Chemistry chemical equilibria

What are the conditions for equilibrium

• must be in a closed system

How do u know when equilibrium has been reached

When the properties of the system don’t change over time

Features of dynamic equilibrium

Forward rate= backwards rate

Concentrations remain constant

What is le chateliers principle

Equilibrium will shift to oppose the change

Factors that affect position of equilibrium

Concentration

Pressure

Temperature

How does concentration affect position of equilibrium

Adding a chemical increases con and equilibrium moves to get rid of it

And remove a chemical equilibrium moves to make more of it

How can pressure affect position of equilibrium

Raise pressure equilibrium moves to lower it and vise versa

How does temperature affect position of equilibrium

Make it hotter equilibrium moves to cool it and vise versa

What happens when reactants concentration is decreased

Equilibrium shifts to the left hand side therefore products formed is also decreased

What happens when total pressure is increased

Equilibrium shifts to oppose the increase in pressure and will shift to desire with fewer gaseous moles to reduce pressure

And if total pressure is decreased

Eq shifts to oppose and moves to side with more gaseous moles

For an exothermic reaction what is the change in temperature

It is negative as system gives out heat

For an endothermic reaction what is change in temp

It is positive as it t,es in heat

For an endothermic reaction what happens if there’s an increase in temp

Eq shifts to the right hand side to absorb heat and reduce temp

Decrease in temp in an endothermic reaction

Shifts to left hand side to oppose decrease in temperature

Exothermic reaction with increase in temp

Eq shifts to the left hand side

Decrease in temp in an exothermic - negative

Eq shifts to the right hand side

What does adding a catalyst do to the yield or position of equilibrium

It has no effect

Optimum temperature of an exothermic ammonia production

Low temperature so Eq moves to rhs

Optimum pressure in exothermic ammonia production

High pressure therefore moving to side with less moles although much more expensive

What do compromise conditions give

A balance between yield, rate and cost

what does a catalyst do in an exothermic reaction of ammonia production

Reduces the time taken for reactions to reach Eq

Production of ethanol optimum temperature

Low temp which results in high yield but a slow rate of reaction therefore a compromise between yield and rate

What is a homogeneous equilibrium

aA + bB _- cC + dD

A system in which the reactants and products are in the same phase

What is kc and how to draw it

Products divided by reactants

What is kc affected

Temp

What are the units for kc

Moldm-3

How to calculate moles at equilibrium use textbook