Chemistry Revision

1
Chemistry Revision

• Session 7

2
Equilibria

• Define the term dynamic equilibrium (3)
• Consider N2(g) 3H2(g)?Fe?2NH3 (g)
• ?H-100 kJ/Mol
• Explain what will be the effect on the yield of
  ammonia if I increase the pressure (3)
• Would changing concentrations or surface area
  increase yield of ammonia?
• What about increasing the temperature?

3
More on equilbria

• Even so a relatively high temperature is chosen
  is why (4 marks)
• What type of catalysis is this example?
• Use the following equilbria to explain what
  happens to the pH when CO2 dissolves
• CO2 (g) CO2 (aq)
• CO2 (aq) H2O (l) H (aq) HCO3 - (aq)

4
Global warming

• Explain why increasing carbon dioxide
  concentrations leads to increased global
  warming Make sure your answer includes the term
  infra-red!
• Name another greenhouse gas and explain a way it
  is made

5
CFCs

• Draw out the full structural formula of chloro,
  fluoro methane.
• Which bond would break first and explain how you
  made your choice.
• What environmental problem did CFCs cause, and
  why was this a problem?
• What type of radiation causes these bonds to
  break?

6
Ozone hole

• Suggest a catalytic cycle of the breakdown of
  ozone using chlorine atoms.
• Identify the catalyst and the intermediate.
• Write the overall equation

7
An answer

• Cl O3 ? ClO O2
• ClO O3 ? Cl 2O2
• 2O3 ? 3O2

8
Fission

• Consider bromoethane
• Done that? Good- now write equations showing the
  products when bromoethane undergoes heterolytic
  fission and homolytic fission, guessing which is
  which of course!

9

• Define the term radical
• Explain, using equations, how chlorine can
  chlorinate large amounts of ethane (forming
  chloroethane) (Free radical substitution
  mechanism)
• Is chloroethane a polar molecule or not? In your
  answer you should include the term
  electronegativity and perhaps a diagram?

10
Just a thought

• How much FANTASTIC chemistry are we covering
  AGAIN today?
• Isnt it marvellous?

11
Mechanism

• Explain the mechanism for the reaction between
  ammonia and ethanol. (5 marks)
• What type of mechanism is this (2 marks)
• State the reagents and conditions needed for this
  reaction (dont forget to learn this type of
  info!!)

12
Just a point

• Note your syllabus expects you to explain and
  use the terms nucleophile, hydrolysis,
  carbocation and substitution
• Finally name the following