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>"Since change in enthalpy ∆H = Q + VΔP, it seems that enthalpy and heat flow (Q) are not strictly the same thing."
First, note that, when you write "∆H = Q + VΔP," you are assuming the only type of work is PV-work. That's a reasonable assumption for these discussions. It's just important to make that assumption e... |
>"Since change in enthalpy ∆H = Q + VΔP, it seems that enthalpy and heat flow (Q) are not strictly the same thing."
First, note that, when you write "∆H = Q + VΔP," you are assuming the only type of work is PV-work. That's a reasonable assumption for these discussions. It's just important to make that assumption e... |
>"Since change in enthalpy ∆H = Q + VΔP, it seems that enthalpy and heat flow (Q) are not strictly the same thing."
First, note that, when you write "∆H = Q + VΔP," you are assuming the only type of work is PV-work. That's a reasonable assumption for these discussions. It's just important to make that assumption e... |
I am looking for idea's on how to purify phosphoric acid for lab use, as the the price for reagent grade V's home-use ended with me buying a product designed as a rust-killer for steel... The percentage is actually quite high in this product (being 40%), but the unlisted agents added are obviously not going to result i... |
How do you purify phosphoric acid from cheap commercial (hardware-store) products? |
Would the mixture of Latex Rubber and the Squid's chitin make a biodegradable plastic? |
This is a follow-up question to [Why are isotopes an issue in reading mass spectra?][1]
A follow-up question: electrospray ionization (ESI) produces multiply charged species and charge can be >40 (for the purposes of m/z ratio), and assuming the difference in mass for an isotope is ~1 Da (with each additional neutro... |
What is the difference in Da of ESI analytes with multiple charges? |
> would the difference in weight for two isotopes each with a charge +10 be 0.1 Da?
Short answer: **yes**
Long answer: You said
> assuming there is only one additional isotope
This is a weird assumption, as it is often not true. Molecules containing both $\ce{H}$ atoms and $\ce{C}$ atoms will have isotopi... |
What is meaning of LAV2P basis set? |
I am trying to understand the following equations from a paper by Wang et al. \[[1](https://doi.org/10/gdj4h5), [p. 5 at the SI\]][1]:
> ### Michaelis–Menten Representation of the Kinesin Cycle
> We assumed that there is a strong coupling between ATP turnover rate of kinesin and kinesin stepping on an MT. Each c... |
My questions are as follows:
For the Daniell cell, we assume that ZnSO4 and CuSO4 are 1M aqueous solutions. What if we use pure molten ZnSO4 and CuSO4 instead?
Assume that we prepare an isolated half-cell containing just a zinc metal bar immersed in a ZnSO4 solution, without any connection to any other half-cells... |
There is video footage of nearby villages in Pripyat, in the first week after the Chernobyl disaster. When I watch it there are villagers leading normal lives in normal clothing. Some Russian nuclear scientists pass by in full radioactive suits. Then there these clearly visible "flashes" in the air; I have looked on yo... |
What caused the flashes in the video footage of Chernobyl? |
There is video footage of nearby villages in Pripyat, in the first week after the Chernobyl disaster. When I watch it there are villagers leading normal lives in normal clothing. Some Russian nuclear scientists pass by in full radioactive suits. Then there these clearly visible "flashes" in the air; I have looked on yo... |
There is video footage of nearby villages in Pripyat, in the first week after the Chernobyl disaster. When I watch it there are villagers leading normal lives in normal clothing. Some Russian nuclear scientists pass by in full radioactive suits. Then there these clearly visible "flashes" in the air; I have looked on yo... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/oZ9J9.png
hi,
why is there no formation of epoxide when the two (oH) are on different planes?
I do understand the epoxidation mechanism. However, I would be grateful if someone cleared the specific requirements for epoxidation. |
I have always been a bit confused about column pressure limits. I have to elaborate a bit on the problem to get to my question:
In protein purification we use the äkta purification machines (e.g. äkta explorer), which always come with a high pressure and low pressure alarm setting for the column in their unicorn so... |
[![1,2-diol + SOCl2][1]][1]
Why is there no formation of epoxide when the two OH-groups are on different planes? I do understand the epoxidation mechanism. However, I would be grateful if someone cleared the specific requirements for epoxidation.
[1]: https://i.stack.imgur.com/CMRvw.png |
> **TL;DR** The $\mathrm{d}_{z^2}$ orbital is a result of solving the Schrödinger equation for the hydrogen atom in the most mathematically convenient way.
To properly understand this, it is necessary to go back to the fundamentals. The *complex* d-orbitals are obtained by solution of the Schrödinger equation. In ge... |
There is video footage of nearby villages in Pripyat, in the first week after the Chernobyl disaster. When I watch it there are villagers leading normal lives in normal clothing. Some Russian nuclear scientists pass by in full radioactive suits. Then there these clearly visible "flashes" in the air; I have looked on yo... |
Understanding the Kolmogorov backward equations in active biological systems? |
[![enter image description here][1]][1]
When acetic acid looses hydrogen acetate, ion is formed which attacks 4-chlorobutene forming methyl butenoate. How does cyclic structure form?
does the lone pair of oxygen attacks butene internally?
[1]: https://i.stack.imgur.com/ODCWt.jpg |
There is video footage of nearby villages in Pripyat, in the first week after the Chernobyl disaster. When I watch it there are villagers leading normal lives in normal clothing. Some Russian nuclear scientists pass by in full radioactive suits. Then there these clearly visible "flashes" in the air; I have looked on yo... |
> Which of the following has the highest molar conductivity?
> (**A**) Diaminedichloroplatinum(I)
> (**B**) Tetraamminedichlorocobalt(III) chloride
> (**C**) Potassium hexacyanoferrate(II)
> (**D**) Hexaaquochromium(II) bromide
Since mobility depends on the size, charge and the number of particles, how c... |
Is sodium acrylate soluble in ethanol? |
Electron can move from one location to another if it feels a force that is if there is a presence of electric field.Now suppose I have a Zn rod immersed in CuSO4 solution.Electrons are transferred from Zn to Cu.What results in this motion of electrons from Zn to Cu.How can electron move without a field ? |
What causes the movements of electron between two metals? |
The Amazon website gives the composition of Peressigsaure/Alkohol: Inhaltsstoffe pro 100g:
● 19g 2-Propanol
● 5g Ethanol
● <1% Wasserstoffperoxid
● <1% Peroxyessigsäure
● <1% Essigsäure
Working time 30 seconds, shelf life 12 months.
Don't exp... |
Electron can move from one location to another if it feels a force that is if there is a presence of electric field. Now suppose I have a $\ce{Zn}$ rod immersed in $\ce{CuSO4}$ solution. Electrons are transferred from $\ce{Zn}$ to $\ce{Cu}$. What results in this motion of electrons from $\ce{Zn}$ to $\ce{Cu}$. How can ... |
For a specific experiment, I'm looking for a dye which would emit around 680nm. Preferably one I could buy easily commercially. Are there any databases which might give the emission spectra of specific dyes? Or any other methods to find dyes at around 680nm.
|
For a specific experiment, I'm looking for a dye which would emit around 680nm. Preferably one I could buy easily commercially. Are there any databases which might give the emission spectra of specific dyes? Or any other methods to find dyes at around 680nm.
|
Are there any gasses that can not be turned into liquid, or liquids that can not be frozen solid? |
For a specific experiment, I'm looking for a dye which would emit around $\pu{680nm}$. Preferably one I could buy easily commercially. Are there any databases which might give the emission spectra of specific dyes? Or any other methods to find dyes at around $\pu{680nm}$.
|
$$\Delta H = \left( \begin{array}{c} \text{total enthalpy of}\\ \text{bonds broken}\end{array}\right)-\left( \begin{array}{c} \text{total enthalpy of}\\ \text{bonds made}\end{array}\right)$$
$$\Delta H = \sum \Delta H_\mathrm{F} \left( \text{products}\right)-\Delta H_\mathrm{F} \left( \text{reactants}\right)$$
... |
$$\Delta H = \left( \begin{array}{c} \text{total enthalpy of}\\ \text{bonds broken}\end{array}\right)-\left( \begin{array}{c} \text{total enthalpy of}\\ \text{bonds made}\end{array}\right)$$
$$\Delta H = \sum \Delta H_\mathrm{F} \left( \text{products}\right)-\Delta H_\mathrm{F} \left( \text{reactants}\right)$$
... |
I know Aqua regia is used for purifying gold by dissolving gold in it, but how that dissolved gold is obtained back in the pure state?
I searched everywhere, but I didn't get the answer. So, I am asking here. |
How pure gold is obtained back from dissolved state in Aqua regia? |
From what I've seen in alkanes, their complete combustion creates carbon dioxide, which has carbon in its highest possible oxidation state. I've been wondering what complete combustion would look like in similar compounds, such as ammonia, phosphine, hydrogen sulfide, and silane.
After looking at through several se... |
I read calcium carbonate is the main component of seashells and other animals' shells (such as snails), and also limestone. How can I prepare pure $\ce{CaCO_3}$?
Could someone describe the process and the chemical equations involved? I saw [this video][1] and apparently that's one way. Are there others? For example,... |
How to obtain calcium carbonate? |
For a specific experiment, I'm looking for a dye which would emit around 680 nm. Preferably one I could buy easily commercially. Are there any databases which might give the emission spectra of specific dyes? Or any other methods to find dyes at around 680 nm.
|
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/kMCJg.png
In the above oxidation reaction, does the 2 protons and electrons released get accepted by oxygen molecules? If not, where do they go?
Appreciate all answers :) |
Where does the protons and electrons go in this redox reaction? |
You say:
> I searched everywhere, but I didn't get the answer.
When I type `youtube gold recovery from chloroauric acid` into [Google](https://lmgtfy.com/?q=youtube+gold+recovery+from+chloroauric+acid), the first link is to a Youtube video with a visible demonstration of converting chloroauric acid to gold.
T... |
Are there any gases that can not be turned into liquid, or liquids that can not be frozen solid? |
Is there any book where specific heat capacities are given? |
I saw this passage on a book and it says that LMCT overpowers d-d transitions thus the permanganate ion has an intense purple color. However, it was mentioned that the Mn+7 ion was momentarily reduced to Mn+6 in the charge transfer, how is that?
[![enter image description here][1]][1]
[1]: https://i.stack.img... |
How is Mn+7 in the Permanganate ion considered as momentarily reduced to +6 in LMCT? |
> What is the effect of air pressure on the melting point of a substance?
> **a**) No effect
> **b**) The melting point increases when the air pressure increases
> **c**) The melting point decreases when the air pressure increases
The boiling point has inverse relation with vapor pressure of the liquid and ... |
I saw this passage on a book and it says that Ligand to Metal Charge Transfer (LMCT) overpowers d-d transitions thus the permanganate ion has an intense purple color. However, it was mentioned that the Mn+7 ion was momentarily reduced to Mn+6 in the charge transfer, how is that?
[![enter image description here][1]][... |
From what I've seen in alkanes, their complete combustion creates carbon dioxide, which has carbon in its highest possible oxidation state. I've been wondering what complete combustion would look like in similar compounds, such as ammonia, phosphine, hydrogen sulfide, and silane.
After looking at through several se... |
You say:
> I searched everywhere, but I didn't get the answer.
When I type `youtube gold recovery from chloroauric acid` into [Google](https://lmgtfy.com/?q=youtube+gold+recovery+from+chloroauric+acid), the first link is to a Youtube video with a visible demonstration of converting chloroauric acid to gold.
T... |
What causes oxygen cylinders to explode when in contact with oil (oiled cloth)? |
Strictly on theoretical basis, not based on experimental results.
I can very well be wrong, but I think that methanol should be
optically inactive because it has a plane of symmetry passing through it.
My teacher however insists that it is optically active as you can create two non-superimposable mirror images ou... |
Is methanol optically active? |
Arrhenius equation using concentration? |
The wording of the question hides the answer.
Electrons do not move from Zn to Cu. They move from neutral zinc to cupric ion Cu++. The field arises from the mix of H2O, H+, OH-, SO4--, and Cu++ all around the Zn rod. Could electrons be forced onto Zn from OH- or SO4-- ? No.There is no gain in stability; energy would... |
How can electron move between two metals without the presence of electric field? |
I was probing for first order Jahn-Teller instability in the coordination complex CrCl4 (2 electrons in E set). Taking the direct product yields the states A1 + A2 + E, so I took the symmetric and antisymmetric direct products too to see which states represented a singlet and triplet configurations.
To my surprise,... |
Why is it important to know the spin of bioinorganic complexes? |
I have a limited background in chemistry (nothing beyond general Chem 2), so I am asking for help with a group project. We have two chemists on our team, but communication is limited at the time and I am trying to answer some specific questions for myself so that we can move forward. We're designing a probe to study th... |
How appropriate/adaptable is HPLC for in situ sample analysis on Titan? |
I weighted my Hydroiodic acid sample,
25ml weight 34.1g, so density is about 1.364.
I want to know its concentration based on density, anyone had corresponding density chart? |
Yes. Researchers have been using atomic force microscopy (AFM) and scanning tunneling microscopy (STM) for some time for this purpose. Do note that these images are not photographs in the sense that we usually think of "pictures" and are indirect measurements of constituents of the molecule. However, they do yield "pic... |
What chemical can be used for getting rid of hard water spots on cars? |
100 mL of a 0.1 mM buffer solution made from acetic acid and sodium acetate with pH 5.0 is diluted to 1 L. What is the pH of the diluted solution?
The pKa value for acetic acid is given as 4.75.
The answer provided in my textbook is pH = 5.53. The closest that I can get to that is pH = 5.507. I know that's an alm... |
> How can electron move without a field?
There is a field, the field of two nuclei (shielded by some electrons, if you will). In the figure below, the top shows the potential energy (y-axis, arbitrary units) of a free electron in a homogeneous electric field (changing along the x-axis). It will move along the gradie... |
I'm asking because this makes no sense to me and making sure I'm not stupid.
I brewed 10 gallons of cold brew concentrate(TDS 12.2) and mixed it with 10 gallons of water.
I moved 10 gallons of the mixture into kegs and they ended up at TDS 6.4. Two hours later I filled the rest of the kegs. One keg was at TDS 4.8... |
coffee concentrate and water separated after 2 hours. How/why? |
I have Pyrope crystal structure, downloaded from materialsproject:
https://materialsproject.org/materials/mp-6073/#
It appeared as triclinic cell, but if you download CIF file and open it from softwares like Avogadro or VESTA, it appeared as a orthogonal simple cubic (a=b=c, alpha = beta = gamma = 90 degree). I al... |
How can I find the smaller symmetric structure from big crystal unit cell? |
I have Pyrope (Mg3Al2(SiO4)3) crystal structure, downloaded from materialsproject:
https://materialsproject.org/materials/mp-6073/#
It appeared as triclinic cell, but if you download CIF file and open it from softwares like Avogadro or VESTA, it appeared as a orthogonal simple cubic (a=b=c, alpha = beta = gamma = ... |
Will using vinegar harm car paint? |
That is a valid question, because [acid rain has been known to damage paints][1], particularly high-gloss, i.e. clear coat. Best would be to test the effect of vinegar on a hidden area, and double-check under *bright* light from different angles. Your idea to test on glass is good, because it shows how long a soak is n... |
It is a very good question because this is an active area of research. Having heard talks from the actual people who are making analytical instruments for space analysis, I can mention the actual issues before coming to your actual question so that you are aware of the latest problems. As far as I know, HPLCs have not ... |
Can you use the torque of a photon to change bond angles, ect? 11-Cis-Retinal to the all trans version, in the eye, is a good illustration.
https://science.sciencemag.org/content/364/6447/eaaw9486
Note: This phenomenon can be observed by closing blinds, allowing the sun to shine through, you get light beams. If ... |
Can you use a Photons torque to change a molecule? |
I weighted my hydroiodic acid sample: 25 ml weight 34.1 g, so the density is about 1.364 g/ml.
I want to know its concentration based on density. Does anyone have the corresponding density chart? |
Can you use the torque of a photon to change bond angles, etc.? 11-Cis-Retinal to the all trans version, in the eye, is a good illustration \[[1](https://doi.org/10/gf4f6h)\].
Note: This phenomenon can be observed by closing blinds, allowing the sun to shine through, you get light beams. If you blow a smoky materia... |
Can you use a photon's torque to change a molecule? |
During titration of KMno4 with oxalic acid , can we use conc.H2SO4 or HNO3 instead of bench sulfuric acid? |
Let's take the conjugated alkyne chain (e) below, taken from [Wikipedia](https://en.wikipedia.org/wiki/Alkyne):
> [![enter image description here][1]][1]
How would one typically go about synthesising such a conjugated chain with a series of alkyne functions?
[1]: https://i.stack.imgur.com/EU4ab.png |
How can one synthesise a conjugated alkyne chain? |
I plan to do an experiment which involves the electrolysis of dilute sulfuric acid ( 1M or 1 mol/l ). I would like to carry it out in a long transparent plastic container ( easier to handle and clean ). What would be the suitable plastic for this? |
During titration of $\ce{KMnO4}$ with oxalic acid, can we use conc. $\ce{H2SO4}$ or $\ce{HNO3}$ instead of bench sulfuric acid? |
How to explain Gibbs free energy is a pressure-dependent state function? |
I'm aware that through deriving Gibbs free energy to infinitesimal changes, we could get the formula:
dG = Vdp - SdT, giving that Gibbs free energy is pressure-dependent.
However, while dealing with the definition of Gibbs free energy: ΔG = ΔH − TΔS, (and ΔH must be held at constant temperature, am I wrong?) most t... |
How do we find the oxidation state of individual carbon in Mg₃C₂. Explain with the help of structure if possible. For the average oxidation number, we can exploit the fact that the molecule will be electrically neutral, but what about the individual atoms of carbon? |
I plan to do an experiment which involves the electrolysis of dilute sulfuric acid (1 M or 1 mol/L). I would like to carry it out in a long transparent plastic container (easier to handle and clean). What would be the suitable plastic for this? |
I'm aware that through deriving Gibbs free energy to infinitesimal changes, we could get the formula: $dG = Vdp - SdT$, giving that Gibbs free energy is pressure-dependent.
However, while dealing with the definition of Gibbs free energy: $ΔG = ΔH - TΔS$ (and $ΔH$ must be held at constant temperature, am I wrong?) mo... |
In AB5E type molecules, why are the lone pairs in axial bonds?
[![Shape of AB5E][1]][1]
[1]: https://i.stack.imgur.com/XGjOU.png
> If the lone pair is present in axial bonds it repels four other bonds.
> On the other hand if the lone pair is in equatorial bonds, it repels
> only two other bonds.
So what... |
During titration of $\ce{KMnO4}$ with $H_2C_2O_4$, can we use conc. $\ce{H2SO4}$ or $\ce{HNO3}$ instead of bench sulfuric acid? |
During titration of $\ce{KMnO4}$ with $H_2C_2O_4$, can we use concentrated $\ce{H2SO4}$ or $\ce{HNO3}$ instead of bench sulfuric acid? |
*Why?* Because there is no other choice. Starting from the AB6 octahedral configuration, all six vertices of the octahedron are symmetric, so it doesn't matter whichever one you “choose” to replace by the lone pair. All will yield the same final configuration. |
During titration of $\ce{KMnO4}$ with $\ce{H2C2O4}$, can we use concentrated $\ce{H2SO4}$ or $\ce{HNO3}$ instead of bench sulfuric acid? |
In $\ce{AB5E}$-type molecules, why are the lone pairs in axial bonds?
[![Shape of AB5E][1]][1]
[1]: https://i.stack.imgur.com/XGjOU.png
> If the lone pair is present in axial bonds it repels four other bonds. On the other hand if the lone pair is in equatorial bonds, it repels only two other bonds.
So w... |
I'm aware that through deriving Gibbs free energy to infinitesimal changes, we could get the formula: $\mathrm dG = V\,\mathrm dp - S\,\mathrm dT$, giving that Gibbs free energy is pressure-dependent.
However, while dealing with the definition of Gibbs free energy: $ΔG = ΔH - TΔS$ (and $ΔH$ must be held at constant ... |
What tests were conducted in the ancient days to determine whether a given substance was an element, say, how could one say that mercury, gold, silver, sulphur, phosphorous were elements? |
What were the tests to determine that a substance is an element or not? |
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