Module 4.2 end of topic test questions

Question 1

Cl
I
Cl —- C —- Cl
I
F

Is this molecule polar overall? Why?

Answer 1

Polar - F is more electronegative than Cl

Question 2

Explain the shape of a tetrahedral molecule

Answer 2

4 bonding pairs of electrons repel each other

Question 3

Why would using the haloalkane 1-chloropropane have a better atom economy that using 1-bromopropane when reacted with NaOH to form propan-1-ol?

Answer 3

The total relative molecular mass of the products would be less so atom economy will be greater

Question 4

Why is the hydrolysis of 1-iodobutane faster than the hydrolysis of 1-chlorobutane?

Answer 4

The C-I bond is weaker than the C-Cl bond so is easier to break

Question 5

Define the term radical

Answer 5

Species with an unpaired electron

Question 6

Write an equation for the breakdown of dichlorodifluoromethane to produce a chlorine radical

What type of bond fission occurs here?

Answer 6

CCl2F2 -> .Cl + .CClF2

Homolytic (since 2 radicals are formed)

Question 7

Why are CFCs broken down in the upper atmosphere instead of in the lower atmosphere?

Answer 7

Only UV in the upper atmosphere has enough energy to break the bonds

Question 8

Suggest why CFCs are still damaging the levels of ozone in the ozone layer, despite the fact that they have been banned

Answer 8

CFCs take a long time to reach the upper atmosphere

Question 9

Suggest why nitrogen monoxide is able to form during combustion

Answer 9

The heat makes the nitrogen and oxygen in the air to react

Question 10

HO. radicals are formed when an oxygen atom reacts with water. Write an equation for this initiation reaction

Answer 10

H2O + O2 -> 2HO.