The ozone layer and rates of substitution

Question 1

What is a CFS

Answer 1

Chlorofluorocarbons are haloalkanes. Used as a coolant in refrigerators

Question 2

Ozone Breakdown Mechansim

Answer 2

Initiation: CCl3F —> Cl. + .CCl2F
Propagation: Cl. + O3 —> ClO. + O2
Clo. + O3 —-> 2O2 + Cl
Cl. Is regenerated in the final propagation step and causes a chain reaction in the decomposition of ozone. Cl behaves as a catalyst.

Question 3

Method for rates of hydrolysis

Answer 3

1. Place a measured sample of each halogenoalkane into separate test tubes and place into a water bath at 500`c
2. Into another test tube place a solution of ethanol, water and aqueous silver nitrate and place in the same water bath.
3. Once at equal temperature add equal volumes of the ethanol mixture and haloalkane solutions together
4. Time how long it takes for each precipitate to form.

Question 4

Results

Answer 4

Chloropropane- white AgCl
Bromopropane- cream AgBr
Iodopropane- Yellow, Agl

Question 5

Bond enthalpy

Answer 5

As the bond enthalpy decreases it is easier to break the C-Halogen bond. The stronger the bond the harder it is to break and the stronger it is to break and the slower the rate of reaction will be as more energy required to break it. The weaker the bond the faster the rate. C-I is the weakest. C-Cl is the strongest