# Tag Info

6

My understanding is that a redox couple is an unordered pair of two conjugate species This is conceptually perfect and there is no problem when we talk about electrode potentials of half cells because as I had mentioned in your earlier queries, the electrode potential value and its associated sign do not know nor care how you write the half cell. What is ...

5

Moist air, rich in an electrolyte (salt particles) or human contact, providing both NaCl and H+ may supply the reagents needed for galvanic corrosion, with dissimilar metals in direct contact. This usually proceeds, albeit slowly, over time. Note, exposure to fruit juices could be especially problematic, resulting in a matter of days of continuous contact ...

4

From your comments it seems that you are looking for an approximation of a log. I wish you clarified that in the main question without mentioning calculators. It seemed you just wanted to avoid a calculator for some unknown reasons. As Poutnik states, anyone who can post here, will certainly have access to computers and hence the ability to calculate logs. ...

4

The electrochemical stability window is most important when considering components of an electrochemical system that you do not want to be oxidized or reduced. This refers most often to the electrolyte or protective coatings. For example, in lithium ion batteries it is highly desirable that the electrolyte does not react/change/degrade in any way as a ...

4

Your question is a valid question, and ignore downvotes. They don't mean anything. Your understanding is very good and that you realized that the electrode potential is a property of the electrode and it really does not care how the reaction is written. However, a equation is $needed$ to keep track of the electrons lost or gained in the Nernst equation. So ...

3

If it is maintained in air, no corrosion will happen. If it is maintained in water, and specially in salty water, the bronze part of the ring may be oxidized and will darken. Golden parts will not be modified.

2

Bard and Faulkner are outstanding electrochemists, but that potentiostat figure always annoys me because it makes it seem as though current flows through the reference electrode and that the working electrode is literally grounded. In reality, the reference electrode should conduct extremely low currents (pA, really) and the current through the working ...

2

I guess you are confused by the word window, just like a window has a limited opening [=in a loose sense an interval], electrochemical stability window means the range where the solvent does not get oxidized or reduced. As explained by CH3M, you cannot scan water past 1.2 V vs SHE. It will begin to decompose electrolytically. Of course you have to see the ...

2

This is a rather unusual case of what is discussed in answers like this one, where we circumvent problems with multiple atoms being oxidized or reduced by considering whole compounds as oxidizing or reducing agents. Here, the whole-compound redox-active material is $\ce{CrO5}$, and as in peroxide disproportionations generally this is both an oxidizing agent ...

2

Padé Approximation for ln(1+x) provides very interesting trade off between simplicity and accuracy ( See also Wikipedia - Padé approximant ): $$P\{ \ln( 1+x ) \} = \frac{x(6+x)}{6+4x}$$ $\ln(1) = 0$, $\ln(2) = 0.7$, $e_\mathrm{max} = 0.00685$, $e_\mathrm{max, rel} \lt 1\%$, $e_\mathrm{RMS} = 0.00258$ This is already a good and fast ...

2

No, electrodes do not know about each other. When an electrode is inserted to an electrolyte, the electrochemical reaction is ongoing in both directions. If reduction direction overruns oxidation, the potential of the electrode is increasing ( or vice versa ) until the rate of both reaction gets equal, the net reaction rate is zero and the electrode reaches ...

2

I've found a answer for my question from this question. The way to compute the conductivity of electrolyte with multiple ion types is given from the work Pawlowicz, Rich, ( 2008), Calculating the conductivity of natural waters, Limnol. Oceanogr. Methods, 6, doi:10.4319/lom.2008.6.489. For general case consider the system, which consist of $N_+$ number of ...

1

In my understanding, by energy/power decoupling is here meant the possibility of independent scaling up of the available sustained battery power and the possibly stored energy. For normal batteries of electrochemical cells, regardless of their chemistry, scaling up increases both battery power and energy in more or less comparable rate. But for redox flow ...

1

I'm not sure of any conventional ways of electroplating selenium, but you could use a technique such as magnetron sputtering to spray a thin film of selenium onto another metal. Heck, you could even use glass or wood if you wanted to do it that way. And if you're going for thin, this technique can get you some of the thinnest, smoothest layers of metal out ...

1

Perhaps a simple example will illustrate how a solubility product constant, $\ce{K_{sp}}$, may be determined via measurement of an appropriate voltaic cell potential. Consider the estimation of the $\ce{K_{sp}}$ value for the following equilibrium: $$\ce{AgCl(s) <=> Ag+(aq) + Cl-(aq) \quad K = K_{sp}} \tag{1}$$ This equilibrium lies far to the left ...

1

It is a complex problem. Yes, NaCl solution is a conductor, so electricity will pass through the solution. Now in your situation both electrode are made of copper. Since electricity is passing through the solution, electrolysis must occur at both electrodes. You cannot have electrolysis only at one electrode. Assuming there is sufficient salt in the ...

1

For an electrochemical reaction, you count the atoms / ions by mol, and use the coulomb as a counting unit of charge. For a more intuitive explaination of the $n$ factor in the Faraday equation, try this analogy: The summer olympics include swimming in a pool with lanes $50\,\pu{m}$ long. Among the typical competitions are runs about $50$, and $100\,\pu{m}$...

1

The equilibrium reaction for the auto-dissociation of water is: $$2\text{ H}_2 \text{O}(l) \leftarrow \rightarrow \text{H}_3\text{O}^+(aq) + \text{OH}^-(aq)$$ The associated equilibrium constant $K_w$ is: $$K_w=[\text{H}_3\text{O}^+]\times [\text{OH}^-] \approx 10^{-14}$$ (Strictly speaking the expression is: \frac{[\text{H}_3\text{O}^+]\times [\text{OH}^-...

1

The chlorate system is very complex. I doubt that the open-circuit potentials can be actually measured in solution, but rather are calculated from heats of formation. If the term "oxidizing strength" is used to compare systems, it should be rigorously defined; in this case, it seems that "oxidizing strength" is defined as "open-circuit voltage". But this ...

1

To prepare copper acetate absence H2O2, employ a known method from hydrometallurgy to process copper ore employing aqueous ammonia, air (a source of oxygen) and a small amount of salt (acting as an electrolyte for this, in part, spontaneous electrochemical reaction detailed below). This results in tetra-ammine copper hydroxide. The latter exists only in ...

1

I don't know why your textbook author is confusing and still teaching American & European conventions. It is obsolete now. I will show you how oxidation potentials were quoted by American electrochemists in the 1950s-60s. Have a look at the table Latimer's book: Oxidation States of the Elements and their Potentials in Aqueous Solutions pg 340. This was a ...

1

Suppose you have two galvanic cells A and B producing 1.14 V. If you connect them together, with both positive poles together, and both negative poles together, nothing will happen. No current will be produced. Now suppose that one of these two cells, say A, produces the same voltage 1.14 V, and B produces a little less than A, say 1.10 V. A works in a ...

1

k0 has units of frequency (1/time) All concentrations are surface concentrations (mol/area) Sometimes people use k0 with units length/time and volume concentrations (mol/volume) On Wikipedia: Coxy stands for Ox concentration * at equilibrium *. Cred stands for Red concentration * at equilibrium *. It's for 1 electron. Multiply by n for n electrons. On ...

1

I think Bard's is more general than Newman's, Newman's assumes Cx=Cx* where Bard does not. Bard says the current is proportional to the forward rate, and if there are metal ions near the electrode, the forward reaction removes electrons from the electrode to reduce the ions. That means the current flows into the electrode. Bard then says the applied ...

1

More on the mechanics of the interaction of nitric acid with transition metals, to quote a related source on the electrolysis introduction of solvated electrons into HNO3 in place of via oxidation of copper: $\ce{Cu -> Cu(I) + e-}$ $\ce{Cu(I) -> Cu(II) + e-}$ One major synthetic process for hydroxylamine is the hydrogenation of HNO3 on a ...

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