Equilibria Flashcards
What are ignored in the Kc expressions for HETEROGENOUS equilibria?
substances with CONSTANT CONCENTRATION e.g. solids.
define dynamic equilibrium.
The forward and backward reactions (changes) continue at EQUAL RATES so that overall there is not change.
Define partial pressure.
The pressure a gas would exert if it alone filled the container.
what happens when more of a reactant is added to a system at equilibrium?
adding more of a reactant to a system at equilibrium means that the mixture is no longer at equilibrium - some of the added chemical reacts and more products form until the system is again at equilibrium.
What effect does a decrease in pressure have on equilibrium?
Increases VOLUME –> more ways to distribute molecules + higher ENTROPY - favours direction that produces more molecules.
What does a change in pressure do to equilibrium?
changes the Kp ratio - eqm shifts to restore the balance.
Why does increased pressure increase the rate of reaction?
particles are in a smaller volume and collide more frequently ([ ] effectively increases).
On Kp expressions where does the partial pressure appear?
Inside the brackets.
what can’t equilibrium constants tell us about a reaction? What can they tell us about?
The rate.
Position of eqm / how far the reaction has gone.
How can you improve the yield of an ester?n
excess of alcohol - shifts eqm to the right.
recover unreacted alcohol by distillation + reuse it.
what is the total entropy CHANGE for a system at eqm?
zero.
