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Questions tagged [electrochemistry]

The branch of chemistry that deals with the study of redox reactions and how they can be applied to generate electricity (in electrochemical cells) and to carry out non-spontaneous reactions using electricity (electrolysis).

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Some questions about electrochemistry

1) Which of the following electrodes is used as pickup electrode for measuring redox potential of the system Cr3+/Cr2+? a) glass. b) zinc. c) copper. d) platinum e) silver chloride 2)...
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Cheaper ionic membranes

I am trying to make sodium hydroxide by electrolyzing table salt. I learned that I need cation exchange membrane (CEM) to prevent Cl- from crossing over to the cathode. The only example of CEM that I ...
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How do you use the Nernst equation on lithium ion batteries [on hold]

Anode: LiC6<=> C6 + Li+ + 1e- Cathode: Li+ + 1e- + CoO2 <=> LiCoO2 Overall: LiC6+CoO2<=>C6+LiCoO2 How do you apply the Nernst equation to this reaction? The concentration of solids is ...
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How Can I Induce Corrosion Electrochemically?

I'm very interested in measuring corrosion in metal alloys, particularly in salt solutions. I understand metals corrode over time, however, I was wondering if it's possible to electrochemically "speed ...
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Electrochemistry: Voltage, solution resistance, current/m3 & designing a supply to maintain perameters

As it would seem current density is affected by several factors. Electrode Ae, electrolyte concentration, electrolyte conductivity, etc.. I'm conducting a series of experiments involving the ...
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what is the difference between oxidation state, charge and valency? [duplicate]

Is there any specific atom or compound or molecule possessing oxidation state different from charge and valency, so that we can clearly understand the difference between the three.
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Pale blue species forming during electrolysis of NaHCO3

I have a solution of 3500 ml $\ce{H2O}$ + 454 g $\ce{NaHCO3}$ in electrolysis at a potential of 12.5V using a lead anode and copper cathode. The surface areas aren't measured but they are enormous. I ...
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What material is my pot and what is coating it please?

I have a large beaten metal pot I inherited from my parents. It was kept outside and entirely tarnished black, except for places in the inside which had a gold appearance (it's obviously not a gold ...
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Equilibrium constant kp or kc? [on hold]

In electrochemistry , nerst equation we use logkc if chemical species are in solution form but if gases then we use logkp. But kp and kc are different emf of cell will come out to be different by ...
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Is this the right way to make a diy battery? [on hold]

I know that batteries run off redox reactions. Therefore can I choose an arbitrary reduction reaction in one half cell, an arbitrary oxidation reaction that will happen at room temperature for the ...
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Is it possible to convert a combustion reaction directly into an electrochemical one?

I'm fairly inexperienced in chemistry so forgive me if this question is silly but, why is it not possible to convert a combustion reaction to an electrochemical one directly and harvest the electrical ...
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Will there be electrical conductivity when two platinum metal strips are connecting with hydrochloric acid? [closed]

In the following set-up, the bulb does not light up. Which of the following changes may light up the bulb? (1) Replacing platinum electrodes with silver electrodes (2) Replacing silver chloride powder ...
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Electrolytic cell to remove soft solder from silver?

Hi my chemistry is pretty dire but have vague idea that an electrochemical cell could be used to remove soft solder (lead/tin probably) from a piece of sterling silver in need of a repair. The ...
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41 views

Why do power requirement figures for water electrolysis on the web seem to be wrong?

I need to calculate the power needed to electrolyse 1 mole of water for a project. We will either use Polymer Electrolyte Membrane Electrolysis or Alkaline Water Electrolysis, they operate on 1.75V-2....
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47 views

Why is concentration of nickel nitrate constant? [closed]

Consider a cell with both nickel electrodes and a solution of nickel nitrate ($\ce{Ni(NO3)2}$). Current is passed through the solution. The $ E° $ values predict that nitrate in the solution should ...
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Entropy of lead storage cell

I am having trouble with calculating the entropy of a lead storage cell. The standard cell potential is given as $\pu{2 V}$ and the standard enthalpy change is $\pu{-306 kJ}$. I found out the Gibbs ...
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Working principle of simple chemical cells

I have just learnt about simple chemical cells but I have no idea how to determine which cells will work and which will not and the working principle of those cells. I know that a chemical cell with $...
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47 views

Half-Reactions of Hydroxide [closed]

The following is the equation I have: $$\ce{Ca(s) + 2H2O(l) -> Ca(OH)2 v + H2 ^}$$ I am tasked to write the half-reaction equations for both the oxidation and/or reduction process. So, currently ...
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Can ZnO act as a reducing agent for noble metals like Pd?

Palladium ions (e.g., $\ce{Pd^2+}$) can be reduced to $\ce{Pd}$ by more reactive metals such as zinc. Metal oxides such as $\ce{ZnO}$ are very stable but can its atoms in the oxide structure still be ...
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Do We change sign of electrode potential when reversing an equation?

I have a cell equation as: $$\ce{2Cr^0 + 3Cd^2+ -> 2Cr^3+ + 3Cd^0}$$ I am provided the standard reduction potentials as: $$\begin{align}\ce{Cd^2+ + 2e- &-> Cd} && E= \pu{-0.4V}\...
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Half-reaction for ammonium nitrate comproportionation into dinitrogen monoxide.

Ammonium nitrate comproportionates into dinitrogen monoxide in the following reaction: $\ce{NH4+ (aq) + NO3- (aq) -> N2O(g) + 2H2O (l)}$ I attempted to write the half-reactions by calculating ...
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Basics of the electrical double layer

I am currently trying to gain a better understanding of the use of electrochemistry in the field of organic synthesis. In order to better understand these syntheses I thought it would be a good idea ...
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Calculating the standard reduction potential for the oxidation of water

I was working with Latimer and Frost diagrams for oxygen when I came across what seems to me a contradiction. From the Latimer diagram for oxygen below, we know the standard reduction potential for ...
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In the Nernst equation, does T refer to the temperature of the standard cell or the cell under non-standard conditions?

I am doing an experiment where I am varying the temperature of the electrolyte of the anode half cell. I am trying to calculate the cell potential using the Nernst equation under standard conditions ...
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Does electrolysis of aqueous tin (II) chloride produce Cl2 or SnCl4? Or both?

When applying a current to an aqueous solution of tin (II) chloride, tin crystals grow from the cathode. However, I'm not sure about the anode. It seems like there are two possible reactions: $$\ce{...
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Equivalent conductivity of barium chloride at infinite dilution

Find out the equivalent conductivity of barium chloride at infinite dilution given that the ionic conductivities of $\ce{Ba^{2+}, Cl-}$ are $\pu{127 ohm^-1 cm^2 equivalent^-1}, \pu{76 ohm^-1 cm^2 ...
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How to Separate Copper Nanowires in an Alumina Membrane

So, in my Chemistry Lab we had an experiment to use Whatman alumina membranes and GaIn eutectic to create Nickel nanowires through electrodeposition. So essentially Nickel wire electrode and alumina ...
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Why electrons are attracted by cathode in Voltaic/Galvanic cell

I studied that in the above setup electrons are attracted by Cu because of their reduction potential but they don't involve in reaction because of the d-bands of the electronic structure so Hydrogen ...
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Does the Nernst equation suggest voltaic cell voltage remains constant over time?

Say the following reactions are occurring in my voltaic cell: $$\ce{Mg->Mg^{2+} + 2e- +2.36V}$$ $$\ce{Cu^{2+} +2e-->Cu -0.34V}$$ Then, the Nernst equation would become: $$E_{cell}=2....
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35 views

Why is the current draw dropping in water electrolysis

We've done an experiment regarding water electrolysis. Basically, we just separated the oxygen and hydrogen gas in a beaker that contains a magnesium sulfate solution. We set the power supply voltage ...
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47 views

Using a significantly large metallic sphere, could we draw out the electrons from the negative terminal of a battery?

I've pored over many articles on electrochemical cells, and I understand that on the oxidation side of a zinc-copper Daniell cell, the anode is highly negatively charged because zinc participates in ...
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Troubleshooting electrochemical batteries

For my science classes, I have built multiple types of electrochemical batteries utilizing oxidation-reduction reactions, and I have demonstrated that they each produce potential difference across the ...
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How does an electrolyte conduct electricity at low potential?

My understanding is that electrolytes conduct electricity by: 1) movement of ions, the negative ions migrate to the positive electrode and vice versa. This is however not enough, if these ions just ...
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Couldn't make nickel acetate solution using the same process as copper acetate

I'm trying to electroplate nickel on a copper-plated piece of stainless steel. To electroplate the piece with copper, I put two copper electrodes in a vinegar (5% acetic acid) and NaCl solution (~1 g/...
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What determines the potential of an unpoised electrode?

Suppose you have a piece of gold electrode placed in an aqueous solution with negligibly few gold ions. The Nernst equation is not applicable in this situation because there is no thermodynamic ...
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Is it possible to generate electricity by using two inert electrodes in a galvanic cell?

The Daniell cell has two active electrodes, meaning that both the copper and the zink electrodes participate in the redox reaction. However, in a lemon battery for example, the copper electrode is ...
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What is the electrode potential at the equivalence point if concentrations of titrant and titrand are going to be zero?

Let's assume that the titrand is $\ce{Fe^2+}$ and the titrant is $\ce{Cr2O7^2-}$. Then $$E = E^\circ_\ce{Fe^{2+}/Fe^{3+}} - \frac{RT}{nF}\ln\frac{\ce{[Fe^{2+}]}}{\ce{[Fe^{3+}]}}$$ $$E = E^\circ_\ce{...
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Does anything get precipitated in the half cells during the action of a salt bridge? [duplicate]

In the Zn/cu cell, once the reaction starts, excess ions begin to accumulate in both the half cells. To maintain the electrical neutrality, a salt bridge is used. how does the salt bridge actually ...
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54 views

what should be the onset potential using cyclic voltammetry?

I am working for PEM fuel cell cathode material. I am confused regarding the onset potential determination for my catalyst (CV attached, fig 1 is complete CV while fig 2 is its zoom image for clear ...
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1answer
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Bonding metal pieces using electroplating - what's the process called?

So I think the title all most says it all - given say two pieces of copper can we make solid 'weld' using electroplating chemistry? If so whats the accepted terminology for this process so I can do ...
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Can a car's battery be used as a sacrificial anode?

The title of the question says it all. Can I hook the anode of my car's battery up to the car's shell and prevent it from rusting? Also would the car's battery get electrically charged from this?
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Why can't sulphate ion be discharged in the anode of electrolysis?

Given that there is an aqueous solution of sulfuric acid ($\ce{H2SO4}$), $\ce{2H+}$ is reduced in the cathode and $\ce{OH-}$ is reduced in the anode. Why is $\ce{OH-}$ preferentially discharged over $\...
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1answer
60 views

Confusion about the relation between gibbs free energy and electromotive force

$$\Delta G = -nFE$$ My textbook says that we can measure that this $\Delta G$ is measured when the work is done reversibly. But my confusion is how will we work reversibly when we have an ...
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1answer
36 views

Does concentration remain constant in an electrochemical cell's half cells?

We have from Nernst equation: $\mathrm{E_{cell} = E^\circ - \dfrac{RT}{nF} \ln Q_c}$ But I was wondering that in a simple cell like Daniel cell if concentration of $\ce{Zn^{2+}}$ keeps increasing ...
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130 views

Faraday's Law of Electrolysis problem

Question: How many moles of iron will by passage of $\pu{4 A}$ of current through $\pu{1 L}$ of $\pu{0.1 M}$ $\ce{Fe^{3+}}$ solution for $1$ hour. Assume $\ce{Fe^{2+}}$ is not present in the ...
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1answer
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What drives the redox reactions in a standard hydrogen electrode?

In this video, the SHE half cell has two redox reactions occurring i.e. $$\ce{2H+ (g) + 2e- <=> H2 (g)}\\ \ce{H2 (g) <=> 2H+ (g) + 2e-}$$ But how can a single half cell initiate the two ...
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1answer
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Number of electron for complete Discharge [closed]

What is the answer for question 17 and what is mean by "number of electrons for complete discharge?" Which of the following needs the largest number of electrons for complete discharge during an ...
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1answer
59 views

How&why does change in concentration affect cell potential

I'm a bit confused about why (in 1c) if the air pressure is lower, and there is a lower concentration of oxygen, why the cell potential decreases. It checks out fine with the Nernst Equation, but ...
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1answer
54 views

Electrochemical cells. Why is a salt bridge needed at all when the system is open? [closed]

I get that the purpose of salt bridges is maintaining the amount of negative and positive charges in the solutions of two connected half-cells when electrons flow from one to the other. But when the ...
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1answer
43 views

Current in a Lithium Ion Battery

I am trying to find the current transferred to the anode and cathode of a Lithium Ion Battery at different voltages. I know the temperature (approximately) of the battery, the battery's starting ...