TXTBK: Elements from the sea

Question 1

ES) a)

What is the formula for atom economy?

Answer 1

% atom economy = M_r of desired product / M_r of all products x 100%

Question 2

ES) a)

How is atom economy considered in the chemical industry?

Answer 2

• reactions with high atom economies are better than reactions with low atom economies, as they produce less waste, making them cheaper and more environmentally friendly

Question 3

ES) a)

Why doesn’t the chemical industry rely only on atom economy when reducing waste and trying to be the most cost-effective?

Answer 3

• Reaction with high atom economy but a low percentage yield may not be as cost-effective as a reaction with moderate atom economy and a moderate percentage yield
• Also have to consider the reactions conditions
  
  • high temperatures and pressures = expensive to maintain

Question 4

ES) a)

What does atom economy measure?

Answer 4

• measure of the efficiency of a reaction
  
  • by measuring the proportion of reactant atoms that become part of the desired product

Question 5

ES) a)

How is atom economy different to percentage yield?

Answer 5

• percentage yield - shows how wasteful a process is
  
  • based on how much of the product is lost due to reactions not completing or losses in collection and purification etc.
• percentage yield - doesnt measure how wasteful reaction is itself
• reaction with 100% yield could still be very wasteful if a lot of the atoms from the reactants become by-products rather than the desired product