Concentrations in a galvanic cell

[Shaybay92]

Homework Statement

I am doing an investigation on the factors that affect the voltage of a galvanic cell (or daniell cell). I have two beakers with zinc and copper strips and zinc sulphate and copper sulphate. How would there be an electrical current produced (significantly lower however) with a 0M concentration of copper ions and a 1M concentration of Zinc ions?

I thought the copper ions attract the electrons, or is it just the copper atoms and then the copper ions pick them up?

 

[Borek]

Nernst equation.

 

[Shaybay92]

But this equation is used to calculate the voltage in a concentration cell? The daniel cell that I am using is not a concentration cell, but two separate beakers with two different solutions?

 

[Borek]

No, Nernst equation can be used to calculate voltage in any type of electrochemical cell.

 

[DinCahill]

If I am correct in saying the reaction quotient Q in the daniell cell is [Zn2+]/[Cu2+], Q in his case would be 1/0. So Eo - RT/zF lnQ would be Eo - Infinity? Does this mean the voltage is zero or infinitely negative?

 

[Borek]

No, concentration of copper (II) is not zero. It may be very low, but once you put copper in water it immediatley reacts till the concentration is high enough so that oxidating potential of H⁺ from water autodissociation equals potential of Cu/Cu²⁺ system.

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[DinCahill]

Makes sense; thanks.