# Tag Info

## New answers tagged electrochemistry

0

While yes, for AgCl, a small amount could dissolve per the reactions $\ce{AgCl(s) <=> Ag+(aq)+Cl−(aq)}$ $\ce{AgCl(s) + Cl−(aq) <=> AgCl2−(aq)}$ However, I believe the presence of the AgCl as a suspension would have an impact on conductivity per this source, as well, where AgCl particles replace Al2O3–H2O per the abstract below: In this ...

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What you are missing is understanding of general nature of redox reactions. Redox reactions need two half reactions to complete. You can't arbitrarily select these two half reactions. They has to be chosen as instructions given in the problem. For example, for your given problem, it should be noted the medium of the reaction, whether it is acidic or basic or ...

1

I'm a bit puzzled by the phrase "AgCl solution," since there wouldn't be a solution but rather colloidal size particles of AgCl in the aqueous solution. I don't think you could have a bottle of colloidal size particles of AgCl since once dried the particles would stick together in a lump. For AgCl, a tiny amount would dissolve hence there would be ...

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For the reaction: $$\ce{6I- (aq) + 4 H2O + 2 MnO4- (aq) ->[excess I-] 3 I3- + 2 MnO2 (s) + 8OH-}$$ what you are missing is the Nernst Equation. The two reduction half cell reactions are: $$\ce{I3− + 2e- <=> 3I− \quad\quad EMF = +0.53}$$ $$\ce{MnO4− + 2H2O + 3e− <=> MnO2(s) + 4 OH− \quad\quad EMF =+0.595}$$ The gist of the Nernst ...

-1

First, I would not frame deviation in voltage are 'errors' as energy is not being lost, but otherwise converted (to heat, for example). I cite a source: In practice, passage of any finite amount of electricity results in a certain degree of irreversibility as some of the electrical energy is dissipated as joule heat in the internal resistance of the cell, ...

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I have used the preferred MathJax notation, you can see it is much simpler and compact: $$\ce{6I- (aq) + 4 H2O + 2 MnO4- (aq) -> 3 I2 + 2 MnO2 (aq) + 8OH-}$$ You can see both iodides and permanganates carry a negative charge while their spent forms are neutral. This negative charge must be passed to other anions and there are not but hydroxide anions ...

1

There are 2 cases: If the formula of the theoretical model is known, the approximation follows this formula to determine the formula parameters. If there is no theoretical model, or the model is not followed, then reasonable empirical formulas are tested and the best fitting and simple enough is chosen. Aside of polynomials and logarithms, interesting ...

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In addition to price advantage, CuSO4 also provides a source of sulfate ions, which are relatively stable. The sulfate anion is also a known scavenger of radicals that may be present in the solution. For example, a reaction between sulfate and the hydroxyl radical (a possible electrolysis product): $\ce{SO4^{2-} + .OH -> .SO4^- + OH^-}$ And, the ...

1

You need to look for the data in a different way. You can use electrical conductivities to get the current flow the solution. From the imagined current flow you calculate how much hydrogen would be generated.

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Alejandro, you are right, the electrolytes will make a difference. The difference is not in terms of hydrogen production per se, as Maurice mentions in the comments, it will be in terms of energy saving. Electrolytic reactions are "exact" in the sense that if 100 electrons reach the electrode from a battery, 100 hydrogen ions will be reduced. In other words, ...

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I did find a work, 'Electrolyte Engineering toward Efficient Hydrogen Production Electrocatalysis with Oxygen-crossover Regulation under Densely Buffered Near-neutral pH Conditions', with comments of interest. I start with some background from the introduction: In recent decades, drastic progress in solar fuel production has occurred: photovoltaic cells ...

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

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 ...

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Another way of describing the electric behavior of the electrode is to state that when dipped in water, one Zn atom quickly looses two electrons and gets dissolved in the solution. The electron remains in the metal and prevents any second Zn atom from bringing more electrons in the metal. Simultaneously the solution gets positively charged and the first $\ce{... 2 No, electrodes do not know about each other. When an electrode is inserted to an electrolyte, the electrochemical reaction is ongoing in both directions. If reduction direction overruns oxidation, the potential of the electrode is increasing ( or vice versa ) until the rate of both reaction gets equal, the net reaction rate is zero and the electrode reaches ... 2 This is a rather unusual case of what is discussed in answers like this one, where we circumvent problems with multiple atoms being oxidized or reduced by considering whole compounds as oxidizing or reducing agents. Here, the whole-compound redox-active material is$\ce{CrO5}$, and as in peroxide disproportionations generally this is both an oxidizing agent ... 0 I found a 2019 source work on Chromium peroxide. To quote the key preparation equation: Chromium peroxide (Cr(O2)2.H2O or brieﬂy CrO5) is an extremely potent oxidant. This compound is a product of the following reaction:$\ce{(NH4)2Cr2O7 + 4 H2O2 + 2 H+ -> 2 Cr(O2)2.H2O + 4 H2O + ammonium salt}$(1) Here are associated corresponding comments ... 0 Without taking oxidation numbers into account, I have first balanced the Cr atoms, then the H atoms, and finally the Oxygen atoms. And I have found :$$\ce{4CrO_5 + 12 H^+ -> 4 Cr^{3+} + 7 O_2 + 6 H_2O}$$ With the sulfate ions it gives : $$\ce{6 H_2SO_4 + 4 CrO_5 -> 2 Cr_2(SO_4)_3 + 7 O_2 + 6 H_2O}$$ 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 ... 0 Based largely on a prior answer to the question: 'Why is it important to use a salt bridge in a voltaic cell? Can a wire be used?', the explanation centers on maintaining the charge balance (electrical neutrality) of the battery cell. The electrons are efficiently transported via the electrodes connected by wires as sourced from the half-cell:$\ce{Zn -&...

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 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 ...

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One can also say that any equilibrium constant $K$ is related to the change of free enthalpy ${\Delta G°}$ of the particular reaction : $${\Delta G° = RT lnK}$$ And this ${\Delta G°}$ does not depend on any other compound present in the solution.

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More than 50 years ago, Pauling has also observed this regular tendency observed among the different chlorinated acids. But he suggested that it may be due to a tendency to get the highest possible number of Cl-O bonds. The oxidative power could depend on the number of free doublets around the chlorine atom. Perchlorate has no free doublet : it is not a good ...

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: $$\frac{[\text{H}_3\text{O}^+]\times [\text{OH}^-... 0 IUPAC defines the electrode potential of an electrode to be the EMF of a cell in which the electrode in question is on the right hand side of the line representation of the cell and a SHE is on the left hand side. As such, the electrode potential of the M^+/M couple is E^o_{M^+/M} = \phi_{M} - \phi_{R} where R refers to the reference electrode, in ... 4 From your comments it seems that you are looking for an approximation of a log. I wish you clarified that in the main question without mentioning calculators. It seemed you just wanted to avoid a calculator for some unknown reasons. As Poutnik states, anyone who can post here, will certainly have access to computers and hence the ability to calculate logs. ... 2 Padé Approximation for ln(1+x) provides very interesting trade off between simplicity and accuracy ( See also Wikipedia - Padé approximant ):$$P\{ \ln( 1+x ) \} = \frac{x(6+x)}{6+4x}$$\ln(1) = 0, \ln(2) = 0.7, e_\mathrm{max} = 0.00685, e_\mathrm{max, rel} \lt 1\% , e_\mathrm{RMS} = 0.00258 This is already a good and fast ... 1 To prepare copper acetate absence H2O2, employ a known method from hydrometallurgy to process copper ore employing aqueous ammonia, air (a source of oxygen) and a small amount of salt (acting as an electrolyte for this, in part, spontaneous electrochemical reaction detailed below). This results in tetra-ammine copper hydroxide. The latter exists only in ... 2 I've found a answer for my question from this question. The way to compute the conductivity of electrolyte with multiple ion types is given from the work Pawlowicz, Rich, ( 2008), Calculating the conductivity of natural waters, Limnol. Oceanogr. Methods, 6, doi:10.4319/lom.2008.6.489. For general case consider the system, which consist of N_+ number of ... 1 Perhaps a simple example will illustrate how a solubility product constant, \ce{K_{sp}}, may be determined via measurement of an appropriate voltaic cell potential. Consider the estimation of the \ce{K_{sp}} value for the following equilibrium:$$\ce{AgCl(s) <=> Ag+(aq) + Cl-(aq) \quad K = K_{sp}} \tag{1}$$This equilibrium lies far to the left ... 0 The standard half cell potential, \mathrm{E^0_{red}}, is for a 1.000 molar solution for the ion being reduced. For other concentrations the Nernst Equation gives the half-cell potential, \mathrm{E_{red}}.$$\mathrm{E_{red}} = \mathrm{E^0_{red}} - \dfrac{\mathrm{RT}}{\mathrm{zF}}\ln{\dfrac{a_{\mathrm{Red}}}{a_\mathrm{Ox}}} Note that the Nernst equation ...

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 ...

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 ...

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 ...

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 ...

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 ...

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.

0

Per a source, the chemical reactions in a zinc–carbon battery can be detailed as follows, to quote: In a zinc–carbon dry cell, the outer zinc container is the negatively charged terminal. The zinc is oxidised by the charge carrier, chloride (Cl−) via the following half reactions: Anode (oxidation reaction, marked −) $\ce{Zn + 2 Cl− → ZnCl2 + 2 e−... 4 Your question is a valid question, and ignore downvotes. They don't mean anything. Your understanding is very good and that you realized that the electrode potential is a property of the electrode and it really does not care how the reaction is written. However, a equation is$needed\$ to keep track of the electrons lost or gained in the Nernst equation. So ...

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 ...

0

There is a field of chemistry/metallurgy that uses applied potential to measure corrosion response of metals in various solutions : lookup Pourbaix Diagram. There are many books on the topic. ( My excuse for not posting this a year ago is that hydrogen stress cracking is my favorite subject and I got distracted.)

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

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 ...

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