Questions tagged [molecules]

An electrically neutral entity consisting of more than one atom (n > 1). Rigorously, a molecule, in which n > 1 must correspond to a depression on the potential energy surface that is deep enough to confine at least one vibrational state. This tag should be applied to question about certain molecules or a class of them.

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How many moles of sodium are there in 10mls of 30% sodium chloride?

How many moles of sodium are there in 10mls of 30% sodium chloride? 30% of 10mls is 3g NaCL. There is 3000mg of NaCl and would that be divided by the molecular weight of NaCl or of just Na? I ...
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phase differences between conical intersections and light-induced conical intersections?

I've read recently about light-induced conical intersections, a phenomenon where conical intersections can be artificially introduced to molecules, and that this can be observed even in diatomic ...
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Why is the discovery of chiral molecules in space a big accomplishment?

Today, I came across the discovery of a chiral pair of molecules in interstellar space. I know that a chiral molecule is a molecule that is not superimposable on its mirror image. But why is this ...
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Do cyclic oxygen molecules exist and their theoretical stability?

Do oxygen molecules ever become cyclic shapes like carbon and other elements? Why doesn't oxygen form cyclic compounds? How stable would they be if they do exist. Especially more than 3 oxygens. Why ...
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Why Use Lewis Structures to Determine Radicals

As far as I know, Lewis Structures are convenient for representing molecules, but give no insight on the actual electron orbitals. For example: The Lewis Structure of $\ce{O_2}$ does not reflect ...
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How does molecular orbital theory explain CH4? [closed]

I have understood the formation of $\ce{CH4}$ by valance bond theory, but I'm having trouble understanding it through molecular orbital theory. The energy level diagram of molecular orbitals of $\ce{...
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Why do the atoms in molecular models have the colors they have?

Molecular models are a great tool for visualizing a molecule in three-dimensional space. These models even appear on the web (practically every chemical's Wikipedia page), and there is a very specific ...
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Model of London forces and Hydrogen Bonding; the question is carried on forward, partially, as a personal question, from another question [closed]

Does Model of London forces and Hydrogen Bonding are themselves complicated and require multiple sub-models and assisted theories to explain its correctness. I asked this question in the form (...
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Dipole moment of molecule (isolated vs in solution)

Would you expect a dipole moment determined in solution to be different from that in an isolated molecule? If so, why?
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What are dipole moments in a molecule supposed to act upon?

In a $\ce{CO_2}$ molecule, a total of four electron pairs are shared between the carbon and oxygen atoms, such that 2 pairs are shared between the carbon atom and each oxygen atom. Oxygen has a ...
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How to quantize the shape of a molecule?

I am looking for numbers which tell you something about the 3D shape of the molecule, and is also easily calculated. One of these is the acentricity factor. I am aware of this one. My problem is you ...
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85 views

Colligative properties

I have some problems with these properties. 1) Lowering vapor pressure and boiling point. It happens because the solute molecules take space in the surface of the liquid so a lower number of the ...
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Do absorbances of different compounds at one wavelength sum up?

Question on my practice exam. The answers to the questions were not released, otherwise I could work backwards to figure out how to solve it. As it stands, though, I can only guess the method to solve ...
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why the formula of coca cola can not be find using chemistry? [duplicate]

i mean we have SPECTROSCOPY to stablish what molecules make a compound and also we have advanced chemistry so why is SO HARD to find the formula of coca cola ? simply buy a bottle examine it to ...
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Do symmetric hydrogen bonds in neutral molecules exist?

As far as I know, there have only few truly symmetric hydrogen bonds been observed. Unquestionable is the existence of it in the bifluoride ion, $\ce{[F-H-F]-}$, see also here. There are a couple of ...
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Why is an S-S bond stronger than an O-O bond?

I'm wondering why exactly the single bond between two sulfur atoms is stronger than that of two oxygen atoms. According to this page, an $\ce{O-O}$ bond has an enthalpy of $142~\mathrm{kJ~mol^{-1}}$, ...
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What exactly happens when vegetable oil is partially hydrogenated?

My current assumption is that partial hydrogenation requires a polyunsaturated fat, because partial implies at least one but not all, which means there must be at least two double bonds in the fat, ...
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Materials with solid volume greater than liquid volume

Water has a solid volume greater than its liquid volume. This question is in two parts. 1) Are there other materials that have solid volumes greater than liquid volumes? 2) What about the structure ...
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How can I search molecules by constituent atoms

Given a set of atoms, I would like to find (some / the most common) molecules that include only (some/all) atoms of the set. Is there any online search engine that can do this? E.g. Atoms={C,H} ...
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How to determine the empirical formula given mass percentages of the elements and the molecular weight?

A compound has $67.3 \% \rm~C,4.62 \%~N,6.93 \%~ H$ and O. Determine the molecular formula of the compound knowing its molar mass is $283\rm~\frac{g}{mol}$. My solution : The percentage for the ...
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Can you artificially create molecules with a machine?

Is it possible to create molecules with machines? For example: you shoot one oxygen-atom $(\ce O)$ on one diatomic hydrogen $(\ce{H2})$ to create one water molecule $(\ce{H2O})$.
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Stability of CN molecule

The $\ce{CN}$ molecule has been observed spectroscopically in comets where pressure has been estimated to be as low as $10^{-10}\ \mathrm{mmHg}$. Draw a Lewis structure for $\ce{CN}$. Suggest an ...
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How was the composition of DNA studied before the knowledge of its structure?

In a large polymer molecule (such as a DNA chain) which is made from multiple component monomers containing many atoms, how was it determined that the chain was made up from the four groups of ...
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In which cases do you say “oxide” when naming a molecule?

Based on the names of following molecules I got quite confused about the correct nomenclature: $\ce{NaHCO3}$ $\ce{K2SiO3}$ $\ce{PbCrO4}$ In none of the above molecule names you ever say "oxide" ...
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Is there a way to use free software to convert SMILES strings to structures?

So far I've been unsuccessful in finding an open source tool that will convert a large number (>100k) of SMILES strings to a chemical structure. Is this really only solved by commercial applications? ...
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Why is NO2 formed when N valency is 3

Sorry if the question is silly but this is troubling me more than enough. Here's what I know about chemical formula: Reverse the valencies of the combining elements. But in this case, $\ce{NO2}$ is ...
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Shouldn't all of group 16 form double bonds? [duplicate]

I notice that out of all of group 16 oxygen is the only element that can form a double bond. Why is that because shouldn't all of group 16 be able to form a double bond and be diatomic because they ...
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How is a side-group that contains a double bond named?

In my chemistry lecture, we are working on the naming and nomenclature of organic molecules. When we got to the naming of alkenes and alkynes, we were told that the functional group had to be in the ...
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Are the collisions between the real gas particles perfectly elastic?

Well my question is simple, if two real gas particles are colliding (head on collision) then will the kinetic energy will be conserved i.e. will it be a perfectly elastic collisions?
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Is this graphic of molecules correct?

First off, huge fan of chemistry, not a chemist – do be nice :D Would an image like this make sense as an infographic for the molecular composition of the air? I especially wonder if the different ...
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What would carbon-oxygen polymer be called?

So I have a chain molecule made of carbon and oxygen, and I'm not sure what it would be called. Would any of you lovely fellows be able to help me? The best name I've been able to come up with so far ...
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Can one component of a mixture penetrate the skin if the whole mixture cannot?

There's a general rule that says that compounds under 500 dalton are able to penetrate the skin without any special vehicle (such as ethanol). I've started using castor oil, which contains different ...
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Symmetrize nearly symmetric molecule

In the overall good paper of Beruski et. al.,[1] an algorithm of how to symmetrize an "almost symmetric" molecule by symmetrizing the distance matrix is given for the example of Methane. The ...
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How is the degree of unsaturation derived? [duplicate]

The formula for degrees of unsaturation is: $$1+ \frac{1}{2} \sum ( n_i (v_i-2))$$ $v_i$ = valency of atom $n_i$ = number of atoms with that valency Could someone explain how the formula works, ...
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Is water a heterogeneous molecule? [closed]

My question is based upon the statement found here: an element may be homogeneous on a larger scale, compared to being heterogeneous on a smaller scale. This is known as an effective medium ...
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Structure diagrams indicate plausible structures? [closed]

Structure diagrams have a hexagonal, "chicken wire" shape, which leads to more elegant representations of some molecules than others. For example, the following diagram must deviate from the usual ...
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Teaching: Two elements that make XY2 and XY4 molecules

I am not a chemist, but I will be explaining chemistry to some third-graders. I want to give the example of how different things can be made of the same parts, but arranged differently. My "real world"...
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What is the difference between “molecular mass”, “average atomic mass” and “molar mass”?

I don't understand the difference between "molecular mass" and "average atomic mass". They seem like the same thing to me. Is it that average atomic mass is just the weighted average of the "weights"/...
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Molarity of Sodium Ion Concentration (and some really weird answers…)

I know how to do this problem really easily but I don't know why my answer is wrong... The problem is: What is the molarity of sodium ions in a solution prepared by diluting $250\ \text{mL}$ of $0....
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Is there any molecule visualizing software for Python?

I am looking for a free and open-source software written or wrapped for Python that would simply allow me to generate bunch of figures (in eps, jpg, or pdf format) from a set of xyz files, e.g. water ...
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What is difference between intramolecular redox and disproportionation redox

I can not understand difference between the intramolecular redox reaction and the Disproportionation redox reaction. Both involve the same molecule as substrate, but what is difference?
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Molecules aren't the same as atoms?

Question is simple but tricky, for example my chemistry teacher says that preservatives on food for example Nitrate N3 are not good in excess for your body (like everything else), but if Nitrogen is ...
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If you can smell something does that mean that this thing loses molecules?

When you can smell something there must be some molecules in your nose which signalize the smell in your nose. Does that mean, that e.g. a cheese is losing molecules which fly into your nose? And does ...
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Good measures ot atomic size

I was looking up the Lennard-Jones parameter $\sigma$ (which, to my understanding, is a measure of molecular size) when I was surprised to discover that the value for the $\ce{N2}$ molecule (3.667 Å) ...
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Are long oxygen molecules possible?

Are large oxygen containing molecules possible? Either large rings, or chains with hydrogen atoms at the ends. Like this: $\ce{H-O-O-O-O-O-O-O-O-O-$\cdots$-O-O-O-O-O-H}$
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At what point does Avogadro's law not apply?

A mole of hydrogen gas takes up 22.4 L, but so does a larger molecule like $\ce{CO2}$. Methane ($\ce{CH4}$) is an even larger sized molecule, but a mole of it will still take up 22.4 L. I would assume ...
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Molecules made of molecules?

When a molecule of water ($\ce{H2O}$) and a molecule of hydrochloric acid ($\ce{HCl}$) react together, would they become a molecule made of molecules? What's the name for such thing? How would it be ...
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What makes water a liquid (when it is)?

I'm curious about what the minimal conditions for some collection of water molecules to be liquid water are. What is the minimum number? What sort of bonds must hold? What other sorts of things I don'...
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Why does SO2 have a larger bond angle than H2O, H2S, and NH3

So we have to find which of the follwing compounds has the smallest bond angle: $\ce{H2O}$, $\ce{H2S}$, $\ce{NH3}$, $\ce{SO2}$. So L $\propto \frac{1}{BA}$ where $L$ is the number of lone pairs and $...
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Identifying the number of bonding and lone pairs without a dot and cross diagram

I've just learned how to predict the shapes of molecules in class today using VSEPR theory. I would like to ask is there anyway to find the number of bond pairs and lone pairs without drawing a dot-...