kinetics and equilibrium

Collision theory

If two molecules collide they may react if at activation energy and at right orientation

Steric hindrance

-when the shape of the molecules influence reactions

-large molecules can prevent reactions

Effect of concentration / pressure on rate

-if conc increases, there are more frequent collisions so more successful collisions

-on a graph, a higher conc has a higher tangent levels off first

The effect of surface area

For heterogeneous reactions involving a solid, a larger surface area leads to a faster reaction

Exposes more reactant particles

Applies to catalyst too

Homogeneous Catalyst

The catalyst is in the same phase as the reactants

Heterogeneous catalyst

The catalyst is in a different phase to the reactants

Example of catalyst in industry

Hager process- heterogeneous catalyst

Benefits of catalysts

-save energy costs and fewer co2 emissions

-more desired product quicker

How does catalyst work in terms of surface

Solid catalyst provides surface where gas molecules can absorb and then react. The product molecules then desorb from the surface and more reactant molecules take their place

Conditions for dynamic equilibrium

-reversible reaction

-closed container

Features of dynamic equilibrium

-the rate of the forwards reaction is equal to the rate of the backwards reaction

-both forwards and backwards reactions are continuously happening

-the concentration of reactants and products remain constant

Effect of temperature change on equilibrium

Increase temperature, the endothermic reaction is favoured

Increase pressure

Favours reaction with less moles

Why do we need to compromise conditions

Rate of reaction and yield