6 -Equilibria Flashcards
What is a reversible reaction?
When products are formed they react together to form the reactants, producing a mixture of both.
What is an equilibrium mixture?
A mixture where the proportions of all components remain constant. (in a closed system).
What is dynamic equilibrium?
When the rate of the forward and backward reactions are the same.
The concentration of products and reactants are constant.
What are the 4 conditions for equilibrium?
Closed system
Products and reactants present at the same time.
Equilibrium can be approached from both sides.
Dynamic process - forward and backward reaction at the same rate.
Explain the shape of a rate of reaction graph against time.
At the start of the reaction the forward rate is fast as the reactants are plentiful.
As the concentration of products builds up the reverse rate speeds up and the reactants concentration decreases.
When the rates are the same equilibrium is reached.
What is Le Chatelier’s principle?
If a factor is changed which affects the equilibrium mixture the position of equilibrium will shift as to oppose the change.
(Not say how far it moves).
What effect does increasing concentration have on equilibrium?
The position of equilibrium will shift to reduce the concentration.
What effect does increasing pressure have on equilibrium?
The position of equilibrium shifts to the side with fewer gaseous molecules to decrease the pressure.
Only affects reactions with gases.
What effect does increasing temperature have on equilibrium?
The position of equilibrium will shift in the direction that cools down the system, to the endothermic side.
What effect does decreasing temperature have on equilibrium?
The position of equilibrium will shift in the direction that heats up the system, to the exothermic side.
What effect does a catalyst have on equilibrium?
No effect on the position of equilibrium, as it affects the rate of the forward and backward reaction equally.
What is the Haber process?
When nitrogen and hydrogen are passed over an iron catalyst to produce ammonia.
Why is high temperature used for the Haber process?
It is used, even though low temperature would produce a greater yield of ammonia, to speed up the rate of reaction.
Why is high pressure used for the Haber process?
It produces a greater yield of ammonia as Le Chatelier’s principle tells us that equilibrium will shift right to decrease the pressure.
What is the formula for the equilibrium constant?
[products]^mol (eqm)
Kc = ———————————–
[reactants]^mol (eqm)
