Are All Chemical Reactions Reversible?

[tonyjk]

Hello,
"Reversible processes are at equilibrium : Driving force is only infinitesimally greater than the opposing force Process occurs in a series of infinitesimal steps, and at each step the system in at equilibrium with the surroundings It would take an infinite amount of time to carry out. However Irreversible Process are not at equilibrium; thus a spontaneous process"

http://www.columbia.edu/itc/chemistry/environmental/lectures/Ch_13.pdf page 4.

During irreversible chemical reaction, the reaction is happening in one direction. My question is does the reaction is also happening in the second direction but at lower rate? Or it depends (Some of chemical reaction can occur in both directions but at different rate however others can only occur in one direction like combustion)?

Thanks.

 

[Chestermiller]

You are aware that the terms reversible and irreversible in the context of the thermo-mechanical part of thermo are different from the terms reversible and irreversible in the context of chemical reactions in thermo, right? (An unfortunate circumstance)

Chet

 

[tonyjk]

You are aware that the terms reversible and irreversible in the context of the thermo-mechanical part of thermo are different from the terms reversible and irreversible in the context of chemical reactions in thermo, right? (An unfortunate circumstance)

Chet

Yes

 

[Chestermiller]

Yes

All reactions are reversible to some extent. It's just that for reactions that we call irreversible, the thermodynamics strongly favors the products over the reactants. In terms of kinetics, this means that the reverse reaction rate is much slower than the forward reaction rate. Equivalently, in terms of thermo, the equilibrium constant is very large.

Chet