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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 $\pu{-0.74V}$ **difference** between the electrolyte and the electrode.
**But** When you dip in the solution the electrode makes... |
Why does Gibbs free energy correspond solely to non-expansion work? |
First of all: I know this question has been asked before (Why does the Gibbs free energy only correspond to non-expansion work?), and although I understand the mathematical derivation given there, I struggle with the concept.
If both $\Delta G$ is negative and the change in enthalpy is negative (exothermic), I don't... |
# Q1: The equilibrium concentration ***c*** of a gas in a solution (typically water) which is present in the atmosphere with partial pressure ***p*** dictated by Henry's Law:
$H_{cp} = c/p$
where $H_{cp}$ is Henry's coefficient for that specific gas.
This law states that the concentration of the gas in the sol... |
_If this question is better suited for the Earth Science StackExchange or another StackExchange please let me know._
Edit 1: Modified for clarity and brevity.
----------
Something that's unclear to me is the exact relationship between gases within an atmosphere and the concentration of those gases within a lar... |
I was taught that the the pre-exponential factor $A$ in the Arrhenius equation \eqref{arrhenius} does not increase with temperature.
$$k = A\cdot\mathrm \exp\left(-\frac{E_\mathrm a}{RT}\right)\tag1\label{arrhenius}$$
But, a component of the pre-exponential factor is the *number of collisions*, which presumably i... |
If you think about protonating 1-propyne on the terminal acetylenic carbon, you get a vinylic cation that could apparently form an allylic cation by a hydride shift. The bond to the hydride that would shift has to be lined up with the empty orbital to which it is migrating.
So far, no problem. But after the shift, t... |
Is the value of 'A' necessarily the same for two different reactions taking place at the same temperature?
It's actually a part of another question which is if the rate constant k1 of a reaction is found to be double that of rate constant k2 of another reaction the relationship between corresponding activation energie... |
In my text book, it is written that NH3 is a base. They mentioned the reason for this is that it produces OH- ions in water. They stated this reaction,
> NH3 + H2O --> NH4OH
So That's why, they said that it is a base.
But in a neutralization reaction, mentioned by our teacher,
Acid + Base = Salt + water
... |
In my text book, it is written that $\ce{NH3}$ is a base. They mentioned the reason for this is that it produces $\ce{OH-}$ ions in water. They stated this reaction:
> $\ce{NH3 + H2O -> NH4OH}$
So That's why, they said that it is a base.
But in a neutralization reaction, mentioned by our teacher,
Acid + Ba... |
Open cardboard boxes/crates, often for foodstuffs, are often glued to hold their shape. What is the glue made of?
I ask to know if it is biodegradable, such that it is suitable for composting/gardening.
My preliminary research seems to indicate polyvinyl acetate (PVA), which seems to biodegrade fast enough for my... |
While studying about the characteristics of **Chemical Equilibrium**, I came across a point in my book which read
>**_A chemical equilibrium can be established only if none of the products is allowed to escape out or separate out as a solid (precipitate)_**
I understand that if one of the products is a gas and es... |
The statement is inaccurate. A better statement would be something like:
> A chemical equilibrium can not be established if one of the products is continuously removed (i.e. its concentration always decreases).
If one of the products is a gas and can mix with earth's entire atmosphere, that would make its concent... |
The statement is inaccurate. A better statement would be something like:
> A chemical equilibrium can not be established if one of the products is continuously removed (i.e. its concentration always decreases).
If one of the products is a gas and can mix with earth's entire atmosphere, that would make its concent... |
> Reversible reactions constitute a limiting case between spontaneous and non-spontaneous processes [?]
A **reversible process** is a hypothetical process where the entropy of the system and its surrounding is constant. This is hypothetical because nothing happens unless the entropy increase at least a tiny bit. In ... |
Boron is a non metal i. e. it accepts electrons and acids donate electrons so boron should react with acid but it doesn't. Why?? |
Boron is a non-metal, i.e. it accepts electrons and acids donate electrons, so boron should react with acid but it doesn't. Why? |
comfrey (*Symphytum officinale*) is a well known plant to organic growers. One of its features is that the leaves break down very quicky, either in water or in a container closed from UV light. There must be some chemical explanation for this, can you explain to me what that is ?
Thanks Erin |
Who said boron is a base? The fact that it does not weaken or neutralize most acids ought to tip you off that it isn't.
Boron is slowly oxidized when powdered and exposed to nitric acid (see [here](http://objetoseducacionais2.mec.gov.br/bitstream/handle/mec/10496/reactions/5.htm)), and we may call it "basic" by vir... |
I did my own research, and according to [The Engineering Toolbox](http://www.engineeringtoolbox.com/evaporation-water-surface-d_690.html),the formula for the evaporation rate of water is as follows:
$g_\mathrm h = \Theta A (x_\mathrm s - x)$
$g_\mathrm h$ = amount of evaporated water per hour ($\mathrm{kg/h}$)
... |
It is true that acetone is less polar than ethanol.
I thought the dipole moment is proportional to polarity, and if so, the dipole moment of acetone should be lower than ethanol.
But the dipole moment of acetone is higher than ethanol.
Why is it higher? |
Why is the dipole moment of acetone higher than ethanol? |
> What is the value of $x$ if $x$ molal solution of a compound in benzene has a mole fraction of solute equal to 0.2?
I tried calculating the moles of $x$ through the value given but there are two variables, i.e mole of $x$ and mole of benzene so I am stuck. |
What is the value of X if X molal solution of a compound in benzene has a mole fraction of solute equal to 0.2? |
Why can solid lubricants operate only at lower temperature in oxidizing environment but higher temperature in reducing environment? |
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 $\pu{-0.74V}$ **difference** between the electrolyte and the electrode.
**But** When you dip in the solution the electrode makes... |
Erin, the main the problem with the question is apparently this part "*One of its features is that the leaves break down very quickly, either in water or in a container closed from UV light*." You also mention the compound *comfrey* and wonder if this is responsible for a quick decomposition? I don't think so.
The k... |
comfrey (*Symphytum officinale*) is a well known plant to organic growers. One of its features is that the leaves break down very quickly, either in water or in a container closed from UV light. There must be some chemical explanation for this, can you explain to me what that is ?
Thanks Erin |
Why does Comfrey Break Down Easily? |
I would like to know how to make 1-phenylprop-1-ene(C6H5-CH=CH-CH3) from propiophenon(C6H5-CO-CH2-CH3)?
I think carbonyl group(C=O) of propiophenon is electron withdrawing group because of Oxygen of carbonyl group.
So the carbonyl group of propiophenon will be attacked by nucleophile. And this will be oxidized to m... |
I would like to know how to make 1-phenylprop-1-ene(C6H5-CH=CH-CH3) from propiophenon(C6H5-CO-CH2-CH3)?
I think carbonyl group(C=O) of propiophenone is electron-withdrawing group because of Oxygen of carbonyl group.
So the carbonyl group of propiophenone will be attacked by nucleophile. And this will be oxidized to... |
I would like to know how to make 1-phenylprop-1-ene(C6H5-CH=CH-CH3) from propiophenone (C6H5-CO-CH2-CH3)?
I think carbonyl group(C=O) of propiophenone is electron-withdrawing group because of Oxygen of carbonyl group.
So the carbonyl group of propiophenone will be attacked by nucleophile. And this will be oxidized ... |
# Q1: The equilibrium concentration ***c*** of a gas in a solution (typically water) which is present in the atmosphere with partial pressure ***p*** dictated by Henry's Law:
$H_{cp} = c/p$
where $H_{cp}$ is Henry's coefficient for that specific gas.
This law states that the concentration of the gas in the sol... |
I recently read in a book that rain is considered Acid Rain if the pH falls below 5.6. However a substance is acidic when the pH is below 7; so why is the boundary for Acid Rain 5.6?
I was thinking pH between 5.6-7 would be too dilute to have an effect on limestone and other materials that's why the pH has to be und... |
Amino acids can be broken down to yield pyruvate, which in turn can be used to construct glucose molecule in the process of gluconeogenesis. What happens to the Sulfur atom in the amino acid Cysteine when it is processed into pyruvate?
https://www.ncbi.nlm.nih.gov/books/NBK22453/figure/A3241/?report=objectonly
... |
Amino acids can be broken down to yield pyruvate, which in turn can be used to construct glucose molecule in the process of gluconeogenesis. What happens to the sulfur atom in the amino acid cysteine when it is processed into pyruvate?
[![enter image description here][1]][1]
<sup>Image source: [NCBI Bookshelf](h... |
What is the fate of sulfur in cysteine when it participates in gluconeogenesis? |
I have a need to use more pressure differential than can be afforded by vacuum vs atmospheric pressure alone, and so I've come to consider using pressurised laboratory glassware for part of my setup.
I've made a little bit of research here on stack-exchange and on google and the general information I've gathered i... |
Order of resistance to internal pressure to expect from laboratory glassware? |
I have a need to use more pressure differential than can be afforded by vacuum vs atmospheric pressure alone, and so I've come to consider using pressurised laboratory glassware for part of my setup.
I've made a little bit of research here on stack-exchange and on google and the general information I've gathered is ... |
Order internal pressure resistance to expect from laboratory glassware? |
While reading about equilibrium, I read that the equilibrium constant, K<sub>c</sub> changes with temperature due to the forward and backward reactions having different activation energies. Is is possible for a reaction to have the same activation energy for the forward and backward reactions, such that K<sub>c</sub> d... |
While reading about equilibrium, I read that the equilibrium constant, $K_\mathrm{c}$ changes with temperature due to the forward and backward reactions having different activation energies. Is it possible for a reaction to have the same activation energy for the forward and backward reactions, such that $K_\mathrm{c}$... |
While reading about equilibrium, I read that the equilibrium constant, $K_\mathrm{c}$, changes with temperature due to the forward and backward reactions having different activation energies. Is it possible for a reaction to have the same activation energy for the forward and backward reactions, such that $K_\mathrm{c}... |
I would like to know how to make 1-phenylprop-1-ene ($\ce{C6H5-CH=CH-CH3}$) from propiophenone ($\ce{C6H5-CO-CH2-CH3}$)?
I think carbonyl group ($\ce{C=O}$) of propiophenone is electron-withdrawing group because of Oxygen of carbonyl group.
So the carbonyl group of propiophenone will be attacked by nucleophile. And... |
Hello we are trying to prepare a solvent based solution of different kinds of minerals which can be added to reverse osmosis permeate water so that some of the essential minerals can be added back to the water. Do anyone knows which solvent we should use? |
I am aware of the fact that hybridization does not ALWAYS produce a stable structure (example: PH3)
However, my question is, what makes hybrid orbitals so effective in forming stable bonds? Although exceptions like PH3 do exist, what makes hybridization the best option for stability most of the time?
Is it due to th... |
Why does hybridization produce a more stable structure? |
I think water is the best solvent, assuming you want to remineralise the RO water for drinking it. Your solution might become a slurry depending on the required volume. Have you considered simply using a solid mix of these minerals? A solid mix would allow for a more homogeneous mix of different minerals than a low vol... |
Open cardboard boxes/crates, often for foodstuffs, are often glued to hold their shape. What is the glue/adhesive made of?
I ask to know if it is biodegradable, such that it is suitable for composting/gardening.
My preliminary research seems to indicate polyvinyl acetate (PVA), which seems to biodegrade fast enou... |
What are glues/adhesives for cardboard boxes/crates made of? |
Why is cyclopentadiene ($\mathrm{p}K_\mathrm{a} = 16$) less acidic than
A) 2,4-pentanedione $(\mathrm{p}K_\mathrm{a} = 9);$
B) phenol $(\mathrm{p}K_\mathrm{a} = 10);$
C) water $(\mathrm{p}K_\mathrm{a} = 15.7)?$
*Cyclopentadiene forms an aromatic compound as conjugate base and is quasiaromatic*, while phenol... |
My textbook states the following information:
> If a system were at absolute zero, an additional small amount of heat energy would lead to an infinite increase in entropy. Such a state is impossible. Absolute zero can never be achieved.
It also provides the equation:
$$ ∆S_{surroundings} = \frac{-∆H_{system}}{... |
I recently encountered a question while solving previous year question papers for JEE.
This is a question from JEE mains 2005 or as it was known as at that time AIEEE.
The question states that equimolar solutions in the same solvent have?
There are four options and the correct answer is same boiling and same freez... |
At low concentrations for which the ideal bp elevation/fp depression expressions usually apply, molarity is linearly proportional to molality, therefore the statements are equivalent.
[This webpage][1] explains nicely why low concentrations are important:
> Raoult's law only works for low concentration solutions... |
My textbook states the following:
> If a system were at absolute zero, an additional small amount of heat energy would lead to an infinite increase in entropy. Such a state is impossible. Absolute zero can never be achieved.
It also provides the equation:
$$ ∆S_{surroundings} = \frac{-∆H_{system}}{T}$$ Where T... |
I recently encountered a question while solving previous year question papers for JEE.
This is a question from JEE mains 2005 or as it was known as at that time, AIEEE.
The question states that equimolar solutions in the same solvent have?
There are four options and the correct answer is same boiling and sa... |
My textbook states the following:
> If a system were at absolute zero, an additional small amount of heat energy would lead to an infinite increase in entropy. Such a state is impossible. Absolute zero can never be achieved.
It also provides the equation:
$$ \Delta S_\text{surroundings} = \frac{-\Delta H_\text... |
The [wikipedia page for Ferrous oxide][1] states that FeO can be prepared by the thermal decomposition of iron(II) oxalate, with the following reaction:
FeC2O4 → FeO + CO2 + CO
And that the procedure is conducted under an inert atmosphere to avoid the formation of ferric oxide.
[This book][2] states that F... |
What is the most convenient way to prepare Ferrous oxide (FeO) in the laboratory? |
The [Wikipedia page for ferrous oxide][1] states that $\ce{FeO}$ can be prepared by the thermal decomposition of iron(II) oxalate, with the following reaction:
$\ce{FeC2O4 → FeO + CO2 + CO}$
And that the procedure is conducted under an inert atmosphere to avoid the formation of ferric oxide.
[This book][2] s... |
Quoting Wikipedia: ["Some enzymes operate with kinetics which are faster than diffusion rates, which would seem to be impossible."][1] Which are those enzymes and how can they be so fast?
One example is catalase in which peroxide is catalyzed faster than the diffusion rate of peroxide allows. Lionel Milgrom discusse... |
How can some enzymes work faster than the diffusion rates of the reactants allow? |
**Solution 1**
Let's assume there is 1 mole total of solvent and solute. With a mole fraction of 0.2 solute, there is 0.2 mole of solute, the rest (0.8 mole) is benzene. We can calculate the mass of 0.8 mole benzene from the molar mass, and express it in kilograms:
$$ m_\mathrm{benzene} = n_\mathrm{benzene} \cdot... |
$$\mathrm{molarity} = \frac{\text{amount of solute}}{\text{volume of solution}} $$ and amount of substance is based on quantity (larger mass means larger amount), so how come it is an intensive property. Shouldn't it be an extensive property?
|
Is molarity an intensive property? |
**Solution 1**
Let's assume there is 1 mole total of solvent and solute. With a mole fraction of 0.2 solute, there is 0.2 mole of solute, the rest (0.8 mole) is benzene. We can calculate the mass of 0.8 mole benzene from the molar mass, and express it in kilograms:
$$ m_\mathrm{benzene} = n_\mathrm{benzene} \cdot... |
How do I determine molality from mole fraction without knowing how much of the solution I have? |
The [Wikipedia page for ferrous oxide][1] states that $\ce{FeO}$ can be prepared by the thermal decomposition of iron(II) oxalate, with the following reaction:
$$\ce{FeC2O4 → FeO + CO2 + CO}$$
And that the procedure is conducted under an inert atmosphere to avoid the formation of ferric oxide.
Sicius' *Eisen... |
What is the most convenient way to prepare ferrous oxide (FeO) in the laboratory? |
If I have an igneous rock shown by geologic study to be 10,000 years old, approximately what percentage of the atoms (or protons, etc) in the rock might be the same ones that were in it 10,000 years ago? Is it reasonable to even think of a "particular", individual atom? Is it the "formation" of particles that persist... |
To answer your question, we can use the idea of radioactive decay;
According to the IB Physics Book from Oxford University, radioactive decay is "a naturally occurring process in which the nucleus of an unstable atom will spontaneously change into a different nuclear configuration by the emission of combinations of ... |
To answer your question, we can use the idea of radioactive decay;
According to the IB Physics Book from Oxford University, radioactive decay is "a naturally occurring process in which the nucleus of an unstable atom will spontaneously change into a different nuclear configuration by the emission of combinations of ... |
Is there a molecular orbital/Woodward-Hoffmann explanation as to why Diels-Alder reactants don't commonly undergo electrocyclization instead of cycloaddition? |
> I want to know whether an increase in temperature affects the enthalphy of dissolution?
It certainly can. You can treat the temperature dependence of dissolution with a formalism analogous to that applied to chemical reactions. The key parameter is the difference in heat capacity of the solid and dissolved solute... |
My textbook states the following:
> If a system were at absolute zero, an additional small amount of heat energy would lead to an infinite increase in entropy. Such a state is impossible. Absolute zero can never be achieved.
It also provides the equation:
$$ \Delta S_\text{surroundings} = \frac{-\Delta H_\text... |
I read that serine isn't strongly acidic so how is it that in serine proteases it is able to have its pKa lowered by the catalytic triad? |
How is serine ionized in serine proteases? |
In a section on **ionization efficiency and ionization cross section**, my mass spectrometry textbook says the following:
> The ionization energy represents the absolute minimum energy required for ionization of the neutral concerned. This means in turn that in order to effect ionization, the impacting electrons nee... |
Why do impacting electrons have a low probability of causing ionization? |
In a section on **ionization efficiency and ionization cross section**, my mass spectrometry textbook says the following:
> The ionization energy represents the absolute minimum energy required for ionization of the neutral concerned. This means in turn that in order to effect ionization, the impacting electrons nee... |
In a section on **ionization efficiency and ionization cross section**, my mass spectrometry textbook, *Mass Spectrometry* by Jürgen Gross, says the following:
> The ionization energy represents the absolute minimum energy required for ionization of the neutral concerned. This means in turn that in order to effect i... |
In a section on **ionization efficiency and ionization cross section**, my mass spectrometry textbook, *Mass Spectrometry* by Jürgen Gross \[1, pp. 38–39\], says the following:
> The ionization energy represents the absolute minimum energy required for ionization of the neutral concerned. This means in turn that in ... |
I recently read in a book that rain is considered [acid rain][1] if the pH falls below 5.6. However a substance is acidic when the pH is below 7; so why is the boundary for acid rain 5.6?
I was thinking pH between 5.6-7 would be too diluted to have an effect on limestone and other materials, and that's why the pH ha... |
Why is it considered acid rain with pH <5.6? |
i'm trying to mix my own liquid chalk, which is a simple mixture of chalk and a high percentage alcohol in a ~2 part chalk 1 part alcohol relation.
Unfortunately the smell is rather intensive and I would like to find a way to neutralize or cover it up.
Any suggestions?
I do not have a chemical backround. |
IUPAC “Green Book” recommends to use $\mathrm{sln}$ for denoting a solution in general \[1, p. 54\], referring to earlier *Recommendations 1981. Appendix No. IV to Manual of Symbols and Terminology for Physicochemical Quantities and Units* \[[2](https://doi.org/10/d783th), pp. 1240–1242\].
This has been extensively co... |
IUPAC “Green Book” recommends to use $\mathrm{sln}$ for denoting a solution in general \[1, p. 54\], referring to earlier *Recommendations 1981. Appendix No. IV to Manual of Symbols and Terminology for Physicochemical Quantities and Units* \[[2](https://doi.org/10/d783th), pp. 1240–1242\].
This has been extensively co... |
The Woodward-Hoffmann rules only tell you whether a reaction is thermally allowed or not, they do not give any indication of the relative rates of multiple allowed reactions.
I guess you're asking why the 4π component in a [4+2]-cycloaddition doesnt undergo a conrotatory 4π electrocyclic ring-closure? This is plausi... |
In the chapter on conjugation in *Organic Chemistry* by Clayden, Greeves, Warren and Wothers, there's a brief discussion of pigments with conjugated systems that includes the following paragraph (first edition, p. 171; emphasis mine):
>Transitions from bonding to antibonding π orbitals are called π → π* transitions.... |
Why do carbonyl groups lower antibonding orbital energies of conjugated systems? |
The image below is from a Nilered video [How to extract Vanillin from Vanilla Sugar](https://www.youtube.com/watch?v=DELgSlr5Eyw), where he displays the H NMR of the final product created:
[![nmr vanillin][1]][1]
The labels A, F & E make sense to me, but I'm confused about D and C - I feel they should be swappe... |
### Tryptophan
> For instance, is there a reason 'W' specifically was chosen for tryptophan (other than the fact that 'T' was taken)?
Once you have assigned the other 19 amino acids, there are only 7 letters of the alphabet left: B, J, O, U, W, X, and Z. (Certainly *not* a nice Scrabble hand to have!)
If one w... |
Some single letter codes that aren’t the amino acid’s starting letter actually make sense when viewed from certain angles. Here’s the list starting with the bloomin’ obvious:
- G — Glycine
- A — Alanine
- V — Valine
- L — Leucine
- I — Isoleucine
- P — Proline
- S — Serine
- T — Threonine
- C — Cyst... |
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... |
I’m an IT Acquisitions and Licensing specialist researching well-supported cloud software alternatives to Fujitsu’s molecular modeling [SCiGRESS][1]. I am coming in with a tech background, but little to none in chemistry, so I’m seeking the expertise of users of chemistry software.
While my online research has yield... |
Does a well-supported, cloud-based software alternative to Fujitsu's SCiGRESS exist? |
I’m an IT Acquisitions and Licensing specialist researching well-supported cloud software alternatives to Fujitsu’s molecular modeling [SCiGRESS][1]. I am coming in with a tech background, but little to none in chemistry, so I’m seeking the expertise of users of chemistry software.
While my online research has yield... |
Is there anyone here that had already analysed estrone and 17beta-estradiol on GC/MS (HP5-MS column and MSTFA as derivatizing agent)?
Is it necessary to make a misture of other reagents with MSTFA or I can use just MSTFA on the process of derivatization? And how long does that process take to happen? |
Which of the Following is Optically Active? |
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