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).

Filter by
Sorted by
Tagged with
1
vote
1answer
50 views

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 ...
0
votes
1answer
1k views

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 ...
10
votes
2answers
3k views

How does copper reduce dilute nitric acid to nitric oxide and concentrated nitric acid to nitrogen dioxide?

Here are the 2 equations: \begin{align} \ce{3Cu + 2NO3- + 8H+ &<=> 3Cu^2+ + 2NO + 4H2O} & E &= 0.62~\mathrm{V}\\ \ce{3Cu + 2NO3- + 4H+ &<=> 3Cu^2+ + 2NO2 + 2H2O}& E &...
5
votes
1answer
1k views

In a galvanic cell where the two electrodes are in the same electrolyte solution, why do reduction and oxidation occur separately?

In a certain book, I was presented with the following solution: An iron nail is attached by a piece of wire to a magnesium ribbon, and the iron and magnesium are placed into the same container, with ...
0
votes
0answers
172 views

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 ...
1
vote
1answer
10k views

Electrolysis of diluted sulfuric acid

My teacher told me that electrolysis of dil. $\ce{H2SO4}$ (concentration below $50\%$) using inert electrodes results in gradual increase of the concentration of $\ce{H2SO4}$. I can't seem to figure ...
2
votes
0answers
31 views

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 ...
-1
votes
1answer
67 views

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 ...
1
vote
0answers
23 views

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....
0
votes
1answer
119 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 ...
0
votes
1answer
57 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 ...
0
votes
1answer
43 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 ...
2
votes
3answers
263 views

Where to buy/How to build a Devanathan-Stachurski cell?

I'm preparing to do some hydrogen permeation tests to calculate the diffusivity of some iron samples. I would like to do this using the Devanathan-Stachurski cell, which consists of two cells, one ...
0
votes
1answer
562 views

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 ...
3
votes
2answers
5k views

What causes electrons to move from zinc to copper?

Here is something that no video in youtube about electrochemistry can explain me about galvanic cells. Suppose we have $\ce{Zn}$ metal immerse in $\ce{Zn^{2+}}$ in one side, then $\ce{Cu}$ metal ...
13
votes
1answer
11k 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 ...
2
votes
1answer
1k views

Positive electrode of an electrochemical cell?

I had the following problem: Relevant information from Data Book: $\ce{Ag+ + e- <=> Ag}$ $E^0 = +0.80$ and $\ce{Fe^3+ + e^- <=> Fe^2+}$ $E^0 = +0.77$ This means $...
3
votes
1answer
256 views

Electroplating diamond grit

I want to do electroplating with diamond grit and make profiling, grinding and cutting disks. (see the attached photos) I want to know the process to make the machine or the company whom is selling ...
1
vote
0answers
45 views

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{...
0
votes
1answer
937 views

How to calculate Debye length of a 2-1 electrolyte

I am given the Debye length to be 10nm for 0.001M KCl at 298K. I want to know its Debye length in 0.01M CaCl2. How can this be calculated? I know that for 1-1, the Debye length is inveresely ...
-1
votes
1answer
35 views

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 ...
0
votes
1answer
57 views

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 ...
1
vote
1answer
443 views

Water electrolysis - what is happening to an iron anode?

So I made an experiment to find a good electrolyte for a water electrolysis. I tried citric acid, which turned out to not produce any gases at the anode, I tried sodium hydroxide, which turned out to ...
1
vote
0answers
227 views

Reduced Graphene Oxide (RGO) Conductivity vs Everything Else

Reduced Graphene Oxide (RGO), is the reduced version of Graphene Oxide (GO). Both RGO & GO are easily manufactured when compared to the complex process used to manufacture the 'atom-thick' ...
-1
votes
1answer
39 views

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 ...
4
votes
2answers
3k views

Could a lead-acid battery electrolyte be replaced by hydrochloric or nitric acid?

Hydrochloric acid, as well as nitric acid, are also strong acids like sulfuric acid. So, why are not they used commercially in lead-acid batteries?
6
votes
3answers
18k views

Why would hydrogen not be generated at the cathode when electrolysing zinc sulfate?

Describe how zinc metal can be obtained from zinc sulfate solution by electrolysis. A labelled diagram is acceptable. Include all the products of this electrolysis. The electrolysis is similar to ...
14
votes
1answer
5k views

Why does Mg react vigorously in NaCl solution and less so in water?

When you put $\ce{Mg}$ into water a few $\ce{H2}$ bubbles appear. But when you put $\ce{Mg}$ into a $\ce{NaCl}$ solution there is a vigorous release of $\ce{H2}$, why is this and what reactions are ...
-2
votes
1answer
30 views

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?
2
votes
1answer
622 views

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 $\...
1
vote
1answer
106 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 ...
1
vote
1answer
950 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 ...
-1
votes
1answer
27 views

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 ...
24
votes
1answer
4k views

How can there be decimal subscripts in a molecular formula?

While learning about how batteries work I have encountered the following notation for a Li-ion cathode: $\ce{Li_{0.5}FePO4}$.[1] According to Wikipedia, the subscript number in a reaction equation ...
0
votes
2answers
204 views

Acrylic container and electrolysis

Normally when you do electrolysis, you would use a glass container. Would it be wise to use a acrylic container? I have one spare but not sure if this would affect the electrolysis process. Is there ...
5
votes
2answers
7k views

Ratios of produced gases in water electrolysis

I just did a little water electrolysis experiment at home by immerging two aluminum electrodes in water with a small amount of table salt. The voltage of the battery was 6 V. What surprised me is ...
0
votes
1answer
2k views

Bubble formation when aluminium reacts with copper(II) sulfate solution

I recently did an experiment putting pieces of $\ce{Al}$ and $\ce{Fe}$ into copper(II) sulfate solution and I noticed when the piece of aluminium was reacting, tiny bubbles were coming out whereas ...
-1
votes
1answer
397 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 ...
-1
votes
1answer
121 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 ...
3
votes
1answer
3k views

Tin in silver nitrate, any soln color change?

I have lab question in which a $\ce{AgNO3}$ solution with a tin strip placed in it is mentioned. This isn't a reaction we actually did in the lab, but due to a color change in the solution of one we ...
2
votes
0answers
87 views

Effect of passing hydrogen sulfide gas on electrode potential

Consider the cell reaction $$\ce{2Ag+ + Pb <=> 2Ag + Pb^2+}$$ If $\ce{H2S}$ gas is passed through the solution, what will be the effect on the EMF of the cell? My attempt: The Nernst ...
1
vote
2answers
324 views

Do the dimensions of the cathode and anode matter in electrochemistry?

I'm curious whether the dimensions of the cathode and anode matter in an electrochemical process. Let's take copper electrorefining as an example. For instance, should the cathode and anode be of the ...
1
vote
0answers
19 views

Detection limit of selective ion electrodes

I've been studying about the selective ion electrodes and I came across a question which I seem to not be able to answer. It has to do with why the detection limit for iodide ions is lower than the ...
3
votes
2answers
28k views

Half cells: difference between E(cell) = E(cathode}-E(anode) & E(cell) = E(oxidation) + E(reduction)

When do I use each of the above? If I use one or the other they give me difference results. For example, I'm trying to put the Volts into an equation to find standard free energy change. $$\Delta ...
0
votes
0answers
642 views

Why do the Metal Ions in an Electrochemical Cell Not Pass Through a Salt Bridge?

I understand that the purpose of a salt bridge is to maintain the neutrality of the solutions in an electrochemical cell, but why do the ions being oxidized and reduced not pass through the salt ...
0
votes
1answer
271 views

Signs of electrode potentials

Why is the oxidation potential given a positive sign and the reduction potential a negative one? Also, in my book a bunch of formulas are given without any explanation: $E^{o}_{cell}= $ Oxidation ...
3
votes
1answer
3k views

Significance of sign of standard reduction potential

I am very confused with the signs of standard reduction potentials. For example the standard reduction potential of Zinc is −0.76 V and that of copper is +0.34 V. I cannot understand the ...
5
votes
1answer
166 views

Galvanic cells/redox - confused regarding diagram

I'm not sure if I got this wrong because I interpreted the cell incorrectly. When they have an arrow pointing in to the tube for $\ce{O2}$, does this imply that $\ce{O2}$ is a reactant? If so then B ...
8
votes
1answer
7k views

Identity of a green substance formed during electrolysis reaction?

I did a short experiment in which I connected a $1.5\:\mathrm{V}$ battery with 2 paper clips into a bowl of water to which I added salt. After a while, I saw a yellowish-greenish cloud inside the ...
44
votes
3answers
288k views

Why is it important to use a salt bridge in a voltaic cell? Can a wire be used?

I was learning about voltaic cells and came across salt bridges. If the purpose of the salt bridge is only to move electrons from an electrolyte solution to the other, then why can I not use a wire? ...