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I'm currently learning about orbital hybridization in carbon.
I see that carbon has an electron configuration of 1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>2</sup>.
However, there are actually three p-orbitals in the second shell, namely p<sub>*x*</sub>, p<sub>*y*</sub> and p<sub>*z*</sub>$, which could each hold two e... |
I'm currently learning about orbital hybridization in carbon.
I see that carbon has an electron configuration of 1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>2</sup>.
However, there are actually three p-orbitals in the second shell, namely p<sub>*x*</sub>, p<sub>*y*</sub> and p<sub>*z*</sub>, which could each hold two el... |
During a lecture, my professor told us that the probability $P$ to form a hydrogen molecule $\ce{H2}$ with mass number 3 could be calculated out of the abundances, $\gamma$, of the isotopes of this element: $\ce{^1H}$ (normal hydrogen), $\ce{^2H}$ (deuterium), etc. So,
$$
\begin{split}
P[\ce{H2}] &= P[(\ce{^1H} \c... |
During a lecture, my professor told us that the probability $P$ to form a hydrogen molecule $\ce{H2}$ with mass number 3 could be calculated out of the abundances, $\gamma$, of the isotopes of this element: $\ce{^1H}$ (normal hydrogen), $\ce{^2H}$ (deuterium), etc. So,
$$
\begin{split}
P[\ce{H2}] &= P[(\ce{^1H} \c... |
The answer comes in several layers, as Martin has alluded to. I'll try and give a short summary: each point goes slightly deeper than the previous one.
1. For an isolated atom, the labelling of the orbitals is arbitrary. That is to say, the $p_x$, $p_y$, and $p_z$ orbitals are all interchangeable. More formally, thi... |
The answer comes in several layers, as Martin has alluded to. I'll try and give a short summary: each point goes slightly deeper than the previous one.
1. For an isolated atom, the labelling of the orbitals is arbitrary. That is to say, the $p_x$, $p_y$, and $p_z$ orbitals are all interchangeable. More formally, thi... |
[Purine](https://en.wikipedia.org/wiki/Purine) is a remarkable substance, given Nature has chosen it as the scaffold for two nucleobases from [DNA/RNA](https://en.wikipedia.org/wiki/Nucleic_acid): [adenine (A)](https://en.wikipedia.org/wiki/Adenine) and [guanine (G)](https://en.wikipedia.org/wiki/Guanine). Its structur... |
What's special about the purine scaffold? |
>[...] we still put it in polar category
If you search for amino acid classification, you will find that there is no agreement on how to classify cysteine.
What you should know is that cysteine has different roles in proteins. In cysteine proteases, it acts as a nucleophile (and its surrounding often makes it mor... |
An optics supply company recommends using a dichloromethane solution to break bonds between optical elements joined with its UV-cured optical cement.[1] The page mentions that dichloromethane-based paint thinners also work. Use of dichloromethane in paint thinners has been phased out in the USA as of last year. Is the... |
What can be used as substitute to dichloromethane for breaking optical cement bonds? |
I recently learned that you can clean up latex paint wash-up water by flocculating it: adding aluminum sulfate and hydrated lime. I vaguely remember how flocculation works in clay slurries (change in pH changes the electrostatic charge on kaolin plates, causing them to attract and then precipitate). Does flocculation i... |
How does flocculation in paint work? |
Why do Rydberg atoms have electrons that can transition above the first ionization energy?
This can only happen in a multi-electron system but I don't see how the Rydberg formula would even work for n = infinity + 1. I thought it might have to do with the second ionization energy but the definition of that is just a... |
Why do Rydberg atoms have electrons that can transition above the first ionization energy? |
The internal energy of a system is in general not *only* a function of temperature. This means that holding the temperature constant does not guarantee that the energy will be constant. The statement that the energy is only a function of temperature applies to the particular case of ideal gases.
Assuming that gases ... |
I already did an IR frequency calculation for my molecule. Is there any possibility to just run a Raman frequency calculation with the chk file from my IR calculation? - or have I to do the calculation again with the freq=raman keyword? I checked the gaussian manual and found the raman=polar keyword. But I think this i... |
Gaussian16 Raman calculation from IR checkpoint file? |
The internal energy of a system is in general not *only* a function of temperature. This means that holding the temperature constant does not guarantee that the energy will be constant. The statement that the energy can be expressed as a function of only the temperature applies to the particular case of ideal gases.
... |
As [this video](https://www.youtube.com/watch?v=Xhps2HDpTwI) clearly confirms, the hydrolysis of SiCl4 is highly exothermic from breaking of chlorine bonds. The solution boils and solid insoluble Si(OH)4 is produced.
Also, [per Wikipedia](https://en.wikipedia.org/wiki/Silicon_tetrachloride) on the hydrolysis, to qu... |
I'm currently reading through Clayden's *Organic Chemistry*, and in chapter 30 an assertion is made that
> Halo aldehydes are unstable and should be avoided.
I should be clear that the context of this situation is under treatment with an enolate, so basic conditions are being employed. I believe the most likely h... |
Why are α-haloaldehydes unstable? |
An optics supply company recommends using a dichloromethane solution to break bonds between optical elements joined with its UV-cured optical cement.[1] The page mentions that dichloromethane-based paint strippers also work. Use of dichloromethane in paint strippers has been phased out in the USA as of last year. Is t... |
I have just carried a NMR experiment. This is about the parameters set during the experiment.
They are the **number of points (np)** and **tau**.
I think I kind of understand how np works;
> it's the discrete points of analogue FID that are being converted to
> digital points along with the FID signal envelop... |
I have just carried an inversion-recovery NMR experiment. This is about the parameters set during the experiment.
They are the **number of points (np)** and **tau**.
I think I kind of understand how np works;
> it's the discrete points of analogue FID that are being converted to
> digital points along with th... |
On Pg. 150 of Campbell’s Biology, on Concept 8.2, problem #3, the question is
>>“Some partygoers wear glow-in-the-dark necklaces that start glowing once they are “activated” by snapping the necklace. This allows two chemicals to react and emit light in the form of chemiluminescence. Is the reaction exergonic or ende... |
Transition state theory tells us that the rate constant of an elementary step is $$\ce{k_r=\frac{\kappa k_BT}{h}e^\frac{- \Delta G^\ddagger}{RT}}$$
where $\ce{\Delta G^\ddagger}$ is the activation free energy of the step i.e. the difference between the Gibbs free energy of the transition state, and the reactant stat... |
Can rate constant depend upon the concentration of reactants (or other species involved in the reaction)? |
I tried calculating the Index of Hydrogen Deficiency for C6H15SiCl, and I get negative one. I get this value by subtracting the number of chlorine and hydrogen atoms from that of the carbon atoms, and then adding one. I don't think I am supposed to do anything with the number of silicon atoms. Is this correct/normal? |
Negative DBE/Degree of Hydrogen Deficiency? |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/ECwVD.jpg
There is 1 $N_2$ molecule formed with 2atoms of nitrogen.
2N is 2 separate nitrogen atoms which have not formed any bond.Reasons could be that they didn’t get enough energy to form bond so they are present separately.
I want to confi... |
I read that (in cellular respiration) the transported electrons in NADH have a higher energy than those in FADH2.
I can't find a (simple or otherwise) explanation of what a "high-energy" electron is.
I came across a [question on Reddit][1] which asks the same question:
> I am not a chemist but I am trying to u... |
What are high-energy electrons? |
I read that (in cellular respiration) the transported electrons in NADH have a higher energy than those in FADH2.
I can't find a (simple or otherwise) explanation of what a "high-energy" electron is.
I came across a [question on Reddit][1] which asks the same question:
> I am not a chemist but I am trying to u... |
It is true that the identity operation belongs to every group, as the other answers point out. One can still ask, why don't we just omit the first column, by convention, since it is all ones anyway?
The simple answer is that it is not always all-ones. It gives important information, namely the dimension of the space... |
From *A Guidebook to mechanism in organic chemistry* by P. Sykes \[1, p. 155\]:
> The activating effect of $\ce{Y}$ on the nucleus is found to increase, i.e.
the overall rate of substitution increases, in the approximate order:
>
> $$\ce{OCOR} < \ce{NHCOR} < \ce{OR} < \ce{OH} < \ce{NH2} < \ce{NR2}$$
>
> $\ce{N... |
I already did an IR frequency calculation for my molecule. Is there any possibility to just run a Raman frequency calculation with the `chk` file from my IR calculation?
Or do I have to do the calculation again with the `freq=raman` keyword? I checked the Gaussian manual and found the `raman=polar` keyword, but I th... |
What could be the meaning of the red circles with letters **S** in them in the diagram below? I searched in the text but could not find.
From "[Role of TREK-1 in Health and Disease, Focus on the Central Nervous System][1]", Figure 2:
[![enter image description here][2]][2]
[1]: https://www.ncbi.nlm.nih.... |
What could these letters "S" in red circles mean in a biochemical diagram? |
> transported electrons in NADH have a higher energy than those in FADH2.
This is jargon describing the redox potential of the electron carrier NADH/NAD+ vs the electron carrier FADH2/FAD. So if you compare the two half reactions
$$\ce{NADH -> NAD+ + H+ + 2e-}\ \ \ \ \ \ E_\mathrm{red} = -0.320 V\tag{1}$$
$$\c... |
> transported electrons in NADH have a higher energy than those in FADH2.
This is jargon describing the redox potential of the electron carrier NADH/NAD+ vs the electron carrier FADH2/FAD. So if you compare the two half reactions
$$\ce{NADH -> NAD+ + H+ + 2e-}\ \ \ \ \ \ E_\mathrm{red} = -0.320 V\tag{1}$$
$$\c... |
> transported electrons in NADH have a higher energy than those in FADH2.
This is jargon describing the redox potential of the electron carrier NADH/NAD+ vs the electron carrier FADH2/FAD. So if you compare the two reduction half reactions
$$\ce{NAD+ + H+ + 2e- -> NADH}\ \ \ \ \ \ E^{\circ '}_\mathrm{red} = -0.32... |
I'm currently studying aromatic compounds via online recorded lectures, and my teacher brought up about cyclopropenol and cyclopropenylhydroxy while teaching carbocylic non benzenoid compounds. He said the latter exists while the former doesn't exist; and due to time restrictions they cut off the part where he explains... |
How come Cyclopropenylhydroxy exists and not cyclopropenol? |
I read somewhere before that some substances no longer crystallize naturally in some specific structures, although it do that readily before. Instead, new structures that never happen before become widespread.
So:
1. Is it true?
2. If it is true, what is this phenomenon called?
3. If it is true, what is some hig... |
Can a crystal structure of a substance appear or disappear? |
[![Screenshot of my lecture][1]][1]
I'm currently studying aromatic compounds via online recorded lectures, and my teacher brought up about cyclopropenol and cyclopropenylhydroxide while teaching carbocylic non benzenoid compounds. He said the latter exists while the former doesn't exist; and due to time restrictions ... |
How come Cyclopropenylhydroxide exists and not cyclopropenol? |
<h3>If the reduction potentials of two halfreactions are the same, is it still possible for them to run spontaneously under certain conditions?</h3>
At uni one question states:
**Could a redox reaction spontaneously occur among the
redox couples Aox/Ared and Box/Bred within non-standard circumstances if they hav... |
A question from the university course:
> Could a redox reaction spontaneously occur among the redox couples $\ce{A_{ox}}/\ce{A_{red}}$ and $\ce{B_{ox}}/\ce{B_{red}}$ within non-standard circumstances if they have the exact same standard reduction potentials? So then, under which conditions?
The lecturer used the ... |
Here I have an epoxide opening reaction, but I was wondering that when a nucleophile attacks, How would the stereochemistry work? I have 2 products I predicted and I'm not sure which one would be correct. It's either the first one predicted in the reaction of the second picture I have attached. Or are they actually the... |
I am really confused about rate law. From my understanding, the rate law gives an equation that tells us the rate of the disappearance of the reactants. So, for example, the rate law of the reaction 2NO+O2 --> 2NO2 is
----------
rate of disappearance of reactants =k*[NO]^2*[O2].
----------
Now, my ... |
I need a SMARTS string that matches the following critereon:
- It makes an aldehyde or a ketone only
- The target carbon is an alpha carbon
- The other alpha carbon must be more substituted (or be an aldehyde)
- The target carbon must not be more substited than a secondary carbon
I came up with the following s... |
I am really confused about the rate law. From my understanding, the rate law gives an equation that tells us the rate of the disappearance of the reactants. So, for example, the rate law of the reaction $\ce{2 NO + O2 -> 2 NO2}$ is as follows
$$\text{rate of disappearance of reactants} = k \, [\ce{NO}]^2 [\ce{O2}]$$... |
Ethanol has a boiling point of 78 ºC and ethanal 20 ºC. This is explained because between the ethanol molecules exist hydrogen bonds that are intermolecular forces stronger than the Van der Waals forces (dipole-dipole) that are established between the ethanal molecules.
But, why this is the case, as the ethanal mole... |
Why the hydrogen bonds are more intense than Van der Waals forces in the case where the molecules with the Van der Waals forces have a stronger dipolar momentum than the molecules with the hydrogen bond?
For example, ethanol (hydrogen bond) has a boiling point of 78 ºC and ethanal 20 ºC (Van der Waals forces) but th... |
Why hydrogen bonds are stronger than Van der Waals forces? |
*I am using a hypothetical case to explain my question*
Let us consider a chemical analysis method **A** (using a certain instrument), which is used to quantify the value of a particular species *b*. According the instrument manufacturer's notes, the instrument used needs to be calibrated once a month. I am analyzi... |
Does using same calibration curve for chemical analysis introduce correlation in sample error/uncertainty values? |
I'm just starting to study chemistry so sorry for the probably obvious question to you, guys.
According to [the definition of molecule in Wikipedia][1]:
> A molecule is an electrically neutral group of two or more atoms held
> together by chemical bonds.
According to that definition, I assume that parts of t... |
I got an unexpected reaction which I'm trying to explain to myself:
I mixed 10 parts glycerol with 1 part glycine at ~90C and to my great surprise the mixture turned from transparent to a tint of red. I had maybe 1-2% water in there too. There might have been a very slight evolution of gas but that most probably w... |
Red Compound from Glycine and Glycerol? |
Why the hydrogen bonds are more intense than Van der Waals forces in the case where the molecules with the Van der Waals forces have a stronger dipolar moment than the molecules with the hydrogen bond?
For example, ethanol (hydrogen bond) has a boiling point of 78 ºC and ethanal 20 ºC (Van der Waals forces) but thei... |
How do differences in molar mass affect the pressure-volume relationship between four different gases? |
Please note that calibrating an instrument once a month is another story as compared to constructing the calibration curve from that instrument. The former is meant to check the accuracy of the instrument's output and the latter serves to determine the concentration of a substance by noting the response of the instrume... |
I read somewhere before that some substances no longer crystallize naturally in some specific structures, although it do that readily before. Instead, new structures that never happen before become widespread.
Edit: @Buttonwood get the correct name for this phenomenon: disappearing polymorphs.
So:
1. Is it true... |
[![enter image description here][1]][1]
There is 1 $\ce{N2}$ molecule formed with 2 atoms of nitrogen.
2N is 2 separate nitrogen atoms which have not formed any bond.Reasons could be that they didn’t get enough energy to form bond so they are present separately.
I want to confirm is this right ?
[1]: ht... |
I've tried searching with Google as well as on this website, but I haven't been able to find even a question asking about it. It was something that I was just curious about, but my limited knowledge in Chemistry has prevented me from testing anything or realizing how to phrase my question in a way that an answer can be... |
Can Steel be Created from Germanium? |
First apologize for this kind silly question.One of my student ask me this question but I was unable to get a perfect answer from internet.Generally dilute HCl and impure zinc are using for hydrogen production in laboratory.My question is why do reaction stoped after some little time reaction?
Is it for coverup zin... |
Why do we not using concentrated HCl and zinc reaction to prepare hydrogen? |
First apologize for this kind silly question.One of my student ask me this question but I was unable to get a perfect answer from internet.Generally dilute HCl and impure zinc are using for hydrogen production in laboratory.My question is why do reaction stoped after some little time reaction?
Is it for coverup zin... |
In the [German Wikipedia Article on pH][1], I found the following formula for calculating the pH of weak acids (which are there defined of having $4.5 < pK_s < 9.5$:
$$c(H_3O^+)=c^0\cdot\sqrt{K_s\cdot c_0/c^0} \tag{1}$$
I am a bit confused about this as in school, I learned that the pH (or more precicely, the con... |
What is the difference between these two formulas for pH of weak acids? |
In the [German Wikipedia Article on pH][1], I found the following formula for calculating the pH of weak acids (which are there defined of having $4.5 < pK_a < 9.5$:
$$c(H_3O^+)=c^0\cdot\sqrt{K_a\cdot c_0/c^0} \tag{1}$$
I am a bit confused about this as in school, I learned that the pH (or more precicely, the con... |
I read that (in cellular respiration) the transported electrons in NADH have a higher energy than those in FADH2.
I can't find a (simple or otherwise) explanation of what a "high-energy" electron is.
I came across a [post on Reddit][1] which asks the same question:
> I am not a chemist but I am trying to under... |
My title may be confusing, so let me explain. Let's take the molecule SO2 for example...
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/HCq9k.jpg
Above, you can see that the Sulfur atom has 6 electrons from its original valence shell involved in bonding/in a lone pair. However, i... |
Do strong acids actually dissociate completely (every single molecule dissociates), or are they just assumed to do so for the sake of simplicity? That seems odd, considering weak acids, many of which are very similar to strong acids, don't fully dissociate. |
Do strong acids actually dissociate completely? |
Yes, for sufficiently strong acids, in sufficiently dilute conditions, in sufficiently basic solvents. However, things are hazier than you might expect, and depending on your definition, "clear-cut" examples of *complete* dissociation only become possible when you start swatting flies with nuclear bombs.
The problem... |
Yes, for sufficiently strong acids, in sufficiently dilute conditions, in sufficiently basic solvents. However, things are hazier than you might expect, and depending on your definition, "clear-cut" examples of *complete* dissociation only become possible when you start swatting flies with nuclear bombs.
The problem... |
Yes, for sufficiently strong acids, in sufficiently dilute conditions, in sufficiently basic solvents. However, things are hazier than you might expect, and depending on your definition, "clear-cut" examples of *complete* dissociation only become possible when you start swatting flies with nuclear bombs.
The problem... |
First apologize for this kind silly question.One of my student ask me this question but I was unable to get a perfect answer from internet.Generally dilute HCl and impure zinc are using for hydrogen production in laboratory.My question is why do reaction stoped after some little time reaction if we use pure zinc and c... |
My textbook says that hydrogen bonding is possible only when there is acidic hydrogen connected to an electronegative atom like $\ce{N}$, $\ce{O}$ or $\ce{F}$ and a basic lone pair of electrons on another electronegative atom.
Recently, when I was going through a material on organic chemistry online, I read that $\... |
Is it physically and chemically possible to design both a gas and a solid substance, such that there would be a technologically feasible initiation of a chain reaction analogous to the spark that starts a fire, with the unusual feature that the reaction cools the region?
We are familiar with a spark being applied to... |
In the [German Wikipedia article on $\mathrm{pH}$][1], I found the following formula for calculating the $\mathrm{pH}$ of weak acids (which are there defined of having $4.5 < \mathrm{p}K_\mathrm{a} < 9.5:$
$$c(\ce{H3O+}) = c^\circ\cdot\sqrt{K_\mathrm{a}\cdot c_0/c^\circ}\label{eqn:1}\tag{1}$$
I am a bit confused ... |
> transported electrons in $\ce{NADH}$ have a higher energy than those in $\ce{FADH2}.$
This is jargon describing the redox potential of the electron carrier $\ce{NADH}/\ce{NAD+}$ vs the electron carrier $\ce{FADH2}/\ce{FAD}.$ So if you compare the two reduction half reactions
$$
\begin{align}
\ce{NAD+ + H+ + 2... |
I recently came across the following in my OChem class:
Ethylene dichloride on reaction with NaI in acetone reacts via E2 mechanism to give ethene.
I have three questions:
1) Since it is an E2 mechanism, a strong base should be present, but the iodide ion is a weak conjugate base of its corresponding acid. So w... |
Is it physically and chemically possible to design both a gas and a solid substance, such that there would be a technologically feasible initiation of a chain reaction analogous to the spark that starts a fire, with the unusual feature that the reaction cools the region?
We are familiar with a spark being applied to... |
Thanks for some online resources (i.e. [here][1]) I have an understanding of what X-Ray Crystallography does.
By blasting X-Rays at a crystal and recording the scattering patterns on a plate behind the crystal, it becomes possible to determine the shape of the molecule in the crystal.
[![x-ray crystallography][2... |
How does X-Ray Crystallography determine the components (as opposed to the structure) of a molecule? |
That is because the solution to the structure isn't done just via the plate. The signal you see on the plate is what is called "form factors" of the experiment. They are associated with the fourier transform of the electron density. There are computational ways of obtaining the electron densiy once you have the form fa... |
According to [wikipedia][1]:
>... osmolarity takes into account the total concentration of penetrating solutes and non-penetrating solutes, whereas tonicity takes into account the total concentration of non-freely penetrating solutes only.
But if osmolarity has units of $ \frac{Osm}{L}$ shouldn't it include only ... |
Why does osmolarity take into account both penerating & non-penetrating solutes? |
According to [Wikipedia](https://en.wikipedia.org/wiki/Osmotic_concentration#Osmolarity_vs._tonicity):
> … osmolarity takes into account the total concentration of penetrating solutes and non-penetrating solutes, whereas tonicity takes into account the total concentration of non-freely penetrating solutes only.
B... |
Why does osmolarity take into account both penetrating and non-penetrating solutes? |
I've tried searching with Google as well as on this website, but I haven't been able to find even a question asking about it. It was something that I was just curious about, but my limited knowledge in Chemistry has prevented me from testing anything or realizing how to phrase my question in a way that an answer can be... |
I was watching a video of what would happen if the earth got kicked out of the solar system and at one point it was mentioned that oxygen and nitrogen snow would form. So would such snow be any different physically to good ol' water snow? Would it be more fine or less dense? I'm asking this because I'm thinking of writ... |
What would oxygen or nitrogen snow look like? |
So the electron density is the function $\rho(\vec x)$ that associates a value of electrons per cubic angstrom, to each point $\vec x$ in the 3D space.
This information tells us how likely it is to find electrons at specific regions of space within a system. Integrating $\rho$ over a particular volume $\mathcal{V}$ ... |
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