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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5
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1answer
2k views

How to calculate the potential via Hess's law? Is my textbook wrong about this?

Given the two reduction half-reactions for the following fuel cell, determine the standard cell potential $E^\circ_\mathrm{cell}$, $$\ce{CH4 (g) + 2 O2 (g) + 2 OH- (aq) -> CO3^2- (aq) + 3 H2O}.$$ ...
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1answer
30 views

Why are dendrites formed during dilute CuSO4 electrolysis black?

During the weekend, I wanted to conduct a kid's experiment - the copper dendrite formation. I was (partially) successful and now I would like to know what went wrong. The procedure was taken from the ...
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1answer
25 views

Reduce potential by adding NaOH. With solubility

Ff I don’t know how to calculate c part.. What I did is: E=E* - RT/nF lnQ Ks(cuoh2) = [cu][oh]^2 So we can know how much concentration of cu has to be eliminated and with that we can calculate the ...
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18 views

Copper doesn't stick during electroplating

I feel so stupid and doesn't even know what to do. I want to form a thin metallic film or plate on the graphite cathode. In the beginning of the plating process, the copper deposited a very very thin ...
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2answers
1k views

Nernst equation for a fuel cell when gases are stored separately

I have run some tests with a PEM fuel cell and the voltage we have found was $1.44\ \mathrm{V}$. Given that the standard potential for a fuel cell is $1.229\ \mathrm{V}$ what is causing the difference ...
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1answer
41 views

How does Fe2+ become Fe in sacrificial protection? [closed]

I've searched low and high on the internet, but nothing to help me. I know that zinc is oxidised in preference to iron, and that it "donates" those two electrons to iron. $$\ce{Zn -> Zn^2+ + 2e-}$$...
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1answer
23 views

Electrochemistry - Understanding Diffusion Potential

I have a big problem trying to wrap my head around this for several hours and I cannot seem to make sense of it. I have to link this scheme with the 3 colored potential profiles on the bottom of the ...
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21 views

Why does changing the salt of the salt bridge effect the voltage produced in a galvanic cell?

My experiments results showed that the voltage decreases down $\pu{Group 1}$: $\ce{Cl-}$ salts in the salt bridge. All other variables were kept constant. $\ce{Zn}$ and $\ce{Cu}$ rods were used. ...
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1answer
58 views

Copper electrode in a daniel cell

Suppose I have a beaker containing $\ce{CuSO4}$ solution and I dip $\ce{Cu}$ rod in it.Now my question is what reactions are going to take place? Is the $\ce{Cu}$ rod going to acquire any positive ...
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1answer
123 views

Why does magnesium deposit during electrolysis of a molten mixture of MgI2 and AlBr3?

During the electrolysis of mixed salts, I read, and was taught, that the cation with a higher ionization energy would deposit at the cathode. I was also told that you cannot use the standard electrode ...
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1answer
31 views

Applied Potential and Electrochemical Cell Potential

Electrolysis of molten lithium hydroxide at $\pu{750 K}$ to form lithium metal $$\ce{4 LiOH -> 4 Li + 2 H2O + O2}.$$ Electrolysis will only proceed at an appreciable rate when the applied ...
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48 views

Relation between reactivity series and electrochemical series [closed]

I have already read answers to the following questions: Reactivity series of metals What is the difference between reactivity series and electrochemical series? But I didn't get what I wanted. When ...
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1answer
43 views

Find pH and Kw for water with given values of conductivity

At $\pu{25 ^\circ C}$, $\lambda_\infty (\ce{H+}) = \pu{3.5 \times 10^{-2} S m2 mol-1}$ and $\lambda_\infty (\ce{OH-}) = \pu{2 \times 10^{-2} S m2 mol-1}$. Determine $\mathrm{pH}$ and $K_\mathrm{w}$. ...
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32 views

For this experiment on cyclic voltmmetry, the more positive current is on the ___________ side of the y-axis of the graph [closed]

The options for the answers are "left", "bottom" and "top". I am stuck in between 'left' or 'top' as the answer. I would appreciate some help and thanks in advance! :)
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2answers
89 views

Is anode actually ever negative?

Disclaimer: This question comes from a physics student. I was studying electrostatics and I was wondering how to charge a conductor at home without any fancy furs etc. So an idea came to me: take a ...
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1answer
244 views

Does a zinc metal coating react with coffee in a coffee grinder?

I'm restoring an old coffee grinder and I want to give the grinder mechanism a nice zinc / silver coating. But I read it is not safe for zinc to be in contact with acidic foods. When I look at the ...
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0answers
34 views

Galvanic Cell Temperature Dependence

I'm currently studying the temperature dependence of the following cell: $\ce{Cu_{(s)} + 2Ag^{+}_{(aq)} <=> 2Ag_{(s)} + Cu^{2+}_{(aq)}}$ ($E^⦵ = \pu{+0.46 V}$) Experimentally, I recorded the ...
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1answer
33 views

electrochemistry experiment

something strange. i made an electrochemistry experiment in which i have measured the potential of cell: Ag, AgCl | (1M)KCl ║ [Fe(CN)6] 3-, [Fe(CN)6] 4- | Pt with different concentrations of Fe+2/Fe+...
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3answers
651 views

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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30 views

What is the yellow compound formed in electrolysis of brine?

Last week, I tried to conduct electrolysis of brine in my house using copper electrodes and 6V battery. After sometime, the entire solution turned orange/yellow. The yellow substance formed a kind of ...
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3answers
212 views

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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3answers
78 views

Electrochemistry conditions for voltage to increase in a galvanic cell

I understand that increasing the concentration of reactants in a galvanic cell generally causes the voltage of the cell to increase. But is that really the case always? Consider a standard cell of ...
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1answer
22 views

Is the thermodynamic stability against reduction/oxidation of an electrolyte dependent on the electrode material?

Consider an electrochemical cell with an inert Pt working electrode (WE) and some electrolyte that irreversibly decomposes upon oxidation. A minimum potential $E_{min}$ (vs. some reference) needs to ...
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1answer
21 views

How are cells rechargable?

I have learnt that you can test if a reaction is thermodynamically feasible by testing if the cell voltage $E_\mathrm{cell}$ is greater than $0$. Surely, if a reaction is feasible, then the $E_\mathrm{...
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1answer
848 views

In a galvanic cell, why does an electrode with a higher potential “pull” the electrons from the electrode with a lower potential?

I'm doing Grade 12 Chemistry and I'm unsure of this, taking the hydrogen electorde as having a potential of 0 volts. I'll use the copper-zinc cell as an example. Just let me know if I've got the full ...
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1answer
155 views

How do you calculate a half cell potential Copper(II) and Copper Sulfate?

I have to complete an experiment for school where I have copper and zinc electrodes placed into an electrolyte of copper sulfate and I have measured the potential across it at varying temperatures. ...
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2answers
39 views

Confusion regarding the positively charged copper electrode in a Daniell cell [closed]

Suppose I bought a newly manufactured Daniell cell then in this situation, can someone explain what all will be going on at the zinc and copper electrode? (Since it is newly manufactured and not used ...
3
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1answer
41 views

Can I anodize an aluminum coating on steel to have better corrosion inhibition for the steel?

I am planning to coat aluminum on steel and I want to give the steel its maximum corrosion protection. Is anodizing the coating necessary?
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1answer
32 views

Electrolysis of Baking Soda separated by semi permeable membrane

I have dissolved baking soda in battery water (de-ionized), in a glass beaker and used a food handling glove (vinyl) as a semi-permeable membrane to separate a graphite electrode from a copper ...
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0answers
19 views

How can you have a reduction potential for a non redox reaction?

The standard reduction potential for the half cell $$\ce{FeCO3_{(s)} + 2e- <=> Fe_{(s)} + CO3^2-} \quad\quad(E^o =-0.756 \text{V})$$ and the standard reduction potential for the half cell $$\ce{...
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2answers
34 views

clarification on background limits in electrochemistry

I’m teaching myself electrochemistry, and this question is from the general introduction of the book I’m using. According to Bard’s Electrochemical Methods book, in a given cell, the background limits ...
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3answers
65 views

Why is this reaction spontaneous in standard conditions?

To study if this reaction is spontaneous I proceed in this way: $$\ce{2H_{3}O^{+} +Fe ->H_{2} +Fe^{2+} + 2H_{2}O}$$ First I write the two semireaction: $$reduction: \ \ \ce{2H_{3}O^{+} +2e^{-} ->...
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0answers
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Oxidative phosphorylation analogue

Does the salt bridge in galvanic cells resemble the ATP pump in the inner mitochondrial membrane? And if yes than did someone use this pH difference in harvesting this energy?
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1answer
18 views

How does increasing the Hydrogen Concentration of CuSO4 (electrolyte) affect electroplating of copper

I'm trying to find an answer as to how lowering the pH of the CuSO4 solution during electroplating of copper affects the amount of copper deposited onto the cathode. My very basic understanding is ...
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1answer
39 views

Why oxidation potential of an electrode equals negative reduction potential of the same electrode?

My textbook states that: $E^\circ_\mathrm{ox} = -E^\circ_\mathrm{red}$ (of same electrode) I know that electrons flow from anode half cell (oxidation) to cathode half cell (reduction). But if $E^\...
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0answers
15 views

Competing half reactions in electrolysis of aqueous solution of sodium hydroxide

If you run a direct current using pure nickel electrodes through a solution of NaOH in distilled water, you will separate the water into hydrogen and oxygen. Are there any other reactions that could ...
2
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1answer
85 views

Would a salt bridge work through which the ions could not diffuse into the half cells?

Instead of covering the ends of the salt bridge in an electrochemical cell with a membrane, one could also plug them on both sides with a conductive non-porous material, for example gold, which doesn'...
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2answers
28 views

Way to confirm dichromate ion presence where other ions are messing with the color

I'm currently working on an electrolytic setting where a stainless steel (430 series, mainly made of iron and chromium, but no nickel) anode is dissolved in acidic environment (sulfuric and phosphoric ...
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2answers
187 views

Is there a potentiometric method for monitoring salt formation in organic solvent?

I work in a pharmaceutical R+D lab, and currently aim to develop a validatable potentiometric method for determining the optimal amount of acid to add to a basified small organic molecule for ...
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1answer
7k views

Standard reduction potential of MnO4-/MnO2 couple

This is the data given: $$\ce{MnO4- /Mn^{2+}} = 1.5~\mathrm{V}$$ $$\ce{MnO2 /Mn^{2+}}= 1.23~\mathrm{V}$$ I know that : $$\ce{MnO4- +5e- + 8H+ ->Mn^{2+}}$$ $$\ce{MnO2 + 4H+ +2e- -> Mn^{2+}}$$ ...
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2answers
90 views

In a half cell reaction, Is the potential halfed?

If you have an electrolyte of $\ce{Zn^2+}$ and $\ce{SO4^2-}$ (Neutral) Then you dip in it a Zinc electrode. Zinc potential is $\pu{-0.74 V}$ (relative to SHE). So that means there is a $\pu{-0.74V}$ ...
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0answers
37 views

What happens when you run house electricity through salt water?

What happens when you run house electricity (120VAC) through salt water? (with standard copper wires!) Well, in https://youtu.be/dcrY59nGxBg , an interesting experiment was conducted to find out! At ...
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1answer
162 views

Why is the peak-to-peak separation of cyclic voltammetry is 57 mV?

I'm studying CV, and I wonder if I can calculate the peak-to-peak separation of CV for a reversible redox system. I found that the separation is 57 mV on my textbook, and my teacher taught me that is ...
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1answer
881 views

How exactly does a battery work (specifically Pb/H2SO4/H2SO4/PbO2 lead acid battery)?

Specifically talking about the lead-acid battery, I understand (or think I understand) this much: The anode, in the presence of the electrolyte, $\ce{H2SO4}$ will be oxidised: $$\ce{Pb (s) + SO4^2- (...
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2answers
89 views

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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2answers
34 views

Is it possible to calculate the 'overall' redox potential of a system?

For a solution where many redox reactions occur (e.g. cytosol, soil solution), can we consider anything as 'overall' redox potential of a system? Is there a formula to quantify it in relation to the ...
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1answer
145 views

Does Intercalation and Deintercalation of Lithium ions occurs in Half Cell?

The important feature of Lithium ion batteries is the ability to intercalate and deintercalate lithium ions in anode and cathode . However when we use half cell, using lithium metal foil as anode, ...
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1answer
249 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 ...
2
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1answer
308 views

Kohlrausch Law and conductivity

Im writing up a lab report at the minute and part of it concerns ions in solution and how they affect conductivity. I've been doing lots of reading and I think ive got the grasp of most of it, but its ...
4
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1answer
2k views

Copper layer doesn't stick after Copper electroplating

I am playing around with copper plating using Copper Sulfate solution with electricity. I am using 2-2.5 volts as power source and around 100-500 mA. It is actually a very small container around 100 ...