All Questions
19
questions
0
votes
1
answer
70
views
Can an electrode run out of the active species?
I have a background in solid state physics but am new to electrochemistry. I have been following the example of a physical chemistry (Mortimer) book that looks an electrochemical cell with a hydrogen ...
- 9
0
votes
1
answer
564
views
Degree of dissociation and conductance
My book says ratio of molar conductance at a given concentration of solute and molar concentration at infinite dilution is equal to degree of dissociation for weak electrolytes.
I understand it ...
- 1
2
votes
1
answer
391
views
Electrode potential for saturated silver carbonate solution
An electrochemical cell is set up to measure the electrode potential $E(\ce{Ag^+}/\ce{Ag})$ using the saturated $\ce{Ag2CO3(aq)}$ solution $(K_\mathrm{sp}(\ce{Ag2CO3(aq)},\pu{25 °C}) = \pu{6.3E-12})$ ...
- 65
0
votes
1
answer
170
views
Calculating Gibbs free energy change when the state of ions is unknown
Problem
Calculate $\Delta G^\circ$ for the following reaction:
$$\ce{Zn(s) + Ag2O(s) + H2O(l) -> Zn^{+2}(aq) + 2Ag(s) + 2OH-(aq)}$$
Given $E^\circ_{\ce{Ag+/Ag}} = \pu{0.80 V}$, $E^\circ_{\ce{Zn^{+...
- 1,817
2
votes
1
answer
318
views
Relation between standard silver-silver chloride electrode potential and solubility product of silver chloride
I learned that $E^\circ_\ce{Cl^-|Ag,AgCl}, E^\circ_\ce{Ag^+|Ag}$ and $K_\mathrm{sp}$ of $\ce{AgCl}$ are related as
$$\boxed{E^\circ_\ce{Cl^-|Ag,AgCl} = E^\circ_\ce{Ag^+|Ag} + \frac{RT}{F}\ln K_\mathrm{...
- 750
2
votes
1
answer
225
views
Intuition for relation between electrode potential and reaction quotient
Consider the following reaction in a galvanic cell: $$\ce{X(s) + Y+(aq) -> Y(s) + X+(aq)}$$
According to the Nernst equation, $$E =E_\circ - \dfrac{RT}{F}\ln\left(\dfrac{\ce{[X+]}} {\ce{[Y+] }} \...
- 750
1
vote
1
answer
221
views
Why is "activity" of gaseous component equal to its partial pressure but that of aqueous component its concentration?
While solving an electrochemistry problem I had to calculate the reaction quotient of this reaction:
$$\ce{2Fe(s) + 4H+(aq) + O2(g) -> 2Fe^{2+} (aq) + 2H2O (l)}$$
It turns out to be: $$\ce{Q=\dfrac{...
- 750
3
votes
0
answers
174
views
Why aren't electrons included in the equilibrium constant expression?
This might be elementary, but why aren't electrons included in the equilibrium constant for a half-reaction?
For example, for
$$\ce{O2 (g) + 4H+ (aq) + 4e- -> 2H2O(l)}$$
we have
$$Q = \frac{(a_\ce{...
- 1,241
2
votes
2
answers
2k
views
Origin of electrode potential and its connection with electric double layer
Recently, I was learning about electrode processes and I came across the topic of "electrode potentials".
I understood that at equilibrium, a potential difference was generated at the ...
- 221
0
votes
2
answers
489
views
How does current start to flow when galvanic cell is first connected?
Using the Daniell Cell as an example, where in the steady state we expect zinc to be oxidised and copper to be reduced spontaneously due to the overall reduction in Gibbs free energy, how does the ...
- 103
4
votes
1
answer
8k
views
How is the formula of mean activity coefficient derived?
The mean activity coefficient is defiend as follows:
$$\gamma_\pm = (\gamma_+\gamma_-)^{1/2}.\tag{1}$$
If Debye-Hückel equation
$$-\log\gamma_i = 0.5z_i^2\mu^{1/2}\tag{2}$$
is used, then the mean ...
- 143
2
votes
0
answers
36
views
Why isn't the chemistry of a zinc-air battery (meaningfully) hindered by an activation energy barrier?
Virtually every source I've read pertaining to zinc-air batteries explain the chemistry of it either using these formulae or a simplified version of them:
$$
\begin{align}
&\text{Anode:} &\...
- 139
2
votes
0
answers
110
views
Calculating Ka using Nernst Equation
I've heard multiple times that the Nernst Equation could be used to calculate K$_a$. How would one calculate the acidity constant, K$_a$, of a specific acid, using the Nernst Equation? The equilibrium ...
2
votes
3
answers
2k
views
Why is the voltage produced by a voltaic cell affected by temperature as described by the Nernst Equation?
I understand why changing the concentrations of the electrolytes in a voltaic cell affects the voltage. Given a zinc-copper cell for example, if I were to increase the concentration of the zinc ...
- 71
2
votes
1
answer
2k
views
Determining the reduction potential of a half cell reaction at a given pH
$E^\circ_\ce{Cu^2+|Cu} = \pu{0.34 V}$.
What will be reduction potential at $\mathrm{pH} = 14$ for the same couple?
Given that $K_\mathrm{sp}$ of $\ce{Cu(OH)2}$ is $10^{-19}$.
My Attempt
I think ...
- 292