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.
no net reaction occurring because the rate of forward and reverse reactions have both ceased and are essentially zero.
Define Le Chateliers principle.
When an equilibrium is disrupted (due to temp, concentration, volume, pressure), the system will shift to minimse the disruption .
Mostly affects gases. Some affect to liquid. Solids remain prettu constant
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 AKA all the H+’s leave the building.
When the H+ ions fully disassocate = greater concentration
What is Ksp?
used to predict solubility.
Ksp=[C]^c[D]^d
Ksp represents the maximum amount of solute that can dissolve in water at equilibrium.
the higher the Ksp the more soluble the compound is
E.G. BaSO4 ksp = 1.1x10^-10 at 25degrees C.
The product of concentrations of Ba2+ and SO4, 2- cannot exceed this value OR a precipitate forms
ION product (Q) compared with Ksp
Q< Ksp = no precipitate
Q = ksp = solution at equilibrium, satured
Q> Ksp = Precipate forms BaSO4
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
What does higher concentrations do to the amount of particles present in a solution?
A higher concentration means that more particles are present in the same volume, hence, there will be a greater frequency of collisions which will increase the rate of reaction.
What is the common ion effect. And explain its impact
The common ion effect is observed whenever a given ion is added to a solution that already contains some of that ion.
The addition of a common ion to a system disturbs the equilibrium of a saturated solution, shifting the reaction to the left. This results in a decrease in the solubility of a compound.
What does high KSP mean
High Ksp: A large Ksp value indicates that the compound is highly soluble, with a relatively large concentration of ions in the saturated solution
high ksp e.g. 10*-4 * vs 10 -9
What does low ksp mean?
Low Ksp: A small Ksp value means the compound is poorly soluble, with only a small amount of ions dissolved at equilibrium
IQ1
What is your example of reversible chemical reactions
Iron (III) Nitrate and potassium Thiocynate
Forms bloodred Iron(III) thiocynate complex)
Fe³⁺(aq) + SCN⁻(aq) ⇌ FeSCN²⁺(aq)
Potassium and Nitrate are spectator ions.
Disturbances and affects:
↑ [Fe³⁺] or [SCN⁻]: Shifts → right, more collisions, ↑ FeSCN²⁺ (deeper red).
↓ [Fe³⁺] or [SCN⁻]: Shifts → left, fewer collisions, ↓ FeSCN²⁺ (paler).
↑ Temperature (endothermic reverse favoured): Shifts → left, FeSCN²⁺ breaks down (paler).
↓ Temperature: Shifts → right, more FeSCN²⁺ (deeper red).
↑ Pressure / ↓ Volume: Negligible effect (same number of aqueous particles both sides).
