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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1answer
42 views

Setup for Sensing change in concentration of NaCl

I am making a sensor to sense the change in concentration of NaCl. My background is in electronics and chemistry is not my strong area. I got some screen printed electrodes, with Silver (Working ...
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33 views

Predicting directions of redox reactions [closed]

Hello! In this textbook example question, how come the chlorine reaction, which has the greatest reducing power will not react? If it has the greatest E of 1.36 V that means it has most reducing ...
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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
55 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
47 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
31 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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41 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
52 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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144 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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44 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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38 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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1answer
29 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
26 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
921 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
223 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
51 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 ...
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1answer
52 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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26 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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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
76 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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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
27 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
121 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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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 ...
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2answers
30 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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1answer
9k 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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50 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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2answers
92 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
45 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
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 ...
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21 views

Greater ligand stabilization of the lower oxidation state increasing redox potential

According to Atkins, P.W., De Paula, J. and Keeler, J., 2006, Atkins' Physical Chemistry, $$ \begin{align} \ce{[Fe(CN)6]^3- + e- &<=> [Fe(CN)6]^4-} &\quad E^\circ &= \pu{+0.36 V} \...
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1answer
42 views

Keeping Li-Ion battery on charger vs. plug the charger in and out regularly

I have read on numerous occasions a set of recommendations to keep a Li-Ion battery happy: avoid discharging the device at all costs, don't charge it up completely, keep it as much as possible between ...
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1answer
12k views

If electrolysis splits water, why does only either hydrogen or oxygen (but not both) bubble up on one pole?

If electrolysis splits water, then that means that $\ce{H2O}$ is split into $\ce{H}$ and $\ce{OH}$ or $\ce{O}$. How come that if a water molecule is split at e.g. the negative pole (anode), only the ...
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7k views

Electrolysis of concentrated sulphuric acid

In my textbook it is given that for electrolysis of dilute sulfuric acid at anode following reactions can occur: At moderate concentrations $\ce{2H2O -> O2 + H+ +4 e-}$ And for high ...
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2answers
5k views

Why do positive ions go to the cathode?

In electrolysis why do positive ions go to the cathode? Since the cathode is positive, won't the positive ions face repulsion at the cathode and would require more energy? I understand that reduction ...
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1answer
75 views

Why does the rusting process start from the bent/squeezed portion of iron?

I have noticed that the rusting of iron starts from the squeezed or bent parts of iron piece. I want to know what is the peculiar reason for the observation that rusting starts from bent or irregular ...
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5k views

What is the role of hydrochloric acid in a copper electroplating bath?

Considering water as a given, the third most important ingredient in a copper electroplating solution, as a short survey of related recipe webpages will show you, is hydrochloric acid (HCl). Here's a ...
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How to calculate the energy required for an electrochemical reaction with over potential?

I am particularly interested in the reaction described in High‐Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N‐Doped Graphene Electrode. The reaction is $$ \ce{...
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3answers
5k views

Is it dangerous to inhale the steam coming from electrolysis of salt-water solution [closed]

Is chlorine in there that accumulates (at the anode) and emerge out as chlorine gas? I was worried since I added a pinch of salt to the steamer in order to hasten the heating of tap water when I ...
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1answer
5k views

How to identify the anode and cathode in a concentration cell?

How do I understand which is the anode and which is the cathode in this problem? We have a concentration cell with hydrogen electrodes. It's made up of two half-cells. One half cell contains [BaCl(...
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2answers
136 views

Does the salt bridge in a galvanic cell deplete over time?

I searched for the answer for this question on Wikipedia and Stackexchange a lot but couldn't find same question or a required answer in some other similar question. I understand that the function ...
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1answer
52 views

how can I measure the pH of a HF:H2O:CH3OH solution? [closed]

how can I measure the pH of a HF:H2O:CH3OH solution? more specifically, how can I precisely and accurately measure the H+ ion concentration?
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1answer
5k views

Does the concentration affect the voltage in electrochemistry?

For my electrochemistry lab I'm using $\pu{10 mL}$ of $\ce{ZnSO4}$ and $\pu{10 mL}$ of $\ce{CuSO4}$ solutions connected with a salt bridge. I connect $\ce{Zn}$ metal and $\ce{Cu}$ metal to a voltmeter ...
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1answer
59 views

Calculate voltage, cost and time of nickel coating

To nickel with a bath of $\ce{NiSO4}$ a cathodic current of $\pu{0.3 A/cm2}$ is applied with a square plate of side $\pu{5 cm}$ is used to nickel a certain substrate. Due to the formation of $\ce{H2}$ ...
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35 views

Copper plating with switched anode and cathode [closed]

Please help! I was working on a mock research project/lab for my chemistry class testing the rate of electroplating of copper vs. voltage. I had copper and nickel electrodes and .1M copper sulfate ...
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2answers
325 views

Does reduction/ oxidation take place separately at a half cell electrode?

In the redox reaction chapter, we learn that oxidation and reduction go hand in hand. The oxidising agent oxidises by accepting the electron released by the reducing agent and gets reduced in the ...
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3answers
6k views

How to calculate the solubility product for PbS from galvanic potential?

Knowing that at 25 °C the following galvanic cell: $$\ce{Pb~|~Pb(NO_3)_2~1M~||~PbS~saturated~|~Pb}$$ shows an $\mathrm{EMF} =0.413~\mathrm{V}$, find the $K_\mathrm{sp}$ of $\ce{PbS}$. My Approach ...
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1answer
43 views

Why is the cathode of a lithium-ion battery metallic, which is the opposite of most other batteries? [closed]

In most types of batteries, primary and secondary, the metallic electrode is the anode, and a non-metal acts as cathode. Or a pure metal is the anode, and the cathode is a metal oxide. Why is the ...
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28 views

The physical intuition behind some simplifications in electrochemistry

Find the standard reduction potential of $$\ce{AgIO3(s) + e- <=> Ag(s) + IO3-}.$$ $K_\mathrm{sp} = \pu{3.1E-8},$ and the standard reduction potential of $\ce{Ag +e- <=> Ag(s)}$ ...
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8k views

Why does increasing number of salt bridges increase voltage of electrochemical battery?

In an experiment, I set up a cell with lead nitrate (w/ lead electrode) and zinc sulfate (w/ zinc electrode), with a salt bridge containing potassium nitrate. I observed that by increasing the number ...

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