream ppt, medium time
3-iodobutane = yellow ppt forms rapidly