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Which free radical is more stable, allyl free radical or benzyl free radical? |
I [read][1] that brewed tea contains a relatively large concentration of Fluorine.
Fluorine can have negative health effects such as [Skeletal Fluorosis][2]
Tap water and especially [hard water][3] contains lots of Calcium ions.
Would Calcium and Fluorine bond to form [Calcium Fluoride][4]? I'm obviously not a... |
As a non scientist I several times wondered how can an Organic chemist successfully isolate a single molecule which a natural product of an organism;<br>
Whether a plant-part/mushroom-part/algae-part or a coral-part or even from an animal or human organ in autopsy (neurotransmitter/hormone and so forth).
I also won... |
How can an Organic chemist know the chemical formula of a natural product she isolated from an organism? |
The thermal stability of alkaline earth metals increases down the group for hydroxides i-e., Be(OH)2 is less stable than Ba(OH)2.
The solubility also increases down the group for these compounds i-e., Be(OH)2 is less soluble in water as compared to Ba(OH)2. Hence for Hydroxides of group 2 elements the solubility and th... |
What is the relation between solubility and thermal stability? |
With MOPAC, I am trying to set up single run with geometry optimization followed by calculation of THERMOdynamic parameters.
Is there viable way for that ?
Thanks, Miro |
MOPAC: can we run THERMO immediately after the geometry optimzation? |
very Nobody is able to foresee the solubility of a product. There are some experimental rules, but they all have exceptions, that nobody is able to explain.
Just have a look on the Calcium salts made with the halogens (F, Cl, Br, I). There is a nice analogy among Cl, Br and I, but not F. Look ! The Calcium chloride... |
Nobody is able to foresee the solubility of a product. There are some experimental rules, but they all have exceptions, that nobody is able to explain.
Just have a look on the Calcium salts made with the halogens (F, Cl, Br, I). There is a nice analogy among Cl, Br and I, but not F. Look ! The Calcium chloride $\ce{... |
The third ortho effect is, according to Wikipedia, the phenomenon where in a ring with a meta and an ortho-para director both meta to each other has the incoming nucleophile go ortho to the meta director rather than para. Why is this? I would think that the ortho-to-meta position would be destabilized due to a stronger... |
I am currently studying *Mass Spectrometry: A Textbook*, third edition, by Jürgen H. Gross. On page 41, the author says the following:
> As explained by the Franck-Condon diagram, hardly any molecular ions will be generated in their vibrational ground state. Instead, the majority of the ions created by EI is vibrati... |
I am currently studying *Mass Spectrometry: A Textbook*, third edition, by Jürgen H. Gross. On page 41, the author says the following:
> As explained by the Franck-Condon diagram, hardly any molecular ions will be generated in their vibrational ground state. Instead, the majority of the ions created by EI is vibrati... |
With MOPAC, I am trying to set up single run with geometry optimization followed by calculation of THERMOdynamic parameters.
Is there viable way for that? |
I am currently writing a paper on the benzopyran below.
[![enter image description here][1]][1]
I am attempting to name the compound using IUPAC conventions. Because there is an aldehyde moiety, I suspect I will need to name the compound as a substituent of methanal (so 1-(substituent name)methanal). I could altern... |
I am measuring the dependence of electrical conductivity of ( NaCl and $\ce{CH3COONa}$ solutions with concentration 9g/L) with temperature using conductivity meter.
Theoretically the conductivity should decrease as the tempreture decrease, but unfortunately that does not seem to happen.
As you can see, as I start... |
Why does the electrical conductivity increase as the temperature decreases? |
I am currently writing a paper on the benzopyran below.
[![enter image description here][1]][1]
I am attempting to name the compound using IUPAC conventions. Because there is an aldehyde moiety, I suspect I will need to name the compound as a substituent of methanal (so 1-(substituent name)methanal). I could altern... |
I am measuring the dependence of electrical conductivity of ( NaCl and $\ce{CH3COONa}$ solutions with concentration 9g/L) with temperature using conductivity meter.
Theoretically the conductivity should decrease as the tempreture decrease, but unfortunately that does not seem to happen.
As you can see, as I start... |
> How can an Organic chemist know the *chemical formula* of a natural product she isolated from an organism?
There are two levels of answers. One is historical and one is modern. Historically, determining the chemical formula for has been a trivial job for most small or medium sized molecules. You do a combustion an... |
The standard reduction potential for $\ce{FeCO3_{(s)} + 2e- <=> Fe_{(s)} + CO3^2-}$ is $E^o=-0.756 \text{V}$, and the standard reduction potential for $\ce{Fe^2+ + 2e- <=> Fe_{(s)}}$ is $E^o = -0.44 \text{V}$.
From this, I calculated the $\ce{E^o}$ for the reaction $\ce{FeCO3_{(s)} <=> Fe^2+ + CO3^2-}$ to be $E^o = ... |
How can you have a reduction potential for a non redox reaction? |
It is known that allene (propadiene) $\ce{H2C=C=CH2}$ geometry is such that its hydrogen atoms are not in the same plane – do not form rectangle, but “extended tetrahedron”
![allene structure][1]
I wonder if structurally analogous carbon dioxide $\ce{O=C=O}$ exhibit similar geometry, i.e. do its lone electron pai... |
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 $$\ce{Fe^2+ + 2e- <=> Fe_{(s)}}\quad\quad\quad\quad\quad\quad (E^o = -0.44 \text{V})$$ are as given.
From these, I calculated th... |
> How can an Organic chemist know the *chemical formula* of a natural product she isolated from an organism?
There are two levels of answers. One is historical and one is modern. Historically, determining the chemical formula for has been a trivial job for most small or medium sized molecules. You do a combustion an... |
[![enter image description here][1]][1]
I am currently writing a paper on the benzopyran above.
I am attempting to name the compound using IUPAC conventions. Because there is an aldehyde moiety, I suspect I will need to name the compound as a substituent of methanal (so 1-(substituent name)methanal). I could alte... |
Previously, I was trying to understand why Al2O3 has a lower melting point than MgO. An answer on quora said: "Do not confuse the character of the bond between the metal and oxygen with the bonds between molecules in the compound. The polar character of the bonds between aluminum and oxygen is indeed less than between ... |
when Al2O3 melts which bonds are broken? |
> 1. Why is it unusual (as it seems to be implicitly implied) that the bond lengths of the molecular ion in its ground state somehow end up being larger than the bond lengths of the molecular ion in its vibrationally excited state?
It's not so much about whether the bond length in $\ce{M^.+}$ is *larger* or *smaller... |
Below I have drawn a molecule with random substituents $\ce{X}$ and $\ce{Y}$:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/3jf02.png
If the distances from $\ce{H_b}$ and $\ce{H_a}$ to $\ce{H_d}$ are considered, they are different - $\ce{H_b}$ is 5 bonds away and $\ce{H_a}$ is 3 bo... |
Below I have drawn a molecule with random substituents $\ce{X}$ and $\ce{Y}$:
[![enter image description here][1]][1]
If the distances from $\ce{H_b}$ and $\ce{H_a}$ to $\ce{H_d}$ are considered, they are different - $\ce{H_b}$ is 5 bonds away and $\ce{H_a}$ is 3 bonds away, so $\ce{H_b}$ sees $\ce{H_d}$ differ... |
> **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... |
I live in Bangkok and read [how water comes to customers here][1]:
I understand from the chart that water go through Thon Buri treatment plant (west Bangkok) and Mahasawat treatment plant (east Bangkok) before being pumped and transferred to the customer.
In the chart I clicked the links for these two treatment p... |
Generally, we know that triplet carbene is more stable than singlet. But in my book, it is written that singlet diflorocarbene is more stable than triplet diflorocarbene.
Can anyone tell the reason for it? |
Which is more stable? CF2 (singlet) or CF2 (triplet) |
Looking for random chemicals, I found a reference on the anion and thought that it could be synthesised from common laboratory reagents: 2Al + 2NaOH + 2H2O -> 2NaAlO2 + 3H2, NaAlO2 + 4HCl -> NaAlCl4 + 2H2O
The first reaction obviously occurs at high yield at STP. My question is- does the second reaction occur at STP or... |
Which of the following compounds reacts with ethyl magnesium bromide and also
decolorizes bromine water solution:
[![][1]][1]
[1]: https://i.stack.imgur.com/lCTt6.png
Is the answer only option (c)? |
Looking for random chemicals, I found a reference on the anion and thought that it could be synthesised from common laboratory reagents:
$$
\begin{align}
\ce{2 Al + 2 NaOH + 2 H2O &-> 2 NaAlO2 + 3 H2}\\
\ce{NaAlO2 + 4 HCl &-> NaAlCl4 + 2 H2O}
\end{align}
$$
The first reaction obviously occurs at high yield a... |
For aqueous solutions it is often assumed that 1mg / liter equals 1 ppm. Are there any guidelines up to which concentration this shortcut is admissible?
Are there any formulas which calculate the error when using this shortcut? |
"Parts per …" are dimensionless entities: to derive $\pu{ppm}$ from mass concentration $γ$ (e.g. $\pu{1 mg L-1})$ one uses density of water $\rho(\ce{H2O}) = \pu{1E6 mg L-1}$ for normalization:
$$\frac{γ}{ρ(\ce{H2O})} = \frac{\pu{1 mg L-1}}{\pu{1E6 mg L-1}} = \pu{1E-6} = \pu{1 ppm}$$
Once the solution is too conc... |
For aqueous solutions it is often assumed that 1 milligram per liter equals 1 ppm. Are there any guidelines up to which concentration this shortcut is admissible?
Are there any formulas which calculate the error when using this shortcut? |
Up to which dilution can one assume that 1 mg/l = 1 ppm? |
Previously, I was trying to understand why $\ce{Al2O3}$ has a lower melting point than MgO. An answer on quora said
>Do not confuse the character of the bond between the metal and oxygen with the bonds between molecules in the compound. The polar character of the bonds between aluminum and oxygen is indeed less than... |
Generally, we know that triplet carbene is more stable than singlet. But in my book, it is written that singlet difluorocarbene is more stable than triplet difluorocarbene.
What's the reason for it? |
The more common organoaluminum compounds, such as trialkylaluminum, decompose on contact with oxygen-containing molecules (water, ethanol etc). However, organoaluminum compounds with an aluminum atom being part of the aromatic system might be more stable towards oxygen compounds, since the high affinity for oxygen of a... |
Tetrafluoroborate salts, such as lithium tetrafluoroborate, are reasonably stable in aqueous solutions. Does the same hold for sodium tetrachloroaluminate as well or does it end up as NaAlCl4 + 4H2O -> NaAl(OH)4 + 4HCl? |
Do tetrachloroaluminate salts hydrolyse? |
The more common organoaluminum compounds, such as trialkylaluminum, decompose on contact with oxygen-containing molecules (water, ethanol etc). However, my guess is that organoaluminum compounds with an aluminum atom being part of the aromatic system might be more stable towards oxygen compounds, since the high affinit... |
Is the pyrolysis of tetrachloroaluminate(III) anion possible? |
Just hours ago, I asked a question about whether aromatic organoaluminum compounds with aluminum and carbon bonded together as part of an aromatic ring would be stable in water. The answer seemed to be that "it wouldn't even work at all since aluminum and carbon have relatively poor pi-overlap, and even then the result... |
Compounds with aluminum and nitrogen atoms directly bonded to each other as part of an aromatic ring? |
Well there is a pretty simple way, that you can do in any laboratory by standard reagents too
React the unknown mixture with ammonium hydroxide+ammonium chloride
(ammonium chloride is put as a standard to prevent the precipitation of Zn, Mn, Cu and Ni hydroxides, however, you don't have those in your sample, so you c... |
Well there is a pretty simple way, that you can do in any laboratory by standard reagents too.
React the unknown mixture with $\ce{NH4OH + NH4Cl}$
(ammonium chloride is put as a standard to prevent the precipitation of Zn, Mn, Cu and Ni hydroxides, however, you don't have those in your sample, so you can proceed with... |
I am a 12th grader, not even an undergrad, so I'll explain in the most colloquial way possible.
1. Internal energy is a state function
*A state function is a property whose value does not depend on the path taken to reach that specific function or value. ... Path functions are functions that depend on the path ta... |
Well there is a pretty simple way, that you can do in any laboratory by standard reagents too.
React the unknown mixture with $\ce{NH4OH + NH4Cl}$
(ammonium chloride is put as a standard to prevent the precipitation of Zn, Mn, Cu and Ni hydroxides, however, you don't have those in your sample, so you can proceed with... |
Tetrafluoroborate salts, such as lithium tetrafluoroborate, are reasonably stable in aqueous solutions. Does the same hold for sodium tetrachloroaluminate as well or does it end up as $$\ce{NaAlCl4 + 4H2O -> NaAl(OH)4 + 4HCl}?$$ |
I am a 12th grader, not even an undergrad, so I'll explain in the most colloquial way possible.
1. Internal energy is a state function.
*A state function is a property whose value does not depend on the path taken to reach that specific function or value. ... Path functions are functions that depend on the path t... |
I am a 12th grader, not even an undergrad, so I'll explain in the most colloquial way possible.
1. Internal energy is a state function.
*A state function is a property whose value does not depend on the path taken to reach that specific function or value. ... Path functions are functions that depend on the path t... |
I am a 12th grader, an undergrad, so I'll explain in the most colloquial way possible.
1. Internal energy is a state function.
*A state function is a property whose value does not depend on the path taken to reach that specific function or value. ... Path functions are functions that depend on the path taken to r... |
I am a 12th grader, so I'll explain in the most colloquial way possible.
1. Internal energy is a state function.
*A state function is a property whose value does not depend on the path taken to reach that specific function or value. ... Path functions are functions that depend on the path taken to reach that spec... |
I am a 12th grader, so I'll explain in the most colloquial way possible.
1. Internal energy is a state function.
*A state function is a property whose value does not depend on the path taken to reach that specific function or value. ... Path functions are functions that depend on the path taken to reach that spec... |
When attacking 3 degree alkyl halides, aren't both of them just supposed to follow SN2 and substitute the leaving group with Hydride ion? Apparently only NaBH<sub>4</sub> does it and LiAlH<sub>4</sub> causes an E1 elimination resulting in an alkene. Why does that happen? LiAlH<sub>4</sub> does reduce 2 and 1 degree alk... |
How is NaBH4 able to reduce 3 degree alkyl halides to alkane but LiAlH4 create an alkene? |
When attacking 3 degree alkyl halides, aren't both of them just supposed to follow SN2 and substitute the leaving group with Hydride ion? Apparently only NaBH<sub>4</sub> does it and LiAlH<sub>4</sub> causes an E1 elimination resulting in an alkene. Why does that happen? LiAlH<sub>4</sub> does reduce 2 and 1 degree alk... |
When attacking 3 degree alkyl halides, aren't both of them just supposed to follow SN2 and substitute the leaving group with Hydride ion? Apparently only NaBH<sub>4</sub> does it and LiAlH<sub>4</sub> causes an E1 elimination resulting in an alkene. Why does that happen? LiAlH<sub>4</sub> does reduce 2 and 1 degree alk... |
> How can an Organic chemist know the *chemical formula* of a natural product she isolated from an organism?
There are two levels of answers. One is historical and one is modern. Historically, determining the chemical formula for had been a trivial job for most small or medium sized molecules. You do a combustion an... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/eVlh4.png
I've recently came across this reaction and my guess is that firstly an amide forms that later reacts with the second amine group. Is this a general reaction? Does it matter if the compounds used are aromatic? |
According to my lecturer, if the geometry prevents planarization of the C-centre than an E1 is impossible. As chair and boat are the only stable conformations of a 6 membered ring of carbons, does this mean that such a ring can never undergo an E1?
Furthermore, why must the C-centre be planar for E1? I guess it all... |
I've recently came across this reaction and my guess is that firstly an amide forms that later reacts with the second amine group. Is this a general reaction? Does it matter if the compounds used are aromatic?
[![Reaction between benzene‐1,2‐diamine and picolinic acid yielding in 2‐(pyridin‐2‐yl)‐1H‐1,3‐benzodiazole... |
I'm trying to run Polarizable Continuum Model (PCM) calculations using the GAMESS(US) software. I'm not that well versed in what exactly these calculations are doing (beyond the whole, 'gas within a solvent cavity' explanation). So I will preface and say the calculations might be working and I am simply not understandi... |
The problem is as follows:
> A sealed container of $3\,L$ in capactity is filled with hydrogen and
> oxygen at $314\,torr$ each one at a temperature of $27^{\circ}C$. A
> spark produces the reaction between oxygen and hydrogen. Find the
> total pressure after the reaction supposing that the temperature does
> no... |
How does the vapor pressure in a vessel affects the total pressure after a combustion reaction? |
Why is high molar molar mass a requirement of good primary standards for volumetric analysis? |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/Mcf5W.gif
What will happen if I skip the addition of surfactant?
will the reaction happen only at the surface of the parent liquids? |
This practice is done in analytical chemistry in order to minimize the relative weighing error on the balance. Preferring a larger formula weight for a primary standard has nothing to do with impurity levels. We have to start with the highest purity standard.
For example, you wish to prepare a 0.010 M solution of o... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/I6ftq.png
I'm torn between options 1,3 and 4. I see those 3 all as correct. Can someone point to me which one might be right and why? |
Well there is a pretty simple way, that you can do in any laboratory by standard reagents too.
React the unknown mixture with $\ce{NH4OH + NH4Cl}$
(ammonium chloride is put as a standard to prevent the precipitation of Zn, Mn, Cu and Ni hydroxides, however, you don't have those in your sample, so you can proceed with... |
When attacking tertiary alkyl halides, aren't both of them just supposed to follow SN2 and substitute the leaving group with Hydride ion? Apparently only NaBH<sub>4</sub> does it and LiAlH<sub>4</sub> causes an E1 elimination resulting in an alkene. Why does that happen? LiAlH<sub>4</sub> does secondary and primary alk... |
How is NaBH4 able to reduce tertiary alkyl halides to alkane but LiAlH4 create an alkene? |
1060 g of urea aqueous solution is subjected to heating. It starts boiling at 100.53∘C. It is heated up to 102.12∘C. Amount of water vapourised in grams (Pure water boiling point is 100∘C, Kb of H2O is 0.53 K kg mol–1)
When water evaporates will the equivalent amount of urea also evaporate i.e. will we calculate ... |
1060 g of urea aqueous solution is subjected to heating. It starts boiling at 100.53∘C. It is heated up to 102.12∘C. Amount of water vapourised in grams (Pure water boiling point is 100∘C, Kb of H2O is 0.53 K kg mol–1)
When water evaporates will the equivalent amount of urea also evaporate i.e. will we calculate ... |
I'm confused exactly on how to use the concept of solubility to get the amount of separation from a certain solute in the solution.
This arises from attempting to solve a problem regarding this matter. The problem described is as follows:
> $400$ grams of anhydrous sodium sulphate ($Na_{2}SO_{4}$) is dissolved
>... |
I'm confused exactly on how to use the concept of solubility to get the amount of separation from a certain solute in the solution.
This arises from attempting to solve a problem regarding this matter. The problem described is as follows:
> $400$ grams of anhydrous sodium sulphate ($Na_{2}SO_{4}$) is dissolved
>... |
> [1 mark] To calculate the expansion work for a process,
> 1) the formula $w = -P_\mathrm{ex}(V_2 - V_1)$ always works under all conditions.
> 2) the formula $\mathrm dw = -P_\mathrm{ex}\,\mathrm dV$ can only be used for irreversible processes.
> 3) the formula $\mathrm dw = -P_\mathrm{ex}\,\mathrm dV$ always... |
"How can it remain secret?". Trivial answer is - it can't (it isn't).
WD40 is a Fast Moving Consumer Good (FMCG). It is also a reasonably cheap product - as an industrial chemist this suggests at least two things to me:
1. It doesn't contain anything rare or expensive
2. It isn't difficult to manufacture
As ... |
As stated in both the links Geoff and Philipp have kindly commented ([1][1], [2][2]) they are to do with symmetry labels we chemists like to assign to orbitals. Knowing an orbitals symmetry class can lead to a lot of simplifications down the road when you use quantum mechanical calculations and even dictate the reactiv... |
I know that the “$\mathrm{g}$” stands for symmetry of octahedral shape, but how are labels “1” and “2” given in $\mathrm{A_{1g}}$ and $\mathrm{A_{2g}}$ representations too…
Is it related to group theory? If so, then please elaborate.
|
During monochlorination of propane why is chloropropane the major product formed. As far as I know using free radical mechanism 2-chloropropane is the supposed to be formed as the secondary free radical is more stable than a primary free radical. But the calculations involving reactivity order of chlorination tell othe... |
Can you dissolve iodine without potassium iodide? |
> $\pu{1060 g}$ of urea aqueous solution is subjected to heating. It starts boiling at $\pu{100.53 °C}.$ It is heated up to $\pu{102.12 °C}.$ Find amount of water vapourised in grams. (Pure water boiling point is $\pu{100 °C},$ $K_\mathrm{b}$ of $\ce{H2O}$ is $\pu{0.53 K kg mol-1}.)$
When water evaporates will the ... |
When attacking tertiary alkyl halides, aren't both of them just supposed to follow SN2 and substitute the leaving group with Hydride ion? Apparently only NaBH<sub>4</sub> does it and LiAlH<sub>4</sub> causes an E1 elimination resulting in an alkene. Why does that happen? LiAlH<sub>4</sub> does secondary and primary alk... |
My lecturer said that the increasing flexibility of an alicyclic ring is an inherent property. I'm not entirely sure what they mean by flexibility. Number of feasible conformations? How far the bond angles can be away from non-ideal?
Is there an actual explanation for the increasing flexibility? |
Why are larger alicyclic rings more flexible? |
The answer is simple. You have a potentially much larger number of rotatable bonds between any two atoms. Cyclopropane is very inflexible, simply because every atom is joined to every other by a single bond. Each extra atom added to its ring gives you an extra pivot point about which the bonds can rotate.
So larg... |
My textbook says that the oxidation number of Oxygen in peroxides is -2, but when I searched up the internet, I found it to be -1. It could probably be a misprint in my book, but I am still not sure. Not only that, the oxidation number of Hydrogen in hydrides is said to be +1 in my book, when it's supposed to be, I bel... |
Oxidation number of Oxygen in peroxides: -2 or -1? |
My textbook says that the oxidation number of Oxygen in peroxides is -2, but when I searched up the internet, I found it to be -1. It could probably be a misprint in my book, but I am still not sure. Not only that, the oxidation number of Hydrogen in hydrides is said to be +1 in my book, when it's supposed to be, I bel... |
We know that an Oxygen atom has two lone pairs. Why doesn't oxygen then form coordinate covalent bonds using those since it has nothing to lose? |
Why doesn't Oxygen form coordinate covalent bonds? |
In my PhD-work, we are trying to develop LC-MS/MS methods for targeted analysis. Usually, I determine my quantifying ion/fragment based on a few different criteria:
* If there is a 13C internal standard of identical structure, stick with the same fragment for both.
* If not, look for the lowest noise/highest are... |
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