Question

1. Explain how a concentration dependant monomer-dimer equilibrium agrees with Le Châtelier’s principle. Hint, in order for a dimer to form two monomers must collide and dimers, once formed, do dissociate after a period of time.

Answer 1

Le-chateliar's principle guides perfectly in understanding the study of equilibrium with respect to achievement and direction of it in a reversible reaction. It is purely theoretical.

It can be assessed , concentration or pressure or temperature or catalyst , how they influence the direction of the equilibrium by Lechaltier principle.

in the given question it is to be understood how concentration influences equilibriumof a monomer -dimer process.

Monomer dimer

The rate of formation of dimer is directly propertional to the concentration of the monomer.

dimer is formed by collision of monomers. Higher the concentration of monomers higher the collsions probabilty between monmer molecules and higher will be formation of dimer.[temperature is another parameter to explain about collision among molecules , but here only concentration is dealt as asked in question]

so rate of formation of dimer is directly proportional to the concentration of the monomer which we may undrrstand as RATE OF COLLISSIONS AMONG MONOMER MOLECULES.

After reaching the certain concetration of the dimer , it will start dissocitaion since it is a reversible reaction. Equilibrium is studied in reversible reactions with the help of Lechaltier principle.

so rate of dissociation is again the formation of monomer back.

The equilibriu condition between a monomer and dimer equlilibrium process is that when the rate of collissions of molecules of monomer equals the rate of dissociation of dimer into two monomer molecules again.

This is how the scope of understanding of monomer -dimer equilibrium on a purely theoretical grounds.