Pt(s) | H2(g, 2.0 bar) | H+ (pH = 3.0) || Cl -(aq, 0.85 mol·L-1)) | Hg2Cl2(s) | Hg(l)
I need to calculate the voltage of the cell. I have a pretty good idea of how to use the Nernst equation for this, but am unsure if I am calculating the concentration of H+ correctly. I calculated the concentration to be 10^-3 given that pH=[H3O+]
If it says pH = 3, then (H3O+) = 1 x 10^-3 M.
Yes that's what I used to to try to find the voltage. But my answer is still coming out to be -.1833 which is incorrect
Are you squaring it?
H2 ==> 2H^+ + 2e
E = Eo-(0.0592/2)log(1/(H^+)^2
As I wrote this I remember I may have contradicted myself about how the Q is written. When working with this equation, it is log (red/ox). If working with the full equation, it is K.
where does the .0592/2 come from? I've been calculating my RT/nF to be .025693/2 ....this is all so confusing...
ln RT/F = 2.303*log(RT/F)is 0.0592 at 25 degrees C(298.15 K) So RT/nF becomes 0.0592/n at 25 C. To get 0.02569... you aren't converting ln to log. Take your number and multiply by 2.303. I THINK that gives 0.05916 and most texts round to 0.0592/n
[2.303*8.314*298.15/96,485]=0.0591669.
Pt(s) | H2(g, 1.0 bar) | H+ (pH =?) || Cl -(aq, 1,0mol·L-1)) | AgCl(s) | Ag(s).
Como calcular o Ph?
To calculate the voltage of the cell using the Nernst equation, you need accurate concentrations of the species involved. In this case, you are trying to calculate the concentration of H+.
The pH of a solution is defined as the negative logarithm (base 10) of the hydrogen ion concentration ([H+]). So, if you know the pH, you can use the formula:
[H+] = 10^(-pH)
In your case, the given pH is 3.0. Plugging this into the formula, you get:
[H+] = 10^(-3.0)
Calculating this expression gives you:
[H+] = 0.001 M
Therefore, the concentration of H+ is 0.001 M.
Now that you have the concentration of H+, you can use it in the Nernst equation to calculate the voltage of the cell. But before that, make sure to double-check the oxidation states and balance the redox reaction and identify which species act as the anode and cathode.
Once you have those details, you can use the Nernst equation:
E(cell) = E°(cell) - (RT/nF) * ln(Q)
Where:
E(cell) = Cell potential
E°(cell) = Standard cell potential (based on standard electrode potentials)
R = Gas constant (8.314 J/(mol·K))
T = Temperature in Kelvin
n = Number of electrons transferred in the balanced half-reaction
F = Faraday constant (96,485 C/mol)
Q = Reaction quotient (ratio of product concentrations to reactant concentrations)
By substituting the values and calculating the Nernst equation, you can determine the cell voltage.