Module 5 - Equilibrium Flashcards
(20 cards)
Define Dynamic Equilibrium
A reaction that is continulously at work - it appears to not change as the forwards and backwards reactions are occuring at the same rate.
Occurs within a closed system to ensure only an exchange of energy occurs - not exchange of mass.
Define Static Equilibium
no movement/change.
Products remain products, Reactants remain reactants.
Define Le Chateliers principle.
When an equilibrium is disrupted (due to temp, concentration, volume, pressure), the system will shift to minimse the disruption .
ONLY APPLIES TO GASES!
What does a large ‘K’ value indicate when calculating the equilibrium constant?
When K>10^3, the equilibium lies towards the right/products.
Low values of K - towards reactants.
What is your example of equilibrium?
Iron (iii) Thiocyanate
Fe3+ + SCN- –> [FeSCN]2+
Yellow colourless red
ORR Haber process
Define a strong acid
Fully ionises in water.
When the H+ ions fully disassocate = greater concentration
What is Ksp?
used to predict solubility.
Ksp=[C]^c[D]^d
Ksp represents the maximum extent that a solid that can dissolved in solution.
the higher the Ksp the more soluble the compound is
What is the Common Ion effect?
using stoich to determine the value of an unknown - for Ksp.
Then slapping into RICE table.
What factors impact rate of reaction and therefore collision theory?
Temperature
* Concentration
* Gas Pressure
* Catalyst
What is the effect of increasing the pressure in a reaction? (For gases)
Reaction will shift towards/favours species with less gasous moles
What happens when you change the concentration of products?
Reaction tries to decrease [Product] in order to minimise the change.
REVERSE reaction occurs to greater extent since this will use up some Products
Equilibrium shifts to the LEFT
What happens when you increase volume?
Reaction tries to “fill up” the volume by increasing number of gas molecules in the system in
order to minimise the change.
Favours reaction which produces greatest number of total gas particles
What happens when you change temperature?
Increase Temperature
Reaction tries to absorb the excess heat in order to minimise the change.
Favours the Endothermic reaction since this will absorb/use up some of the heat.
Decrease Temperature
Reaction tries to release ‘replacement’ heat in order to minimise the change.
Favours the Exothermic reaction since this will produce/release extra heat.
If reaction is exothermic and you increase temperature, equilibrium shift to LHS.
Equilibrium expression rules!
If gases are present, no other state included in constant expression.
Aqueous substances are included UNLESS there is a gas present!
Liquids are ONLY included when ONLY LIQUIDS are present.
Solids NEVER included.
Define Quotient
expresses the relative ratio of products to reactants at a given instant in time.
used to determine if a reaction is at equilibrium and, if not, which direction it will shift to reach equilibrium
What does it mean if Q=K
System at equilibrium - no shift
What does it mean if Q>K
Reaction will shift towards the reactants
What does it mean if Q<K
reaction will shift towards products
what is a homogeneous equilibrium reaction
when all the molecules are gases
heterogeneous -different states
