equilibria

Question 1

What is dynamic equilibrium ?

Answer 1

• when the forward and backwards reactions are happening at the same rate
• and the rate remains constant
• and the concentrations of reactants and products remains constant
• it can only occur in closes systems , wen no substances can get in or out to influence the reaction

Question 2

What is Le Chatelier’s principle ?

Answer 2

• if an external condition is changed the equilibrium will shift to oppose the change ( and try and reverse it )

Question 3

What is the effect of temperature on the equilibrium ?

Answer 3

• increasing temperature: equilibrium will shift to oppose and move in the endothermic direction to reduce the temperature to absorb heat
• decreasing temperature: equilibrium will shift to oppose this and move in the exothermic direction to try and increase the temperature by releasing heat
• remember to think of it as the heat of the surroundings is increasing, and in a reaction hat is either taken in or released to surroundings

Question 4

What compromises commonly have to be made with temperature ?

Answer 4

• yield compromises
• a low yield ( in an exothermic reaction ) will give a higher yield
• but will have a low rate of reaction
• so a compromise has to be found

Question 5

What is the effect of pressure on equilibrium ?

Answer 5

• increasing pressure: will cause equilibrium to shift to the side with fewer moles of gas to reduce the pressure
• decreasing pressure: will cause equilibrium to shift to the side with more moles of gas to oppose the change and increases the pressure
• if the number of moles is the same on both sides then chaining the pressure will have no effect on the position of equilibrium

Question 6

What compromises do we have to make with pressure in reactions ?

Answer 6

• increasing the pressure will usually give a higher yield of product and gives a faster rate
• however industrially high pressure are expensive to produce ( there are high electrical costs for pumping the gases to make the high pressure )
• and the equipment to contain the high pressure is expensive

Question 7

What is the effect of concentration on the position of equilibrium ?