Topic 10 Equilibrium Flashcards
What is the definition of dynamic equilibrium? Why?
The conc of reactants and products reach a point where they stay constant
Because rate of forward reaction is EQUAL to backward reaction
What is Le Chatelier’s principle?
“A system in dynamic equilibrium will react to oppose any changes made to it”
If more ammonia is added to the Haber process, equilibrium will shift….
To the left hand side,
Ammonia concentration is reduced
If my hydrogen is added to the haber process, equilibrium will shift to….
The right hand side, removing the extra hydrogen
What is the Effect of pressure in equilibrium system? If pressure is increased, equilibrium shifts…
To the side with less number of molecules
If temperature is increased, the equilibrium will shift…
To the endothermic direction
If the temperature is decreased in an equilibrium system, the equilibrium will shift….
To the exothermic direction
In what conditions do change of pressure affect equilibrium?
When reactants and products are gaseous
What are 4 features of a system in dynamic equilibrium? (2 marks)
- forward rate of reaction is equal to backward reaction
- conc of both are constant
(- all reactants and products are present)
(- both reactions occurring simultaneously ))
What are industrial conditions for Haber-Bosch process?
400-450 C
200 atm
Powdered iron catalyst
How to achieve a better yield in Haber process?
- lower temp (but slows RoR)
- higher pressure (but very expensive)
What is the contact process?
Making sulphuric acid (H2SO4)
From S and O2 making SO2, then 2SO2(g)+O2(g)⇌2SO3(g)
Then SO3(g) + H2O(l) ⇌ H2SO4(aq) [sulphur trioxide + water -> sulphuric acid]
What are conditions needed for contact process?
450 C
2 atm
Catalyst V2O5 (Vandium (V) oxide)
What is the Haber process?
Processing making ammonia NH3
What is a homogeneous system?
All reactants and products are the in the same state
What are heterogeneous systems?
System with components that has at least two different phases are present.
What state do we leave out when calculating Kc?
Solids!
How to calculate Kc?
[PRODUCTS]/[REACTANTS]
If the equation was: A+ B –> C + 2D, the Kc equation would become: [C] [D]2 / [A] [B]
[X]^n n=moles
What does [A] mean in Kc equation?
Concentration of A (moldm-3)
What happens when you compress a gas with colour in equilibrium immediately ?
Mixture always goes darker IMMEDIATELY first and then shift to the correct side
Even though equilibrium doesn’t favour that reaction!
Why does nano particles increase rate of reaction over powder? 2 marks
- higher surface area of contact
- more frequent collisions
Why does change of pressure change rate of reaction? 3 marks
- increase pressure increases RoR
- as particles are closer together
- more frequent collisions
Why does student choose polystyrene cup instead of glass beaker?
More insulating to reduce heat loss
What the unit for Kc? (Equilibrium constants)
mol dm -3 each
Cancel out when
[products]^a / [reactants]^b
Why do test tubes need to be put in water bath before equilibrium reaction?
Allow solutions to reach same temp and equilibriate
What state is is left out when calculating equilibrium constants (Kc)? Why?
Solids only, as the conc stays constant
Gases do seperately
