Calculating E(cell) and Ratio of [Ni^2+]/[Zn^2+] in a Zn-Ni Cell

In summary, the problem involves calculating the E(cell) for a cell reaction involving Zn and Ni^2+ ions at certain concentrations. The standard potential is determined by adding the half equations and the nernst equation is used to calculate the E(cell). The ratio of [Ni^2+]/[Zn^2+] is then found when the cell is "flat". The answer may vary depending on the values of standard potentials and rounding errors.
  • #1
requal
8
0

Homework Statement



For a cell in which the reaction Zn(s)+ Ni^2+(aq)->Ni(s)+ Zn^2+(aq) calculate the E(cell) when [Ni^2+]=0.05M, [Zn^2+]=0.85M.

Then, find the ratio of [Ni^2+]/[Zn^2+], when the cell is "flat"


Homework Equations



The simplified nernst equation ; E(cell)=E*(cell)-(0.0592V/n)xlogQ, log=log base 10

The Attempt at a Solution



Well I worked out the standard potential by adding half equations

Ecell=ENi-Ezn=0.51V

than because two electons are transferred, n in the nernst equation is 2.

Ecell= 0.51V-0.0592V/2log[0.85/0.05]

I plug that into my calculator, and I get 0.47V; the answer is 0.49V?
I tried doing the second part, and I got it wrong obviously, because I got the first part wrong
 
Physics news on Phys.org
  • #2
I got 0.48V (0.477), it probably depends on values of standard potentials used and/or rounding errors.

But I don't see how the second part depends on the first, looks to me like these are completely separate problems.
 

1. What is the Nernst equation?

The Nernst equation is an equation that relates the equilibrium potential of an electrochemical cell to the concentration of the chemical species involved in the reaction.

2. How is the Nernst equation derived?

The Nernst equation is derived from the principles of thermodynamics and electrochemistry, specifically the Nernst equation is a special case of the more general equation known as the Goldman-Hodgkin-Katz equation.

3. What is the significance of the Nernst equation?

The Nernst equation is significant because it allows us to calculate the equilibrium potential of an electrochemical cell, which is a key factor in understanding and predicting the behavior of electrochemical reactions.

4. How is the Nernst equation used in chemistry?

The Nernst equation is used in chemistry to calculate the equilibrium potential of an electrochemical cell at a given concentration of chemical species. It is also used to determine the concentration of a species in a solution based on its equilibrium potential.

5. What are the limitations of the Nernst equation?

The Nernst equation assumes ideal conditions, such as a perfectly reversible reaction and no changes in temperature or pressure. In reality, these conditions may not always be met, which can affect the accuracy of the calculated values. Additionally, the Nernst equation only applies to electrochemical reactions involving a single electron transfer.

Similar threads

  • Biology and Chemistry Homework Help
Replies
7
Views
3K
  • Biology and Chemistry Homework Help
Replies
1
Views
5K
  • Biology and Chemistry Homework Help
Replies
1
Views
3K
  • Advanced Physics Homework Help
Replies
1
Views
664
  • Biology and Chemistry Homework Help
Replies
10
Views
3K
  • Biology and Chemistry Homework Help
Replies
6
Views
2K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
10K
Back
Top