3.3.3 Halogenoalkanes

Question 1

what are the two propagation steps for ozone depletion?

Answer 1

• Cl• + O3 —> ClO•
• ClO• + O3 —> 2O2 + Cl•

Question 2

what does the ozone layer do?

Answer 2

absorb harmful UV radiation

Question 3

how are chlorine atoms formed in the upper atmosphere?

Answer 3

UV radiation causes C-Cl bonds in CFCs to break

Question 4

what are the conditions for elimination reactions?

Answer 4

• hot NaOH
• dissolved in ethanol

Question 5

what are the conditions for free radical substitution?

Answer 5

• Br2
• uv light to provide energy

Question 6

what’s the conditions for nucleophilic substitution to form an alcohol ?

Answer 6

• dilute NaOH
• warm

Question 7

what’s the conditions for nucleophilic substitution to form an amine?

Answer 7

• excess NH3
• dissolved in ethanol
• heat

Question 8

what’s the conditions for nucleophilic substitution to form a nitrile?

Answer 8

• KCN
• dissolved in ethanol

Question 9

how can CFC-11 contribute to global warming?

Answer 9

• has infrared radiation
• has polar bonds

Question 10

why is C-Cl polar and have diplole-dipole bonds?

Answer 10

• chlorine has a higher electronegativity
• chlorine becomes slightly negative and carbon becomes slightly positive

Question 11

how are vdw formed between two molecules?

Answer 11

• random movement of electrons
• induces a dipole in another molecule
• attraction between slightly positive and slightly negative in diff molecules

Question 12

what are some potential improvements for titration practicals (UPE)?

Answer 12

• dont use a measuring cylinder
  —> use a burette instead
• don’t use a glass beaker
  —> use a polystyrene cup instead
• use of low conc of silver nitrate
  —> use higher conc

Question 13

how would you set up a practical by weighing out solid?

Answer 13

• weigh out sample in boat
• transfer to conical flask and wash all sample
• dissolve sample in water
• add into volumetric flask with washings
• made up to mark in flask
• shake