1.6- Equilibria Flashcards
What is the meaning of dynamic equilibrium
Dynamic means both forward and backward reactions are occuring simultaneously , the concentrations of the reactants and products stay constant
What is le chateliers principle
If an external condition is changed then equilibrium will shift to oppose that change
What is the effect of temperature on equilibrium
If temperature is increased the equilibrium will shift to oppose this and move in the endothermic direction to try reduce the temperature
What is the effect of pressure on equilibrium
Increasing pressure will cause the equilibrium to shift towards the side with the fewer moles of gas to oppose the change and therby reduce the pressure
What is the effect of concentration of equilibrium
Increasing the concentration causes the equilbrium to shift to oppose this and move in the direction to remove and decrease the concentreation
What is the effect of catalysts on equilibrium
A catalyst has no effect on the position of equilibrium, but it speeds up the forwards and backwards reactions by the same amount
Outline the production of methanol from CO
.CO + 2H2 > CH3OH
. Exothermic reaction
. 400 deg, 50 atm, with a chromium and zinc oxide catalyst
Outline the hydration of ethene to produce ethanol
.CH2=CH2 + H20 > CH3CH2OH
. 300 deg , 70 atm, concentrated phosphoric acid catalyst
What sort of compromises have to be met with industrial equilibrium reactions
Lower temp can be used which leads to lower energy costs, however this may decrease the yield if it is an endothermic reaction also may slow down the rate of reaction
High pressure leads to too high energy costs for pumps to produce the pressure and too hgih equipment costs to have equipment that can withstand the high pressures
Why is the production of methanol using CO not carbon neutral
The carbon monoxide used to make the methanol is not extracted from the atomosphere , the energ required to carry out the reaction is also made by the combustion of fossil fuels
What does carbon neutral mean
The term carbon neutral refers to an activity that has no net annual carbon emissions to the atmosphere
What is the equilibrium equation for eA + fB > gC + hD
[C]^ x g[D]^h / [A]^e x [B]^f
Give the steps for calculating the equilbirum constant for the equation
. First you have to find out all of initial moles of the products and reactants
. You then work out the change in the moles for one of the molecules, and then use this ratio to work out the change in moles for all the other molecules
. After you have done this you have to find the concentration by dividing the moles by the volume
. After you have found all of the concentrations you can then use these to work out the equilibrium constant for the equation
What is the effect on changing the temperature for Kc
Both the position of equilibrium and the value of Kc will change if the temperature is altered, if temp is increased in an endothermic reaction the value of Kc will become larger as there are more reactants
What is the effect on changing the pressure on equilbirium and Kc
The position of equilbrium will change if the pressure is altered, but the value of Kc stays constant as Kc only varies with temperature
