Unit 2) 1) Equilibria , Factors Affecting Equilibrium And The Equilibrium Constant Flashcards
What does it mean by “ a reaction is in equilibrium”
Some reactions never go to completion but are in a state of dynamic equilibrium
A chemical reaction is said to be in equilibrium when the rate of the forward reaction is equal to the rate of the reverse reaction : so the forward reaction and E verse reaction do not stop
At equilibrium the concentration of reactants and products will be ________ but not ________
At equilibrium the concentration of reactants and products will be constant but not equal
What is a closed system
In a closed system heat is able to be ________ to or from surroundings
For an equilibrium to establish the reaction must take place in a closed system : this is where the chemicals are trapped and nothing is added or removed , but heat is allowed to be transferred to or from the surroundings
What did Henri le chatelier say about equilibrium
“If a system is at equilibrium and a change is made in any of the conditions ,then the system responds to counteract the change as much as possible”
- in other words if you make a change to a reaction at equilibrium , the system will alter the concentrations to minimise the effect until equilibrium is re established.
How can the position of equilibrium be altered
- altering concentration of reactant or product
- altering pressure (increasing or decreasing )
- altering temperature (increasing or decreasing )
Effect of concentration on equilibrium position
Increasing concentration of reactant - equilibrium shifts right
Increasing equilibrium of product - equilibrium shifts left
Effect of temperature on equilibrium position
Increasing temperature - equilibrium shifts in direction of the endothermic reaction
Decreasing temperature- equilibrium shifts in direction of the exothermic reaction
Effect of pressure on equilibrium position
Increase in pressure - equilibrium shifts to side with least moles of gas
Decrease in pressure - equilibrium shifts to side with most moles of gas
Composition of equilibrium mixtures
Look at notes for examples and explanation
What is equilibrium constant
The equilibrium constant is a mathematical relationship that shows how the concentration of the products vary with the concentration of the reactants
What symbol does the equilibrium constant have , what symbol does it have when in terms of concentration
Equilibrium constant is - K
In terms of constant Kc
Equilibrium constant of general equation aA + bB —— > < cC + dD
Kc = [C]^c x [D]^d / [A]^a x [B]^b
- where the brackets indicate the concentration of species present at equilibrium , this is then raised to the power of the number of moles of that species from the balanced equation
(Look in notes it makes more sense)
What is a homogenous equilibrium
In a homogenous equilibrium , all the species present at equilibrium are all in the same state
Worked out examples of equilibrium constant expressions
Look in notes ! Important
Does K have units
No , K does not have units