IMPLICATIONS OF CHEMICAL SYNTHESIS AND DESIGN Flashcards
List the five factors to consider when designing a chemical synthesis process
- availability of reagents
- reaction conditions
- yield and purity
- industrial uses (eg. pharmaceuticals, cosmetics, fuels, cleaning products etc)
- environmental, social and economic issues
why is the availability of reactants important
Reactants are what drives a forward reaction. The quantity of moles of product formed is limited by the moles of reactants available by mole reaction. once all moles of reactants are formed no more products can be produced.
Why is a high level of reactants important in equilibrium reactions?
As predicted by Le Chatelier’s Principal, a high availability of reactants shifts the equilibrium position to the right and drives the reaction forward to produce more moles of product.
Since availability of reactants are important give an example of how this is demonstrated in industry
–> Oil refineries are located nearby shore
–> transportation distance of ships to transport extracted oil is reduced
–> saves time and money for oil producing companies
What process is used to produce ammonia
The Haber Process
Why is it important to operate and maintain operations at optimal reaction conditions.
To ensure that the most cost-effective chemicals can be produced.
List the results from optimal reaction conditions
- reduced production costs
- lower price for consumers
- greater net profit margin to remain competitive
Write a chemical formula for the Haber Process
3H2(g) + N2(g) <-> 2NH3(g) ; Forward reaction is exothermic.
What happens in the haber process is temperature is increased
LCP predicts that since the forward reaction is exothermic, if temp is increased the system will shift equilibrium to the left to counteract the added heat. This reduces the yield of ammonia since more reactants are formed.
What happens in the haber process is temperature is decreased
–> decrease temp
–> equilibrium shifts right
–> driving the reaction forward
–> produces more yield of ammonia
What state are the species in in Haber process?
gaseous state
If the reaction occurs in a gaseous state what can be concluded about volume, pressure and concentration
increase pressure –> equilibrium shifts right –> overcomes the increase in gas conc. –> increase yield of ammonia
decrease pressure –> equilibrium shifts left —> in favour of reverse reaction –> overcome the decrease in concentration –> decreases yield of ammonia
Is the optimal reaction condition to produce ammonia:
- lowest temp
- highest pressure
no
Why is operating at lowest temp not optimal for haber process
collision theory
low temp –> low kinetic energy –> collision energy of reactants will be lower than activation energy required to break polar covalent bonds –> frequency of collision decrease–> rate of reaction will be 0
What is the optimal temperature to be operating at to produce ammonia
approximately 400 degrees celsius
Why can’t the haber process use extremely high pressures to drive the produce of ammonia?
high pressure on reaction vessel walls –> risk of explosion
What is the optimal pressure to be operating at to produce ammonia
200atm
What catalyst is used and why in the haber process
- iron oxide catalyst
- provides an alternate reaction pathway with lower activation energy to overcome
what is theoretical yield
the moles of product expected to form using mole ratio
–> dependent on the assumption that all moles of reactants will convert into product
what is actual yield
the actual moles of product formed for the reactants that is supplied as raw material
how to calculate percentage yield
actual yield/ theoretical yield x 100
what causes the difference between actual yield and theoretical yield?
purity
how can purity cause a difference between actual yield and theoretical yield?
if the reactant is not pure, the actual moles of the reactant that could produce the product is reduced.
List two places you see the measurement of purity in industry
- The purity of a drug is particularly important in the pharmaceutical industry
- Sydney Water monitors and test the purity of water to ensure that it meets the regulatory requirements
why is it important to plan and design reaction pathways?
To identify whether waste or by-product formed can be recycled as a reactant or drive for other reactions
–> improve cost efficiency and lower cost of production
give an example of how planning and designing reaction pathway can be beneficial
coke ovens –> heat coal –> coal used for steel production –> by product is ammonia gas –> gas is collected and reacted with sulfuric acid to form ammonium sulfate
Whats an environmental concern of chemical synthesis
waste is toxic and harmful to environment
Whats an example of waste produced from a chemical synthesis
the release of sulfur dioxide from steel manufacturing plants involved in smelting iron ore.
SO3(g) + H2O(l) ->H2SO4(g) (sulfuric acid)
How can sulfuric acid be dangerous
- sulfuric acid can dissolve in waterways
- lowers pH of water
- threaten aquatic biodiversity
- economic implication (decline export –> price of fish increase –> reduce affordability of seafood)
describe a social issue related to chemical synthesis and design
fertiliser and pesticides used in agriculture can be toxic to farmers and the exposure can lead to a range of health issues such as respitory problems and cancer
economic issues in regards to chemical synthesis and design is dependent on what?
- profit margins
- government limitations
To remain competitive what much businesses do
focus on production and cost efficiency during manufacturing process
how can economy play a role in the sale price of products
government regulations may impose greater cost on cost of production by disallowing the use of a certain chemical in the manufacturing process
