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Flashcards in Dynamic Equilibrium Deck (11)
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1

Reversible reactions

Both forward and backward reactions occur at the same time

2

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

3

Le Chatelier’s principle

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

4

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

5

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

6

Effect of temperature changes

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

7

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

8

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

9

Investigating pressure changes

2NO2 <=> N2O4
Brown. Colourless

10

Catalysts and equilibrium

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

11

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