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As part of some research I am doing, I want to do a head-to-head comparison of software for generating 3D atomic coordinates for molecules. Is there a list anywhere of chemical software that does this?
I was able to settle on the following constraints: freely available, or at least free for academic users; can be ru... |
Being an exception of the Aufbau principle, Thorium has an electronic configuration of [Rn] 7s(2) 5f(0) 6d(2) instead of the expected [Rn] 7s(2) 5f(2) 6d(0).
Two other elements, Lanthanum and Actinium, also showed such an anomaly as 6s(2) 4f(0) 5d(1) and 7s(2) 5f(0) 6d(1) respectively. But we placed them both in the... |
Why is Thorium (At. no. 90) an f-block element at all? |
What is the dataset containing the largest molecules? |
What are datasets containing molecules with more than 28 heavy atoms? |
What are datasets containing molecules with more than 38 heavy atoms? |
I am following the computational method described in this [paper][1]. Where the authors analyze the contribution of each excited state normal-modes to the shift of the transition energy. For this calculation they use the force constants of each normal mode.
I am using ORCA but could not understand how to generate the ... |
I realized that liquids like petrol, kerosene and even perfumes, where combustible then they are volatile. Could that be the reason why water is not combustible, because it is not volatile? |
Being an exception of the Aufbau principle, Thorium has an electronic configuration of $\ce{[Rn]}\mathrm{7s^25f^06d^2}$ instead of the expected $\ce{[Rn]}\mathrm{7s^2 5f^2 6d^0}$.
Two other elements, Lanthanum and Actinium, also showed such an anomaly as $\mathrm{6s^2 4f^0 5d^1}$ and $\mathrm{7s^2 5f^0 6d^1}$, respe... |
$$\ce{IO3-(aq) + 5I-(aq) + 6H+(aq) -> 3I2(aq) + 3H2O(l)}$$
Why does the reaction between iodide and iodate ions have to occur in an acidic medium ($\ce{H+}$) to form the iodine? what do the $\ce{H+}$ ions react with?
|
**Many volatile liquids are not combustible**
Dichloromethane (DCM) is a widely used solvent by chemists. It boils at around 40°C (the same as diethyl ether) but is not remotely combustible or flammable. Ether is both very volatile and very flammable, so much so that most labs would prefer not to have it used anywhe... |
This Thorlabs part [here][1] uses a material that absorbs only NIR and emits in visible. The spec sheets don't list what chemical this is. Do you know materials that show similar emission properties even with weak laser excitation?
[1]: https://www.thorlabs.com/drawings/acbe94fcb7187ab9-935558D0-050E-5735-7E82B6... |
Volatility ( even if by thermal decomposition ) is the necessary, but not sufficient condition for liquids to be combusted, forming a flame.
Liquid helium is the most volatile liquid ever, but there is no way to burn it ( chemically ).
As other answers mention, there is correlation, as flammable liquids are generally... |
I'm stuck with this question:
Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf?
I've thought that it might have something to do with how the sunlight emits at different wavelenghts, in the green wavlength of 565 especially (as the sun itself is green), and therefore with e... |
Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf? |
I am following the computational method described in *Scientific Reports*.<sup>\[1\]</sup> Where the authors analyze the contribution of each excited state normal-modes to the shift of the transition energy. For this calculation they use the force constants of each normal mode.
I am using ORCA but could not understa... |
How to extract force constants for normal modes from ORCA? |
Well, it may not sound deeply related to chemistry but my question is to some chemistry-experts who knows bit about automobile industry.
I want to ask, if a person is getting graduated by having studied all the chemistry majors and he/she wants to get into any field related to automobile industry or cars to be preci... |
Of course the first thing to come to my mind is fuel technology. For example st1 makes [fuel from waste][1]. I'm pretty sure that tire development also need chemistry in rubber compounds. In addition catalytic converter development needs chemistry because their purpose is to cause reactions.
So as a whole I would say t... |
Is it possible to have an allotrope of carbon with formula $\ce{(=C=)_n}$?
Well, let's actually leave alone the separate question like from which "monomer" would one produce such a thing (can one actually consider it being a polymer? Or a covalent crystal?), because it seems like the most suitable candidate would be... |
Is it possible to have an allotrope of carbon as a long unbranched chain of itself? |
Is there a formula or method for calculating the net charge of an amino acid at different pH's? I KNOW how to assign and calculate the general/average charge (-1, 0, 1, etc.) *but I need more precise values for each group* because of taking into account partial charges. I believe I need to use the Henderson-Hasselbalch... |
How do I calculate total net charge of an amino acid? |
Well I was wondering why adenine pairs with thymine and cytosine pairs with guanine.
From those pictures:
[![enter image description here][1]][1]
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/CNlwh.png
[2]: https://i.stack.imgur.com/Qisay.png
Thymine is has the lowest ... |
Well I was wondering why adenine pairs with thymine and cytosine pairs with guanine.
From those pictures:
[![enter image description here][1]][1]
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/CNlwh.png
[2]: https://i.stack.imgur.com/Qisay.png
Thymine has the lowest aci... |
This Thorlabs VRC4 card [here][1] uses a material that absorbs only NIR and emits in visible. The spec sheets don't list what chemical this is. Do you know materials that show similar emission properties even with weak laser excitation?
[1]: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=296 |
Is there a formula or method for calculating the net charge of an amino acid at different pH's? I KNOW how to assign and calculate the general/most common charge (-1, 0, 1, etc.) *but I need more precise values for each group* because of taking into account mixed protonation states (e.g. 40% protonated and 60% deproton... |
How do I calculate average net charge of an amino acid at given pH? |
Well I was wondering why adenine pairs with thymine and cytosine pairs with guanine.
From those pictures:
[![enter image description here][1]][1]
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/CNlwh.png
[2]: https://i.stack.imgur.com/Qisay.png
Thymine has the lowest aci... |
Is there any mathematical or logical proof that carbon with 4 different groups would be chiral? |
It's been a while since I've dealt with these, but do character tables include all possible symmetry operations?
I am looking at the $D_{\infty h}$ point group table and it lists $C_\infty$, $\sigma_v$, $S_\infty$, $i$, and $C_2$. But doesn't it also have a $\sigma_h$? Why is this not included?
Am I missing some... |
> I want to ask, if a person is getting graduated by having studied all the chemistry majors and he/she wants to get into any field related to automobile industry or cars to be precise. What would they be?
Paints, adhesives, polymers => Polymer Science/ Organic Chemistry. Adhesives is a big industry
Corrosion pro... |
I'm looking into anodization, and all the people doing it seem to have sulfuric acid as their first choice electrolyte, while others use sodium metabisulfate. Having simple access to exactly neither of these, I was wondering.
1. Why is sulfuric acid important?
2. Can I use more accessable (and safer) electrolytes... |
I was learning about group 14 of the periodic table and in the course, on Alison (link at the bottom), it said a reaction of the elements in group 14, they use group 4, would consist of sharing electrons. They explained it to what I believe is from going to 2,8,4, Silicon, to 2,4,8 in order to get the full shell. I am ... |
I am told that Q = F x n where Q is the quantity of current, F is Faraday's constant and n is the amount electrons. Since Faraday's constant is the charge carried by 1 mol of electrons, multiplying it by the number of moles of electrons to give the total charge makes perfect sense. But why does dividing Q by nF give th... |
Why is Q/nF equivalent to the amount of substance in electrolysis? |
What is the cause of yellow discharge in beaker during the electrolysis of copper electrodes using copper sulfate electrolyte? |
I have noticed it frequently and decided to check with some of my peers and friends about this and they too have felt such a thing.
The taste comparison occurs after the boiled water is cooled down to room temperature.
My question is: does water even have a taste?
And whether heating it may change the taste. |
Why does boiled water have a different taste as compared to cool water? |
How can I know that a given reaction is endothermic or exothermic. I know that all combustion reactions are exothermic. But what about other reactions?
In my school exam I was asked about whether the reaction $N_2+O_2 \rightarrow 2NO$ is exothermic or endothermic. I didn't know that it is endothermic reaction and le... |
I am told that
$$Q = nF$$
where $Q$ is the quantity of current, $n$ is the amount of electrons and $F$ is Faraday's constant. Since Faraday's constant is the charge carried by 1 mol of electrons, multiplying it by the amount of electrons to give the total charge makes perfect sense. But why does dividing $Q$ by $... |
How can I know that a given reaction is endothermic or exothermic? I know that all combustion reactions are exothermic. But what about other reactions?
In my school exam I was asked about whether the reaction
$$\ce{N2 + O2 -> 2 NO}$$
is exothermic or endothermic. I didn't know that it is endothermic reaction a... |
**Many volatile liquids are not combustible**
Dichloromethane (DCM) is a widely used solvent by chemists. It boils at around 40°C (the same as diethyl ether) but is not remotely combustible or flammable. Ether is both very volatile and very flammable, so much so that most labs would prefer not to have it used anywhe... |
I realized that liquids like petrol, kerosene and even perfumes are combustible when they are volatile.
Could that be the reason why water is not combustible is because it is not volatile?
Are volatile liquids all combustible? |
Being an exception of the Aufbau principle, Thorium has an electronic configuration of $\ce{[Rn]}\mathrm{7s^25f^06d^2}$ instead of the expected $\ce{[Rn]}\mathrm{7s^2 5f^2 6d^0}$.
Two other elements, Lanthanum and Actinium, also showed such an anomaly as $\mathrm{6s^2 4f^0 5d^1}$ and $\mathrm{7s^2 5f^0 6d^1}$, respe... |
I work in a laboratory where gas chromatography is used extensively. We handle phthalates. what are the possible wash solvent for autosampler syringe? I've been using acetone |
I work in a laboratory where gas chromatography is used extensively. We handle phthalates. What are the possible wash solvent for autosampler syringe? I've been using acetone. |
**Question:**
$CaCO_3$ dissociated in a closed system according to the reaction:$CaCO_3(s)=CaO(s)+CO_2(g)$.Assuming the reaction is in thermodynamic equilibrium what is/are the degree(s) of freedom?
**Doubt:**
I tried applying the condensed phase rule.All that I could arrive at was C-P+1=3-2+1=2.However the answer... |
What is the degree of freedom of the reaction? |
### Question
> $\ce{CaCO3}$ dissociated in a closed system according to the reaction:
> $$\ce{CaCO3(s) -> CaO(s) + CO2(g)}$$
> Assuming the reaction is in thermodynamic equilibrium, what is/are the degree(s) of freedom?
### Doubt
I tried applying the condensed phase rule. All that I could arrive at was
... |
What is the degree of freedom of the calcium carbonate dissociation reaction? |
Sometime ago I had posted the [What is the origin of "normal" in normal coordinates and normal modes?][1] in math & sci history problems. Nobody was sure for the reason for using the word *normal* there - it was an interesting discussion though. The concept of normal coordinates is transiently brought in vibrational sp... |
Different regions on the electromagnetic spectrum has different activity on matter.
Microwave can induce molecular rotation, Infrared can induce Molecular vibration, Visible and Ultra-violet light can induce electron excitation, and X-ray and Gamma ray can induce ionization.
Is there any activity specific only t... |
What are the effects of Radio waves on matter? |
Why there are more examples of carbonylate anions than metal carbonyl cations? |
I'm stumped by this question:
>Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf?
I've thought that it might have something to do with how sun emits light at different wavelengths, in the green wavelength of 565 especially (as the sun emits green light), and therefore, th... |
At times I find the concentrations being expressed as weight percentage.However I do not understand why molarity is not chosen.
Secondly,which close reference to the problem that I have been facing this is a follow up question:
The change of standard state from pure liquid to 1 wt % for Si dissolved in liquid Fe at... |
At times I find the concentrations being expressed as weight percentage. However I do not understand why molarity is not chosen.
Secondly, which close reference to the problem that I have been facing this is a follow up question:
>The change of standard state from pure liquid to 1 wt % for Si dissolved in liquid ... |
I was learning about group 14 of the periodic table and in the course, on Alison (link at the bottom), it said a reaction of the elements in group 14, they use group 4, would consist of sharing electrons. They explained it to what I believe is from going to 2,8,4, Silicon, to 2,4,8 in order to get the full shell. I am ... |
How do they allow for better separation? For example, why isn't 100% hexane used? |
In High Performance Liquid Chromaotgraphy, why are ratios of solvents used? |
In High Performance Liquid Chromatography, why are ratios of solvents used? |
Not sure if I can fulfill Ed's "real answer". I like the word you used for tuning solvent polarity- a knob. Modern student may understand this better.
There is no theoretical restriction in chromatography to use multiple solvents or a single solvent. For example in gas chromatography, you always use a pure gas. The ... |
Not sure if I can fulfill Ed's "real answer". I like the word you used for tuning solvent polarity- a knob. Modern students may understand this better.
There is no theoretical restriction in chromatography to use multiple solvents or a single solvent. For example in gas chromatography, you always use a pure gas. The... |
Sometime ago I had posted the [What is the origin of "normal" in normal coordinates and normal modes?][1] in math & sci history problems. Nobody was sure for the reason for using the word *normal* there - it was an interesting discussion though. The concept of normal coordinates is transiently brought in vibrational sp... |
# Summary: RDKit ETKDG is currently the best open source tool
This is an interesting question, since a reviewer just asked us to do such a benchmark.
The trick is that there's a fine distinction between "generating 3D coordinates" (i.e., one conformation) and "generating 3D coordinates and doing some conformer sa... |
A/c to me, Mg will be more hydrated and so should have lesser conductivity.Is tht correct? |
Out of CaCO3 and MgCO3 which has higher electrical conductivity of molten solution? |
Do you really think molten inorganic salts will have a trace of water? Second question is do these carbonates melt? Don't mix molten state with aqueous state. No correlation.
When these compounds are heated both MgO and CaO are formed releasing carbon dioxide. They don't like to melt at all. Have you heard of limeli... |
In my project, there are some spin forbidden organometallic reactions that involves both the triplet minima and singlet transition state (TS). Using the penalty method in qchem as well the method of Harvey, two candidate structures of the minimum energy crossing point (MECP) were identified. However, these two structur... |
IRC analogue of conical intersections and minimum energy crossing points? |
In Flame Emission Spectroscopy, what part of the flame is used to measure the concentration of the analyte? |
What is the point group of of cis and trans decalin? I watched a video saying that it is C2h for cis isomer, but my friend says it is D2h. I'm sooo confused. Thank you so much. |
According to me, Mg will be more hydrated and so should have lesser conductivity. Is that correct? |
Out of CaCO3 and MgCO3, which has higher electrical conductivity of molten solution? |
Are all volatile liquids combustible? |
What is the point group of of *cis*- and *trans*-decalin? I watched a video saying that it is $C_\mathrm{2h}$ for *cis*-isomer, but my friend says it is $D_\mathrm{2h}.$ I'm so confused. |
I live in Florida, an incredibly wet environment where it's very difficult to get moisture out of house without using a dehumidifier 24/7, which is too expensive. Would charcoal briquettes be of any use? |
Will charcoal briquettes (not activated) absorb water out of the air in the house in a subtropical climate? |
I've read quite a few other answers on this site such as [this one][1], but can't quite seem to understand fully yet.
Say we have a container with gases reacting such that the number of moles on both sides of the equation are not equal. If we then, for instance, reduce the volume of the container, the total pressure... |
I've read quite a few other answers on this site such as [this one][1], but can't quite seem to understand fully yet.
Say we have a container with gases reacting such that the number of moles on both sides of the equation are not equal. If we then, for instance, reduce the volume of the container, the total pressure... |
"Molten" here probably means "liquid". While the carbonates gave too little solubility to be considered for electrolyte, we can compare the conductances of $\ce{Ca^{2+}$ and $\ce{Mg^{2+}$ in dilute solution. In [this reference](https://www.google.com/url?sa=t&source=web&rct=j&url=https://pubs.usgs.gov/wsp/2311/report... |
> Will these changes result in the molar mass of a substance no longer being exactly equal to the molecular mass expressed in grams?
Yes. The ratio between the two is called the molar mass constant, and it used to be 1 g/mol exactly. Now that Avogadro's constant is set to a fixed value, it's value has to be determin... |
**"Shifting" an equilibrium**
Unfortunately for learners of chemistry, statements like "the equilibrium shifts to the right" are quite common jargon.
What is meant by this, speaking in more accurate technical terms, is the following: A reaction had reached equilibrium (net reaction is zero), and then some change ... |
[![Phase diagram of LNG][1]][1]I'm developing a piece of software which calculates and plots the Phase diagram (PT) for a mixed component natural gas.
For reference I have a common used natural gas plotted using a commercial software. See image above. The Bubble curve is purple and ends at the critical point. Dew cu... |
What is the point group of of *cis*- and *trans*-decalin?
[![enter image description here][1]][1]
I watched a video saying that it is $C_\mathrm{2h}$ for *cis*-isomer, but my friend says it is $D_\mathrm{2h}.$ I'm so confused.
[1]: https://i.stack.imgur.com/h6lNa.jpg |
"Molten" here probably means "liquid". While the carbonates gave too little solubility to be considered for electrolyte, we can compare the conductances of $\ce{Ca^{2+}}$ and $\ce{Mg^{2+}}$ in dilute solution. In [this reference](https://www.google.com/url?sa=t&source=web&rct=j&url=https://pubs.usgs.gov/wsp/2311/repo... |
Here is a view of cis-decalin with the bridging C-C bond in the plane of the paper:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/T5i5Ym.jpg
(It was made using the Jmol software, e.g. at https://chemapps.stolaf.edu/jmol/jsmol/simple.htm using the "Load by name" button and entering ... |
What is the point group of of *cis*- and *trans*-decalin?
[![enter image description here][1]][1]
I watched a video saying that it is $C_\mathrm{2h}$ for *cis*-isomer, but my friend says it is $D_\mathrm{2h}.$ I'm so confused.
[1]: https://i.stack.imgur.com/26whH.jpg |
**cis-Decalin**
Here is a view of cis-decalin with the bridging C-C bond in the plane of the paper:
[![enter image description here][1]][1]
(It was made using the Jmol software, e.g. at https://chemapps.stolaf.edu/jmol/jsmol/simple.htm using the "Load by name" button and entering "cis-decalin".) At https://w... |
**cis-Decalin**
Here is a view of cis-decalin with the bridging C-C bond in the plane of the paper:
[![enter image description here][1]][1]
(It was made using the Jmol software, e.g. at https://chemapps.stolaf.edu/jmol/jsmol/simple.htm using the "Load by name" button and entering "cis-decalin".) At https://w... |
I saw C-H bond is stronger than C-C bond... Is this because of the following reasons?
1) C-H bond is shorter than C-C bond.
2) C-H bond is more ionic than C-C bond.
I feel it a bit counterintuitive because we know that p-p overlap is stronger than s-p overlap OF SAME PRINCIPLE NUMBER is this the mistake I am doing? Co... |
> Will these changes result in the molar mass of a substance no longer being exactly equal to the molecular mass expressed in grams?
Yes. The ratio between the molar mass and the relative molecular mass is called the molar mass constant, and it used to be 1 g/mol exactly. Now that Avogadro's constant is set to a fix... |
> Will these changes result in the molar mass of a substance no longer being exactly equal to the molecular mass expressed in grams?
Yes. The ratio between the molar mass and the relative molecular mass is called the molar mass constant, and it used to be 1 g/mol exactly. Now that Avogadro's constant is set to a fix... |
I saw C-H bond is stronger than C-C bond... Is this because of the following reasons?
1) C-H bond is shorter than C-C bond.
2) C-H bond is more ionic than C-C bond.
I |
Why doesn't acetone have high basicity?
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/kpkJ8.png
The C-O bond is polar, O becomes partially negatively charged and it should attract protons, becoming a strong base.
|
Why doesn't acetone have high basicity?
[![acetone][1]][1]
The C−O bond is polar, O becomes partially negatively charged and it should attract protons, becoming a strong base.
[1]: https://i.stack.imgur.com/gcpW0.png |
In many Chemistry books dipole moment of molecules is calculated through algebraic formulas. But another definition of dipole moment is $\vec{\mu} = \sum_i q_i \, \vec{r}_i$ . So how can we calculate dipole moment of water for example using this formula? Is there a difference in interpretation of dipole moment in Physi... |
Avogadro's constant $N_\mathrm A$ is defined as the number of constituent particles (usually atoms or molecules) contained in the amount of substance given by one mole.
The value of Avogadro's constant $N_\mathrm A$ is going to be set to *exactly* $6.02214076\times 10^{23}\ \mathrm{mol}^{-1}$ in 2019.
I might ad... |
I operate in a wastewater treatment plant laboratory and I use respirometric method for BOD5 measurement. Recently I am obtaining high value for BOD for example BOD5 581 mg/L when the COD of the same sample 895 mg/L. I did multiple essays on another sample and I obtained different values for the same sample using the s... |
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