Getting the Most From Reactants Flashcards
What are some considerations by industrial chemists when designing a reaction?
Availability, sustainability and cost of feedstocks Product yield Marketability of by-products Recycling reactants Energy requirements
What are the main principles of green chemistry?
- Waste prevention
- More energy-efficient with fewer steps and by-products to improve the atom economy
- Use of fewer hazardous and toxic chemicals
- Safer processes and chemicals
- Products that can be degraded in the environment
- Use of specific catalysts to reduce energy requirements
What is a common type of catalyst used in green chemistry?
Enzymes
How can the efficiency of a process be measured?
Calculating the percentage yield and atom economy.
What is the percentage yield formula?
% yield = (actual yield) / (theoretical yield) x 100
What is the atom economy formula?
Atom economy % = (mass of total desired product) / (total mass of reactants) x 100
What can improve the atom economy outwith the yield?
If the by-products can be used.
Do the % yield and atom economy affect each other?
No, if one is high it does not mean the other will be.
Why might the yield not be 100%?
- The reaction may not go to completion
- Side reactions that produce by-products
- Difficulty in purifying the product which can lead to loss of product
What do you call the reactant which is used up?
The limiting reactant
What is molar volume (Vm)?
The volume occupied by one mole of gas when measured at a given temperature or pressure.
When is the molar volume the same for any gas?
If it is measured at the same temperature and pressure.
What is the standard temperature and pressure?
s.t.p = 0 degrees C and 1 atmosphere pressure
What is the molar volume at standard temperature and pressure?
22.4 l mol-1
What is the molar volume at room temperature and pressure?
24.0 l mol-1; (20 degrees C and 1 atomsphere pressure)
