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Flashcards in Dynamic Equilibrium Deck (11)
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Reversible reactions

Both forward and backward reactions occur at the same time


Dynamic equilibrium

Rate of forward is equal to the rate of the reverse reaction
Conc of reactants and products do not change
To be in equilibrium, must be in a closed system


Le Chatelier’s principle

When a system in equilibrium is subjected to external change, system readjusts to minimise effect of change


Effect of concentration changes

More products formed, p of e => if there is an increase in reactant
More reactant formed, p of e <= if there is an increase in product


Investigating concentration changes

2CrO4 2- + 2H+ <=> Cr2 O7 2- + H2O
Yellow. Orange
Add sulphuric acid, orange, increase in H+, more product formed
Add sodium hydroxide, yellow, increase in water, more reactant formed


Effect of temperature changes

Increase temp, p of e => endo
Decrease temp, p of e => exo
Forward and reverse directions have opposite enthalpies


Investigating temperature changes

-∆H Co(H2O)6 2+ +4Cl- <=> CoCl4 2- +6H2O +∆H
Pink. Blue
Hot water bath, blue, move to right, cool down
Ice water, pink, move to left, heat up


Effect pressure changes

Increase pressure, p of e moves to side with fewer moles
Decrease pressure, p of e moves to side with more moles


Investigating pressure changes

2NO2 <=> N2O4
Brown. Colourless


Catalysts and equilibrium

No effect on p of e
Increase rate of forward and backward
Increase rate at which equilibrium is established


Haber process

N2 + 3H2 <=> 2NH3 ∆H=-92kj mol-1
Ideal conditons, low temp, rate too slow
High pressure, safety and failure in steelworks is fatal
Compromise made 350-500C, 100-200atm, iron catalyst
Good yield achieved quickly