Topic 6: Equilibria

Question 1

Dynamic equilibrium requirements

Answer 1

-Rate of forward and backward reactions are equal
-Concentrations of reactants and products are not changing
-Closed system

Question 2

Le Chatelier’s principle

Answer 2

When a factor is changed in an equilibrium, the equilibrium will shift to oppose that change.

Question 3

Temp decrease on equilibrium

Answer 3

Forwards reaction is exo/endo. Shifts equilibrium to oppose decrease in temp (left/right). Equilibrium shifts towards exothermic reaction.

Question 4

Pressure increase on equilibrium

Answer 4

More molecules (moles) on (left/right). Equilibrium shifts to oppose increase in pressure. Equilibrium shifts to side of less moles (right/left).

Question 5

Catalysts effect on equilibrium

Answer 5

Wont shift reaction. Catalyst speeds both reactions equilibrium. Equilibrium will be reached faster.

Question 6

Haber process equation and equilibrium conditions with actual and why used.

Answer 6

N2 + 3H2 <===> 2NH3
High pressure (costly - expensive equipment)
Low temp (however slow rate)
Increased yield of ammonia.
450*C 200atm, iron catalyst

Question 7

Equilibrium Constant Kc
A+2B <===> C+3D

Answer 7

Kc= [C][D]^3/ [A][B]^2
products/reactants

Question 8

[] Meaning

Answer 8

conc. (moldm^-3)

Question 9

Kc changing

Answer 9

Only changes with temp., doesn’t change with concentration

Question 10

Kc units

Answer 10

Cancel out all units of top and bottom, eg mol^-1dm^3