haloalkanes

Question 1

nucleophile

Answer 1

electron pair donor

Question 2

explain how chlorine atoms are formed from chlorine-containing organic compounds in the upper atmosphere

explain, with the aid of equations, how Cl atoms act as a catalyst in the decomposition of ozone into oxygen

(6)

Answer 2

UV light

C-Cl bond breakage

Cl* + O3 –> ClO* + O2
ClO* + O3 –> Cl* + 2O2

Cl* not used up

Cl* lowers activation energy

Question 3

why is desflurane considered to be a more environmentally acceptable anaesthetic than halothane

(2)

Answer 3

Halothane contains C-Cl bond

Desflurane contains fluorine as the only halogen so does not react with ozone layer

Question 4

NO catalyses the decomposition of ozone into oxygen. Write the overall equation for this decomposition

(1)

Answer 4

2O3 –> 3O2

Question 5

In the upper atmosphere, it is more likely for CBrF3 to produce Br atoms than it is for CClF3 to produce Cl atoms. Suggest one reason for this

Answer 5

C-Cl has a higher bond enthalpy than C-Br (or stronger than..)

Question 6

Le Chatelier’s principle

Answer 6

If any factor is changed which affects equilibrium, the equilibrium will shift to oppose the change

Question 7

Explain why pentane is a more environmentally acceptable refrigerant than CFCs

Answer 7

pentane does not contain chlorine (C-Cl bond)

Question 8

write 2 equations to show how Cl free radical is involved as a catalyst in them decomposition of ozone

Answer 8

Cl* + O3 –> ClO* + O2

ClO* + O3 —> Cl* + 2O2