1.6 Equilibrium Flashcards
What are the two features of a dynamic equilibrium?
1) forward and backward reactions are occurring at equal rates
2) concentrations of reactants and products stays constant
What is Le Chateliers principle?
If you change the conditions of a reversible reaction at equilibrium the system will try to counteract that change
What is the effect of temperature on equilibrium?
Equilibrium will shift to oppose the increase in temperature by moving in the endothermic direction. This is to reduce the temperature by absorbing the heat.
Equilibrium will shift to oppose the decrease in temperature by moving in the exothermic direction to try to increase the temperature by giving out heat
What effect would increasing the temperature have on the yield of ammonia?
N2n+ 3H2 —> 2NH3
Equilibrium will shift to oppose the increase in temperature by shifting in the endothermic, backwards direction. The position of equilibrium will shift left, giving a low owed yield of ammonia.
(Lower temperatures may give a higher yield of product but will also result in slow rates of reaction. Often a compromise of the temperature is used that gives us a reasonable yield and rate)
What is the effect of pressure on equilibrium?
Equilibrium will shift to oppose the increase in pressure by favouring the reaction which produces less moles, which reduces the pressure.
Equilibrium will shift to oppose the decrease in pressure by favouring the reaction which produces more moles, whihc inreases the pressure
What effect would increasing the pressure have on the yield of methanol?
CO(g) + 2H2(g) —> CH3OH(g)
Equilibrium will shift to oppose the increase in pressure by favouring the forward reaction as it produces 1 mole versus 4 moles of gas. Therefore the yield of methanol would increase
What happens if the number of moles of gas is the same on both sides of the equation?
The change in pressure will have no effect on the position ofequilibumr
H2 + Cl2 —> 2HCl
What happens when you increase pressure
Increasing pressure may give a higher yield of product and will produce a faster rate of reaction.
Industrially higher pressures are expensive to procure (high electrical energy costs for pumping the gases to make a high pressure)and the equipment is expensive.
What is the effect of concentration on equilibrium
Equilibrium will shift to oppose the increase in concentration by favouring the reaction that uses that substance as a product. This reduces the concentration of the substance and increases the yield of the products of that reaction
What is the effect of catalysts on equilibrium?
A catalyst has no effect on the position of equilibrium, yet it will speed up the rate at which equilibrium is achieve - this is because it speeds up the rates of the forward and backwards reactions and equal rates
What are the conditions of the haber process?
Temp - 450°c
Pressure - 200 atm
Iron catalyst
Why are the specific conditions used for the Haber process
Low temp gives a good yield but a slow rate: comprise temp used
High pressure gives good yield and high rate: too high a pressure would lead to too high energy costs for pumps to produce such a pressure
What is the equation for the Haber process?
N2 + 3H2 <—> 2NH3
What are the conditions for the production of methanol
CO(g) + 2H2 —> CH3OH
temp - 400°c
Pressure - 50 atmospheres
Chromium and zinc oxides as catalysts
Give the equation and conditions for the hydration of ethene to produce ethanol
CH2=CH2(g) + H2O —> CH3CH2OH(l)
Temp - 300°c
Pressure - 70 atm
Concentrated H3PO4 as a catalyst
