Le Chatelier's Principle - What is an equilibrium shift?

[jumbogala]

[SOLVED] Le Chatelier's Principle - What is an equilibrium shift?

When my chemistry textbook says, "the equilibrium shifts to the right", what does it mean?

Is it increasing the rate of the forward reaction to accomplish this?

If a shift in equilibrium is not a change in the rate of reaction, then what is it?

 

[MichaelXY]

Equations go back and forth from reactant side to product side. In other words you go from NaCl to Na + Cl back to NaCl. So, to the right would mean more Na + Cl. I think that's right, maybe someone will smack me for error.

 

[Gannon]

Le Chatelier's principle states that if stress is placed on a reaction in equilibrium, the reaction will push itself in either direction to re-establish the equilibrium. Think of the reaction as a see-saw. Using jumbogala's example:

Na+ + Cl- <=> NaCl

In this equilibrium, the amounts of salt (right) and ions (left) are balanced. If you were to add salt to this reaction, it would force the reaction to the left, producing more reactants (The see-saw's right end is pushed downward, so the reaction must push the left side downward to compensate). It works the same way in the opposite direction.

If we were to remove chloride ions (pushing the see-saw upward on the left), the reaction would shift to the left toward reactants (pushes the see-saw upward on the right).

The rate of reaction only designates how quickly the equilibrium is corrected, not how much of what is created.

 

[nidst7]

Just be careful how you word that-the amounts of Na+ and Cl- are not necessarily (in fact, rarely) equal at equilibrium. Also, if the NaCl is a solid, then addition of NaCl will not affect equilibrium, as only concentrations of aqueous or gaseous substances will affect the position of equilibrium.

To go back to the original question, immediately after the disturbance, yes, the forward reaction rate increases. As equilibrium is reestablished, the forward and reverse reaction rates become equal again. So the system was originally at equilibrium, a disturbance occurs, the system adjusts, and a new equilibrium position is established.