Equilibrium

what is the definition of equilibrium ?

Is the state achieved when forward and backward recations are occuring at equal rates.

Chemical equilibrium is .. ?

A dynamic , not a static state

At all equilibrium the recatants and products co - exist with ?

Constant concentraton

Pic !!!

Position equilibrium

This varies from reaction to reaction and with changes in experimental conditions

Eg : Temperature and Pressure

General description of equilibrium position include

Left : Reactants outweigh products

Right : Products outweigh reactants

Middle : Products and reactants concns similar

The equilibrium state is only achievable when the recation system is ?

Close system : material added nor removed

At constant temperature and pressure

What does the Le Chateiler’s princple do ?

If a recation is already at eqm and reaction conditions are then changed the eqm position will shift in the direction which opposes the applied change

Eg : pressure , temperature , con.c

Le Chatelier’s princple

if the condition of a system at eqm are changed , the position of the eqm moves to oppose that change

Change : Make it hotter

action by eqm : cools it back down

Change : increase in pressure

Action by eqm : decreases the pressure

Change : Add more of a chemical

Action by eqm : use it up , get rid of it

what are the 3 conditions that changes the eqm ?

Temp , Pressure , Con,c

Temperature

Exothermic reaction

Chem energy → heat energy

make the system hotter

Endothermic reaction

Heat energy → chem energy

Make the system colder

example 1) if temperature increases , would it shift left or right ? → exo

N2 ( g ) + 3 H2 ( g ) ←→ 2 NH3 ( g ) =) 76 KJ/mol

Move left, decrease in eqm yield of NH3

Example 2 ) ) if temperature increases , would it shift left or right ? → endo

N2O4 ( g ) ← → 2 No2 ( g ) =) 55 KJ / mol

Eqm move to oppose increases in temp

Moving right of in ends , increase eqm yield of NO2

Pressure

Example 1 ) if pressure increases , would it shift left or right ?

N2 ( g ) + 3 H2 ( g ) ← → 2 NH3 ( g )

4 moles on left and 2 moles on right

Moving right to side with fewer gas molecules, increased eqm yield of NH3

Example 2 ) if pressure increases , would it shift left or right ?

N2O4 ( g ) ← → 2 NO2 ( g )

1 mole on left and 2 moles on right

Moving left to side with fewer gas molecules, decreased eqm yield of NO2

Concentration

Example 1 ). Add more N2 , would it shift left to right ?

N2 ( g ) + 3 H2 ( g ) ← → 2 NH3 ( g )

Moving right to use it up , increase in eqm yield of NH3

Example 2 ) Add some H2 , would it shift left to right ?

N2 ( g ) + 3 H2 ( g ) ← → 2 NH3 ( g )

Moving left to make it up more, decreases in eqm yield of NH3

Changes in conditions : addition of reagent

Moving left

Changes in conditions : removal of reagent

Moving right

Changes In conditions : addition of products

Moving right

Changes In conditions : removal of products

Moving left

Changes In conditions : increase in temperature

Changes In conditions : decrease in temperature

Changes in conditions : Increases in pressure

Changes in conditions : decreases in pressure

Does the addition of catalyst disturb the eqm position ?

NO , it doesn’t disrupt the eqm position, same eqm positions but sooner

Faster reaction as catalyst cause forward and backward reactions to be speeded up equally

CH,(g) + H20(g) = CO(g) + 3H2(g)

L → R favoured by P / T

Low pressure 2 - 4 moles

High temperature (endo)

H2(g) + CO2(g) = CO(g) + H20(g)

L → R favoured by ?

Any pressure 2 - 2 moles

Increase / high temperature ( endo )

H2(g) + C|2(g) = 2HC

L → R favoured by ?

Any pressure 2 - 2 moles Increase

Low temperature ( exo )

2X(g) + 3Y(g) = 2Z(g)

L → R favoured by ?

High pressure 5 -2 moles

Low temperature ( exo )