Does Le Chatelier's principle apply to electrochemical cells?

Le Chatelier's Principle is very important when applied to electrochemical cells.

Consider the Daniel Cell:

The 2 half cells are:

#Zn^(2+)+2erightleftharpoonsZn# #E^(o)=-0.76"V"#

#Cu^(2+)+2erightleftharpoonsCu# #E^(0)=+0.34"V"#

To find #E_(cell)^(0)# you subtract the least positive value from the most positive value:

#E_(cell)^(0)=+0.34-(-0.76)=+1.1"V"#

And the cell reaction is therefore:

#Zn+Cu^(2+)rarrZn^(2+)+Cu#

These refer to standard conditions i.e unit concentrations, 298K and pH zero.

What would happen if we were to reduce the concentration of #Cu_((aq))^(2+)# from #1"mol/l"# to #0.1"mol/l"# ?

Looking at the Cu2+/Cu half - cell Le Chatelier's Principle would predict that would cause the position of equilibrium to shift to the left to produce more Cu2+.

This would cause the #E^(0)# value to become less positive. This would therefore reduce the potential difference between the 2 half - cells and therefore the value of #E_(cell)#.

We can calculate the new value using the Nernst Equation which in this case is:

#E_(cell)=E_(cell)^(0)-(0.0591)/(2)log([[Zn^(2+)]]/([Cu^(2+)]))#

#E_(cell)=1.1-(0.0591)/(2)xx1#

#E_(cell)=+1.07"V"#

So as predicted by Le Chatelier,. the value of #E_(cell)# has been reduced.