Unit 3 Flashcards
What are industrial processes designed to maximise and minimise
Maximise profits and minimise the impact on the environment
7 factors that influence the design of an industrial process
availability, sustainability, cost of feedstock, opportunities for recycling, energy requirements, marketability of by-products and product yield.
environmental considerations of chemical processes
minimising water, avoiding use or production of toxic substances, designing products which will biodegrade if appropriate.
molar volume is the same for…
ALL gases at the same temperature and pressure
what is the approximate molar gas volume
22.4 litres mol -1
what are the units used for molar volume
litres mol -1 NOT to be confused with moles per litre
what are the units for concentration
mol l-1
Define the term ‘dynamic equilibrium’
Many reactions are reversible. A reversible reaction can meet equilibrium in a closed system.
When does equilibrium occur
When the rate of the forward reaction is equal to the rate of the backward reaction.
What happens to concentrations at equilibrium
They stay constant
State Le Chatelier’s principle
An equilibrium will move to undo any change imposed upon it by temporarily favouring either the forward or backward reaction until a new equilibrium position is reached.
In increase in pressure favours the side with…
Less Gas particles
Addition of a reagent or removal of a product moves the equilibrium to the
right
Addition of a product or removal of a reagant moves the equilibrium to the
left
Increase in temperature favours the
endothermic reaction
Decrease in temperature favours the
exothermic reaction
State the effect a catalyst has on equilibrium
A catalyst has no effect on the equilibrium position but will help to reach equilibrium faster
State the pressure, temperature and other conditions applied to the haber process
High pressure (balanced by cost of equipment), moderately high temperature (lower temperature improves yield but reaction is then too slow). Unreacted products are recycled, an iron catalyst is used to speed up the reaction.
State the definition of percentage yield
The percentage yield is a measure of how much product is obtained compared to the amount expected if there was a complete conversion.
State the definition of atom economy
The atom economy measures the proportion of the total mass of all the starting materials successfully converted into the desired product.
Explain why there can be a high percentage yield but a low atom economy.
Means a lot of waste products are being produced.
What is Enthalpy
Enthalpy (H) is a measure of the energy stored in a chemical.
State the definition of the enthalpy of combustion
The enthalpy of combustion of a substance is the amount of energy given out when one mole of a substance burns in excess oxygen.
State Hess’ law
The overall enthalpy change for a reaction is the same whichever route is taken.
