Getting the most from reactants Flashcards
What does the UK chemical industry make a major contribution to?
the quality of life in the country
Give 4 examples of products which are made on a huge scale on a daily basis?
medicines
plastics
paints
cosmetics
What are industrial processes designed to do?
maximise profit and minimise the impact on the environment
Give 5 examples of factors influencing process design ?
availability, sustainability and cost of feedstock(s) opportunities for recycling energy requirements marketability of by-products product yield
Give 3 examples of environmental considerations?
minimising waste
avoiding the use or production of toxic substances
designing products which will biodegrade if appropriate
What is the research and development stage?
initial stage of planning
What is the laboratory process stage?
Initial trial using small quantities
What is the pilot study stage?
Trial using larger quantities in a bigger reactor to understand engineering aspects of the process.
What is the production stage?
Production is carried out in a factory/plant on a huge scale, producing tonnes of products
What is the process and review stage?
The process is reviewed and optimised to have the best conditions and best yield. A marketing team will sell the product.
What is a feedstock?
a reactant from which other chemicals can be extracted or synthesised.
What are feedstocks derived from?
raw materials
What are raw materials?
substances that can be used directly in their original form without being treated.
What are the 5 main raw materials used in the chemical industry?
fossil fuels metallic ores and minerals air water organic materials such as oil and starch
What would make feedstock profit making?
local feedstock
feedstock that is in abundance
low cost of feedstock
When would feedstock cause a profit loss?
feedstock has to be transported for far away
feedstock may become scarce
feedstock is too expensive.
When would opportunities for recycling cause a profit to be made?
if unreacted materials can be fed back into the process this will improve efficiency and profitability.
When would opportunities for recycling cause a profit to be loss?
if it is difficult to separate materials at the end of the reaction, this makes it inefficient and wasteful.
When would energy requirements cause a profit to be made?
exothermic reactions can be used to sustain the heat in a reaction.
catalysts can lower the energy required for the reaction
When would energy requirement cause a profit to be lost?
reactions which require a lot of heating and cooling require energy.
When would marketability of by-products cause a profit to be made?
some by-product can be sold for use in other areas of the chemical industry.
When would marketability of by-products cause a profit to be loss?
if by-products are toxic or corrosive they will be expensive to deal with and may harm the environment.
When would product yield cause a profit to be made?
high yields are very profitable
When would product yield cause a profit to be loss?
low yields cost time and money
What is also important to consider in an industrial process?
thedesign of the chemical plant to ensure it has good infrastructure,i.e. good transport links (road and sea for export and import of materials) and safety precautions
What can a flow diagram be used for?
by engineers and industrial chemists when designing a process. It allows them to consider important aspects of the whole chemical process.
In most chemical reactions what happens to one reactant ?
Gets used up before the other
What happens to the reaction of one reactant is used up?
It stops
What is the reactant left over said to be?
In excess
What is the reactant not in excess called?
Limiting reactant
What does the limiting reactant determine ?
The quantity of product made
What is the molar volume of a gas?
The volume occupied by 1 mole of a gas at a stated room temperature and pressure
What is the approximate molar volume of gas at room temperature (20•c) and 1 atmospheres pressure?
22.4 litres
What is the same for all gases?
22.4 litres at room temperature and 1 atmospheres pressure
Many reactions do not go to completion. What does this mean?
The quantity of product obtained from the reaction (actual yield) is less than the calculated (theoretical yield)
Why would there be a lower actual yield than theoretical yield?
May be due to products being lost or the reaction being reversible
What is the equation for percentage yield?
Actual yield / theoretical yield x100
What is the equation to find the actual yield?
Theoretical yield x %yield/ 100
What does atom economy measure?
The proportion of the total mass of all starting materials converted into the desired products
If by-products were produced what would the atom economy most likely be and why?
Low as there will not be a high proportion of the desired products
What is the equation for atom economy?
Mass of desired product(s)/ total mass of reactant(s) x100
