Halogenoalkanes practise questions

Question 1

State the benefit to life on Earth of ozone in the upper atmosphere.

Answer 1

Absorbs (harmful) ultraviolet / uv (light / radiation)

Question 2

A typical refrigerator contained 0.50 kg of CFC-11 (Mr = 137.5).
One molecule of CFC-11 causes the destruction of approximately 100 000
molecules of ozone.
Use these data to estimate the number of molecules of ozone that can be
destroyed by 0.50 kg of CFC-11
Give your answer in standard form.
The Avogadro constant, L = 6.022 × 1023 mol–1

Answer 2

amount of CFC-11 = 500/137.5 ( = 3.64) mol
molecules of O3 = 3.64 x 100,000 x 6.022 x 1023 = 2.19 x 10^29

Question 3

Suggest one reason why the use of CFCs was not restricted until several
years after Rowland and Molina published their research.

Answer 3

One of these reasons:
* lack of evidence that ozone was being depleted
* lack of alternatives to CFCs
* commercial interest to continue to use CFCs
* hard to obtain international agreement

Question 4

CFC-11 is a greenhouse gas that can contribute to global warming.
State and explain how CFC-11 is able to contribute to global warming

Answer 4

M1 absorbs infrared radiation

M2 molecule has polar bonds

Question 5

Give the IUPAC name of CH3CH2CN(triple bond CN)

Answer 5

Propanenitrile

Question 6

Q6.
Which compound can react with ammonia to produce propylamine?
A CH3CH═CH2
B CH3CH2CH2OH
C CH3CH2CH2Br
D CH3CH2CH3

Answer 6

C
CH3CH2CH2B

Question 7

Which compound could not be produced by reacting 2-bromo-3-methylbutane
with sodium hydroxide?
A 2-methylbut-1-ene
B 3-methylbut-1-ene
C 2-methylbut-2-ene
D 3-methylbutan-2-ol

Answer 7

Q7.
A
2-methylbut-1-ene

Question 8

Explain why D reacts more quickly than A with dilute aqueous sodium
hydroxide at the same temperature. (D= C-Br, A=C-Cl)

Answer 8

C–Br is weaker than C–Cl or
C–Br has lower bond enthalpy than C–Cl or
C–Br breaks more easily C–Cl