All Questions
Tagged with equilibrium electrochemistry
47
questions
1
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Iodine/iodide electrochemistry help
I have an electrochemistry experiment with iodine in solution.
I am initially wanting to quantify the iodide in solution and extrapolate the concentration of I2(aq) and I3-(aq) in solution from this ...
0
votes
1
answer
126
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How does cell potential change with temperature for positive enthalpy and negative entropy?
A recent United States National Chemistry Olympiad question asked:
A certain voltaic cell has a standard cell potential that increases with increasing temperature. Which best explains this ...
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-2
votes
1
answer
124
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Inconsistency in between Nernst Equation and Gibbs Free Energy Equation [closed]
Part 1 - Derivation of the Gibbs Free Energy Equation: [copied from this]
Using the fundamental equations for the state function (and its natural variables):
\begin{align}
\mathrm{d}G &= -S\...
4
votes
2
answers
804
views
Acid dissociation constant from conductometric data
$\ce{0.007 M}$ aq. solution of anilinium hydrochloride had molar conductivity equal to $\pu{119.4 S cm2 mol-1}$, which became $\pu{103 S cm2 mol-1}$ when a few drops of aniline were added to the ...
- 828
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
1
vote
1
answer
768
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Why is the theoretical value of the electrode potential different to the experimental value for Cu and Al for a galvanic cell by using Nernst equation
I've construct a galvanic cell with the Al strip putting in the Aluminum nitrate solution and Cu strip putting in the CuSO4 solution. KNO3 is used as the salt bridge in this experiment. The question ...
- 11
0
votes
1
answer
564
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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
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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
-3
votes
1
answer
71
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Voltaic cell equilibrium confusion
In a voltaic cell, taking one with $\ce{Zn}$ and $\ce{Cu }$ electrodes for an example, an EMF is formed because the equilibria at the $\ce{Zn}$ electrode is shifted more towards the $\ce{Zn^2+ + 2e-}$ ...
- 126
2
votes
0
answers
165
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How do the assumptions of the Nernst equation impact its accuracy?
I was just wondering what impact the assumption that the equilibrium membrane potential for an ion is dependent on just the ion itself (if it is the only thing that is permeable). For instance, if I ...
- 21
0
votes
1
answer
170
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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
1
vote
0
answers
1k
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Why does the reaction between copper(II) ion and iodide ion proceed even though the E_cell of the set up is negative?
(iii) Another example of a reaction that does not agree with the theoretical prediction is the reaction between $\mathrm{Cu}^{2+}$ and $\mathrm{I}^{-}$ according to the equation below.
$$
2 \mathrm{Cu}...
2
votes
1
answer
318
views
Relation between standard silver-silver chloride electrode potential and solubility product of silver chloride
I learned that $E^\circ_\ce{Cl^-|Ag,AgCl}, E^\circ_\ce{Ag^+|Ag}$ and $K_\mathrm{sp}$ of $\ce{AgCl}$ are related as
$$\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, $$E =E_\circ - \dfrac{RT}{F}\ln\left(\dfrac{\ce{[X+]}} {\ce{[Y+] }} \...
- 750
1
vote
1
answer
221
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Why is "activity" of gaseous component equal to its partial pressure but that of aqueous component its concentration?
While solving an electrochemistry problem I had to calculate the reaction quotient of this reaction:
$$\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
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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
$$Q = \frac{(a_\ce{...
- 1,241
2
votes
2
answers
2k
views
Origin of electrode potential and its connection with electric double layer
Recently, I was learning about electrode processes and I came across the topic of "electrode potentials".
I understood that at equilibrium, a potential difference was generated at the ...
- 221
0
votes
0
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29
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Can I mix pressures and concentrations when finding equilibrium constant? [duplicate]
In order to find the equilibrium constant (or reaction quotient) I know I can find the value as the products over reactants raised to coefficient exponents. But, in all of the problems I have had to ...
- 129
0
votes
2
answers
489
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How does current start to flow when galvanic cell is first connected?
Using the Daniell Cell as an example, where in the steady state we expect zinc to be oxidised and copper to be reduced spontaneously due to the overall reduction in Gibbs free energy, how does the ...
- 103
4
votes
1
answer
8k
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How is the formula of mean activity coefficient derived?
The mean activity coefficient is defiend as follows:
$$\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
1
vote
0
answers
91
views
Equilibrium cell potential question
In an attempt to wrap my head around the basics of electrochemistry I'm working my way through Wesley R. Browne's 'Electrochemistry' primer.
With regards to the equilibrium potential of an ...
- 31
2
votes
0
answers
110
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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 ...
0
votes
3
answers
2k
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Activities and molar concentrations
I would be really happy if someone would clarify the term "chemical activity" and its implications for me, and also how it is related to the concept of molar concentration. My textbook fails at ...
0
votes
1
answer
877
views
Nernst equation and equilibrium
I am currently stuyding electrochemistry, and recently I've stumbled upon a problem where one is supposed to calculate the concentration of Fe3+ ions after a solution containing Fe2+ was titrated ...
6
votes
2
answers
208
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Protons and osmotic potential
In a hypothetical enclosed membrane only permeable to water (including hydronium), where inside the pH is lower than the outside, would water move inside?
- 61
-1
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2
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566
views
Is there a quick way to approximate a logarithm in Nernst equation?
The problem is as follows:
In a galvanic cell the cathode is an $Ag^{+}(1.00\,M)/Ag_{(s)}$
half-cell. The anode is a standard hydrogen electrode immersed in a
buffer solution containing $0.10\,...
2
votes
3
answers
2k
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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
0
votes
2
answers
549
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Equilibrium of an electrochemical cell [closed]
I am quite new to the field. So try to figure out what is meant by the equilibrium state of an electrochemical cell?
Is it, where both half cells passing the same number of electrons to either side? ...
- 3
1
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0
answers
49
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Calculating Equilibrium Constant from Cell Potential at Nonstandard Temperature
I'm currently working on a problem for a general chemistry class.
This is the voltaic cell given in the problem:
$$\ce{Sn^4+(aq) + Cu(s) -> Sn^2+(aq) + Cu^2+(aq)}$$
$$E^\circ_{cell} = \pu{-0.21 V}$$...
- 21