Optimising Production Flashcards
(17 cards)
Yield
Quantity of the product that was obtained in a chemical process.
Higher yield = More efficient process
% Yield
Actual yield divided by theoretical yield x 100
Actual Yield
the quantity of product recovered.
Theoretical Yield
the quantity of product predicted by the stoichiometric ratio.
Maximising Yield
Conditions that give the highest yield may not give the fastest rate of reaction (yield vs rate) Must be balance.
Some yield may be sacrificed to permit an economic rate of formation of a product.
High Pressure: Viability
- Maintaining high pressure - expensive & dangerous
- high-pressure equipment needs constant maintenance and repair.
- only cost-effective if profit generated from higher yield exceeds the money required for maintenance.
Temperature
If the reaction is exothermic higher temps cause the equilibrium to shift towards the formation of reactants, reducing yield.
Low temps - not favourable as rxr decreases = increase in costs for power generation and staff wages.
Compromise is made between yield and rxr of product.
Catalysts
increase rate of formation of products.
- minimises the reaction time = reduces operating costs.
- not used up in reaction - can be resued through the process.
- Less energy required for heating = benefits environment by reducing fossil fuels emissions. (less energy demand).
Catalysts DIsadvantages
High purity metals - expensive
Need replacement overtime.
Haber Process
An industrial process used to produce ammonia.
Increase temp - rate of formation of product increases; economic rate of formation ^.
Ammonia produced is lower under certain conditions
these provide an economical yield of ammonia (in terms of cost and time).
The Contact Process
Most sulfuric acid is produced through this process.
First step - burning elemental sulfur or metallic oxides (zinc) in air at high temps to produce sulfur dioxide.
Mixture of S02 and air is passed through beds containing vanadium pentoxide catalyst. Forming S03.
Contact Process Conditions
- Atmospheric Pressure used
- Modertaly high temp - to increase rxr
- conditions used to provide most economical yield of S03.
Industrial chemical process
consists of an intergrated series of chemical reactions and associated steps
Raw materials converted to desired products.
Raw Materials
Unprocessed material - reactants
E.g. coal for electricity, crude oil for fuel production
Waste Products
unusable product; unwanted undesirable - difficult to dispose of.
By-products
Have secondary use on-site or can be sold to generate profit.
