6.8- Catalysts increase the rate of a reaction

Question 1

Reactions in the ozone layer

Answer 1

• Catalysts can take part in the reaction and regenerate later
• Occurs in the destruction of ozone by chlorofluorocarbons (CFCs)
• Ozone layer is a region in the stratosphere between 10km to 50km high will the greatest concentration at an altitude of 30km
  o Absorbs UV light (causes increased levels of skin cancers and eye problems)
• Main destroyer of ozone are CFCs
  o Non-flammable, non-toxic, cheap to manufacture, easy to store, and chemically stable
  o Used in aerosol cans, fire extinguishers, and asthma inhales
  o Used in foam insulation for furniture, refrigerant gas in fridges as ACS
  o Today alternative gases are used to avoid damaging the ozone layer
  o CFCs are broken apart from UB rays from the sun, releasing a free chlorine atom catalysts (destruction of ozone layer)
  o In this way, one chlorine atom from the original CFC can destroy up to 10000 ozone molecules

Question 2

Enzymes

Answer 2

• An enzyme is a catalyst made and used in living cells
• Enzymes play an important part in all cellular processes
• All reactions that occur inside a cell are catalysed by enzymes
• Many in our body to speed up chemical reactions
• E.g. digestive system to break down good
• Only work with specific reactants called substrates with certain reactions
• Region in which reactants bind to an enzyme is called an active site