instruction stringlengths 15 21.8k |
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>A glass vessel weighs $\pu{20.2367 g}$ when empty and $\pu{20.3102 g}$ when filled to the etched mark with water at $\pu{4 °C}$. The same vessel was then dried and filled to the same mark with a solution at $\pu{4 °C}$, the vessel was now found to weigh $\pu{20.3300 g}$. What is the density of the solution? (Assume th... |
Does entropy of the universe always increase in one of the forward or backward reactions of a reversible reaction and decrease in the other?
If no then how do you explain the entropy of the universe increasing in both directions or decreasing in both directions?!?
If yes, do we get more of the reaction that incre... |
What is the purpose of the atomisation process in atomic absorption spectroscopy?
I understand that solution is evaporated by the flame and then the molecules decompose into atoms.
But why must the molecules become individual atoms before the light is passed through them? |
What is the purpose of atomisation in atomic absorption spectroscopy? |
To start with your first sentence: "Why can a wavefunction be written as a product of 1-electron wave-functions"? Well, you *can* write whatever you want to approximate a wavefunction; physics police is not going to come and take you away. But the two important questions are: How useful will the results from your appro... |
What will be the name of CH2=CH-O-CO-CH3? |
Why doesn't H3CO3 exist and why doesn't the carbonyl group in carbonic acid (H2CO3) seem reactive? |
In the following I limit discussion to the particular expression $$ΔU = ΔH - pΔV$$
which follows (spoiler alert) from $$H\equiv U+pV$$ when the pressure $p$ of the system (the container) is identical at the beginning and end of the process.
> 1. Is the pressure outside the container assumed to always be constant?
... |
I had a mug of packaged pudding. The top layer of the pudding was of typical pudding consistency, while the bottom was more runny. What could have caused this? |
Question about the properties of starch in packaged pudding? |
In the following I limit discussion to the particular expression $$ΔU = ΔH - pΔV$$
which follows (spoiler alert) from $$H\equiv U+pV$$ when the pressure $p$ of the system (the container) is identical at the beginning and end of the process.
> 1. Is the pressure outside the container assumed to always be constant?
... |
Atomic absorption spectroscopy is a quantitative measure of the elements in the analyte.
We atomise the analyte so that the absorption of light corresponds to the characteristics of the elements.
Otherwise how we can predict the fundamental elements when these are still part of some molecules?
We measure the absorb... |
I know crown ethers can be used to complex metal ions.
__Question__: What important properties do 18-crown-6 change during the benzannulation from 18-crown-6 to DB18C6 (dibenzo-18-crown-6)? How do these change?
(Disclaimer: I know that DB18C6 does not necessary to be synthesised from 18C6)
Motivation: I saw th... |
$\ce{H3CO3}$ does not exist. Why should it exist ? Where does this formula come from ? Of course you are allowed to write any formula you want. It is not forbidden to write $\ce{HC4O3}$ $\ce{H3CO5}$ $\ce{H3C2O3}$ or any other combination of C, H and O atoms that you may think of. Just for fun ! But Nature ignores your ... |
$\ce{H3CO3}$ does not exist. Why should it exist ? Where does this formula come from ? Of course you are allowed to write any formula you want. It is not forbidden to write $\ce{HC4O3}$ $\ce{H3CO5}$ $\ce{H3C2O3}$ or any other combination of C, H and O atoms that you may think of. Just for fun ! But Nature ignores your ... |
What is the difference between dynamical and non-dynamical correlation and which one is accounted for in Hartree-Fock theory? |
Why doesn't $\ce{H3CO3}$ exist and why doesn't the carbonyl group in carbonic acid $(\ce{H2CO3})$ seem reactive? |
Does H3CO3 exist and what is its structure? |
To dissolve branded food from e. g. a baking tray, there is the advice to pour table salt on it and heat it up in a baking oven or on a hotplate until the salt turns brown. I practiced it and it works.
But I'd like to know why it works. Can anybody please explain it in layman's terms? What reaction(s) happen(s) there? |
Why does table salt (NaCl) dissolve branded food? |
In comments below [this answer](https://space.stackexchange.com/q/40189/12102) in Space Exploration SE [I've said](https://space.stackexchange.com/questions/40189/lantr-has-been-proposed-why-not-bilateral-chemantr?noredirect=1#comment130131_40189):
>[(Wikipedia) says](https://en.wikipedia.org/wiki/Bond-dissociation_... |
Thermal decomposition of steam to hydrogen and oxygen; at what temperature is half decomposed and how to calculate? |
To dissolve branded food from e. g. a baking tray, there is the advice to pour table salt on it and heat it up in a baking oven or on a hotplate until the salt turns brown. From practice I confirm that it works.
But I'd like to know why it works. Can somebody please explain it in layman's terms (my chemistry knowledge... |
In comments below [this answer](https://space.stackexchange.com/q/40189/12102) in Space Exploration SE [I've said](https://space.stackexchange.com/questions/40189/lantr-has-been-proposed-why-not-bilateral-chemantr?noredirect=1#comment130131_40189):
>[(Wikipedia) says](https://en.wikipedia.org/wiki/Bond-dissociation_... |
Can coal (carbon) be "burned" in a hydrogen atmosphere? I know it would not match the definition of "combustion".
But is the reaction $$\ce{C +2H2 ->CH4}$$ exothermic?
(I'm fairly convinced this is a duplicate, but I didn't find any question like that.) |
So I'm trying to use the LCAO method to calculate molecular orbitals on a square lattice of hydrogen atoms. To this end, I need to compute the Hamiltonian matrix. With the nearest neighbor interaction approximation, the matrix should be pentadiagonal, analogous to the Laplacian matrix.
Now the problem is that I don't ... |
So I'm trying to use the LCAO method to calculate molecular orbitals on a square lattice of hydrogen atoms. To this end, I need to compute the Hamiltonian matrix. With the nearest neighbor interaction approximation, the matrix should be pentadiagonal, analogous to the Laplacian matrix.
Now the problem is that I don't ... |
So I'm trying to use the LCAO method to calculate molecular orbitals on a square lattice of hydrogen atoms. To this end, I need to compute the Hamiltonian matrix. With the nearest neighbor interaction approximation, the matrix should be pentadiagonal, analogous to the Laplacian matrix.
Now the problem is that I don't ... |
To dissolve branded food from e. g. a baking tray, there is the advice to pour table salt on it and heat it up in a baking oven or on a hotplate until the salt turns brown. From practice I confirm that it works.
But I'd like to know why it works. Can somebody please explain it in layman's terms (my chemistry knowledge... |
So I'm trying to use the LCAO method to calculate molecular orbitals on a square lattice of hydrogen atoms. To this end, I need to compute the Hamiltonian matrix. With the nearest neighbor interaction approximation, the matrix should be pentadiagonal, analogous to the Laplacian matrix.
Now the problem is that I don'... |
So I'm trying to use the LCAO method to calculate molecular orbitals on a square lattice of hydrogen atoms. To this end, I need to compute the Hamiltonian matrix. With the nearest neighbor interaction approximation, the matrix should be pentadiagonal, analogous to the Laplacian matrix.
Now the problem is that I don'... |
in my book i found the following reaction
Ca(HCO3)2 -heated-> CaCO3 + ...
Mg(HCO3)2 -heated-> Mg(OH)2 +...
what makes these two reactants different? why is one forming hydroxide while the other carbonate?
|
Does magnesium carbonate exist? what makes magnesium bicarbonate different from calcium bicarbonate |
I have to identify delocalized electron pairs in Isoniazid (pairs not shown in the image below):
[![][1]][1]
I know the nitrogen in the ring has a localized electron pair, since it already forms a pi bond. I'm confused about the other two nitrogen atoms. When we draw one of the resonance structures, we can see ... |
I have to identify delocalized electron pairs in Isoniazid (pairs not shown in the image below):
[![][1]][1]
I know the nitrogen in the ring has a localized electron pair, since it already forms a pi bond. I'm confused about the other two nitrogen atoms. When we draw one of the resonance structures, we can see ... |
In my book, I found the following reactions:
$\ce{Ca(HCO3)2 ->[\Delta] CaCO3 + … }$
$\ce{Mg(HCO3)2 ->[\Delta] Mg(OH)2 +...}$
What makes these two reactants different? Why is one forming hydroxide while the other carbonate? |
Why the degree of dissociation of weak electrolyte is 1 at infinite dilution and how do we get the result? Like I know that at infinite dilution the concentration of solution is 0 but what does that have to do with degree of dissociation, secondly in oswald's law of dilution we already assume that dissociation is almos... |
I have a question regarding the use of NaCl as a water softener.
Recently i was asked to comment on a series of test results from a water softening device were a lot of corrosion had occurred post softening. Just to be sure we are on the same page, NaCl was added to the water to dissolve* the CaCO3, Ca(CO3)2 & CaSO4... |
I am attempting to perform a Fisher Esterification of 3-butenoic acid (vinyl acetic acid). I believe that this should theoretically work and not disturb the unsaturated region of the molecule, but I'm not certain. Has anyone seen any literature referencing a Fischer esterification being performed on an unsaturated acid... |
It is stated that mercury is a liquid at STP because the high relativistic mass of its valence electrons stabilizes their orbits and thus prevents the electrons from being shared. If so, liquid mercury would seem to have no "free" electrons; how, then, does it conduct electricity? |
How does liquid mercury conduct electricity? |
I know that, although many elementary books say that d-orbitals are involved in the bonding of hypervalent main group compounds period 3 or higher such as the sulfate ion but in reality they are only barely, if at all, involved in bonding.
The question is- is it true that "the d-orbitals are not directly involved in ... |
I know that, although many elementary books say that d-orbitals are involved in the bonding of hypervalent main group compounds period 3 or higher such as the sulfate ion but in reality they are only barely, if at all, involved in bonding.
The question is- is it true that "the d-orbitals are not directly involved in ... |
I am attempting to perform a Fisher esterification of 3-butenoic acid (vinyl acetic acid). I believe that this should theoretically work and not disturb the unsaturated region of the molecule, but I'm not certain. Has anyone seen any literature referencing a Fischer esterification being performed on an unsaturated acid... |
I am attempting to perform a Fisher esterification of 3-butenoic acid (vinyl acetic acid). I believe that this should theoretically work and not disturb the unsaturated region of the molecule, but I'm not certain. Has anyone seen any literature referencing a Fischer esterification being performed on an unsaturated acid... |
I know that the following substitution reaction can take place:
$\ce{[Cu(H2O)4]^2+ (aq) + 4NH3 (aq) -> [Cu(NH3)4]^2+ (aq) + 4H2O (l)}$
This is because ammonia is a stronger ligand than water.
What can we say about the product formed from the following reaction ?
$\ce{[Cu(NH3)4]^2+ (aq) + excess HNO3 (aq) ->... |
I'm working on a project to make a cup that can holds hot/cold water inside but can be dissolved from the outside. I'm just wondering if that would be possible scientifically?? |
Is it possible to put wax or PE or any kind of insoluble coating on soluble material (e.g. edible film)? |
I saw somewhere that, "in PF5, the 3d orbitals of phosphorus end up in the anti-bonding molecular orbitals, and thus contribute less to the final molecule" and that "the hypervalency of some hypervalent molecules can be explained more efficiently by canonical forms involving ionic bonds, and some by involving d-orbital... |
“*Analyte*” is the term that is usually universally understood and is listed in [IUPAC Gold Book](https://goldbook.iupac.org/terms/view/A00331):
> **analyte** The component of a system to be analysed.
However, recently I stumbled upon the word “*analy**a**te*”.
Initially I thought of it being a typo or an erron... |
“*Analyte*” is the term that is usually universally understood and is listed in [IUPAC Gold Book](https://goldbook.iupac.org/terms/view/A00331):
> **analyte** The component of a system to be analysed.
However, recently I stumbled upon the word “*analy**a**te*”.
Initially I thought of it being a typo or an erron... |
For some reason, I'm reviewing General chemistry, and I find that the elementary reaction for the RDS is assumed to be irreversible, that is, single arrow, in all questions that I see.
For example, Think a reaction consisting of two elementary reactions:
$$
A + B \:\:\xrightleftharpoons[k_{1}']{k_{1}}\:\:\: C \:(... |
I remember my grandmother putting lots of kersoene on my wound when i was kid and got a huge cut on my finger, as there was no health facility around.
Want to confirm if chemist do agree on antisecptics role of kerosene, or grandma was just using useless remedy? |
I remember my grandmother putting lots of kerosene on my wound when I was kid and got a huge cut on my finger, as there was no health facility around.
Want to confirm if chemists do agree on antiseptics role of kerosene, or grandma was just using useless remedy? |
For some reason, I am reviewing general chemistry and I find that the elementary reaction for the rate-determining step (RDS) is assumed to be irreversible, that is, single arrow, in all questions that I see.
For example, think a reaction consisting of two elementary reactions:
$$\ce{A + B <=>[$k_1$][$k_1^\prime... |
For some reason, I am reviewing general chemistry and I find that the elementary reaction for the rate-determining step (RDS) is assumed to be irreversible, that is, single arrow, in all questions that I see.
For example, think a reaction consisting of two elementary reactions:
$$\ce{A + B <=>[$k_1$][$k_1^\prime... |
Let me split the question in to and address the parts separately.
1. Are *d*-orbitals essecial to describe bonding in 3+ periods?
If we are talking about practical calculations, than yes, absolutely. d-Type basis function are a vital correction to p-orbitals. For $\ce{PF5}$ population analysis shows considerable ... |
In comments below [this answer](https://space.stackexchange.com/q/40189/12102) in Space Exploration SE [I've said](https://space.stackexchange.com/questions/40189/lantr-has-been-proposed-why-not-bilateral-chemantr?noredirect=1#comment130131_40189):
>[(Wikipedia) says](https://en.wikipedia.org/wiki/Bond-dissociation_... |
For some reason, I am reviewing general chemistry and I find that the elementary reaction for the rate-determining step (RDS) is assumed to be irreversible, that is, single arrow, in all questions that I see.
For example, think a reaction consisting of two elementary reactions:
$$\ce{A + B <=>[k_1][k_1^\prime] C... |
> Thus, the rate is
$$
\mathrm{rate} = k_{2}[\mathrm{C}] - k_{2}'[\mathrm{D}].
$$
Though, I'm not sure if the reasoning is right. Is it correct?
This is correct but does not give you much insight into how [D] changes over time. This system will reach equilibrium eventually. If you call the equilibrium constants ... |
> Thus, the rate is
$$
\mathrm{rate} = k_{2}[\mathrm{C}] - k{_2}'[\mathrm{D}].
$$
Though, I'm not sure if the reasoning is right. Is it correct?
This is correct but does not give you much insight into how [D] changes over time. This system will reach equilibrium eventually. If you call the equilibrium concentrat... |
Let me split the question in two and address the parts separately.
1. Are *d*-orbitals essecial to describe bonding in 3+ periods?
If we are talking about practical calculations, than yes, absolutely. d-Type basis function are a vital correction to p-orbitals. For $\ce{PF5}$ population analysis shows considerable... |
> Thus, the rate is
$$
\mathrm{rate} = k_{2}[\mathrm{C}] - k{_2}'[\mathrm{D}].
$$
Though, I'm not sure if the reasoning is right. Is it correct?
This is correct but does not give you much insight into how [D] changes over time. This system will reach equilibrium eventually. If you call the equilibrium concentrat... |
I have been learning about SP3 hybridisation and slightly confused why it it results in 4 sp3 orbitals.
My understanding is this...
The S orbital is spherical and uniform whilst the p orbitals are made of 2 lobes.
There are 3 p orbitals Px Py and Pz.
So if each of these p orbitals combines respectively with... |
> Thus, the rate is
$$
\mathrm{rate} = k_{2}[\mathrm{C}] - k{_2}'[\mathrm{D}].
$$
Though, I'm not sure if the reasoning is right. Is it correct?
This is correct but does not give you much insight into how [D] changes over time. This system will reach equilibrium eventually. If you call the equilibrium concentrat... |
What is wrong in this argument that dG must always be zero? |
While studying alkanes I came across the nitration of alkanes using Nitric acid at very high temperature, which apparently follows "free radical" mechanisms, by formation of OH° °NO2 free radical ! How homolytic cleavage of N-OH (a polar bond) is possible at any temperature ? |
Why homolytic fission of polar molecules is possible at higher temperature? |
I am performing coprecipitation reaction, and in the precipitating step, I have a bunch of metal nitrates(ferric nitrate, aluminium nitrate and barium nitrate)in a solution reacting with ammonium bicarbonate.
I need to know the selectivity of these metal nitrates towards the ammonium carbonate and the order in whi... |
Let me take two parts from the question I can address of the bat
1. Are *d*-orbitals essecial to describe bonding in 3+ periods?
If we are talking about practical calculations, than yes, absolutely. d-Type basis function are a vital correction to p-orbitals. For $\ce{PF5}$ population analysis shows considerable p... |
While studying alkanes I came across the nitration of alkanes using Nitric acid at very high temperature, which apparently follows "free radical" mechanisms, by formation of OH° °NO2 free radical ! How "homolytic" cleavage of N-OH (a polar bond) is possible at any temperature instead of heterolytic cleavage i.e forma... |
Why doesn't $\ce{H3CO3+}$ ion exist and why doesn't the carbonyl group in carbonic acid $(\ce{H2CO3})$ seem reactive? |
Does H3CO3+ ion exist and what is its structure? |
(1) $\ce{PH3(g) <=>[W]PH3(adsorption)->[W]P(s) + 3/2 H2(g)}$
The **decomposition** of phosphine on tungsten surface at low pressure is a pseudo first order reaction. This is because the rate of the reaction depends on the partial pressure of phosphine and which depends on the surface area of tungsten covered by phos... |
It's well known that activated charcoal is an adsorbent and due to very big surface area per unit of mass it can adsorb a lot of particles.
Let's take as an example for my question [this product](https://www.amazon.com/dp/B01N7NHVZK/) on Amazon.
My questions are the followings:
1. How much do this apply to th... |
Is activated charcoal an air purrifier? |
R. M.'s answer is incorrect. The flammability of an oxygen-nitrogen mixture is much more dependent on oxygen concentration than on oxygen partial pressure. See "Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?", Journal of ASTM International, 2016. |
1. Agreed: unless air is pushed through the activated charcoal bed, few impurities would be adsorbed.
2. It would depend on how tightly the substance clings to the carbon, i.e. it would vary with impurity, but [Trox Technik KS Filters recommends,][1] "saturated activated carbon is reprocessed... with a gradual increa... |
1. Agreed: unless air is pushed through the activated charcoal bed, few impurities would be adsorbed.
2. It would depend on how tightly the substance clings to the carbon, i.e. it would vary with impurity, but [Trox Technik KS Filters recommends,][1] "saturated activated carbon is reprocessed... with a gradual increa... |
What can I mix with hand sanitizer to make it heat up as I apply to/rub into my hands? Something that doesn't affect the sanitizing. |
Wikipedia says that lithium tetrafluoroborate decomposes to lithium fluoride and boron trifluoride when heated. Does the same hold for sodium tetrachloroaluminate (all anhydrous) as well? |
Is the pyrolysis of tetrachloroaluminate(1-) anion possible? |
How do Lewis Acids interact with 1,4 diketones and amines to form an alkaloid? |
[![Two forms of intramolecular hydrogen bonding in Salicylic acid][1]][1]
[1]: https://i.stack.imgur.com/38RGb.png
When I googled about intramolecular hydrogen bonding in Salicylic acid, I found that there are two type of hydrogen bonding. Which one is more appropriate?
And another question, if there ARE ... |
which oxygen atom make intramolecular hydrogen bond in salicyclic acid? |
> Which system at equilibrium will not be influenced by a change in pressure?
> $$
\begin{align}
\ce{3 O2(g) &<=> 2 O3(g)}\tag{A}\\
\ce{N2(g) + 3 H2(g) &<=> 2 NH3(g)}\tag{B}\\
\ce{2 NO2(g) &<=> N2O4(g)}\tag{C}\\
\ce{H2(g) + I2(g) &<=> 2 HI(g)}\tag{D}\\
\ce{2 W(g) + X(g) &<=> 3 Y(g) + 2 Z(s)}\tag{E}
\end{align... |
I was wondering what would be the most stable physiological buffer for nicotinamide adenine dinucleotide (NAD+), for potential storage as frozen aliquots - 6 months stability or around there would be ideal. A buffer that is physiologically compatible is essential (e.g. suitable for *in vivo* use).
I would also be in... |
I have a mixture of $\mathrm{NO_{2(g)}}$ and $\mathrm{N_2O_{4(g)}}$ at $63\,\mathrm{C^°}$ and $750\,\mathrm{mmHg}$. I need to find the weight percent of the first compound.
I assumed that we have $M=aM_1+bM_2$ where $M_1$ and $M_2$ are the molar masses of the first and second compound. I know that $m=nM$ so the weig... |
[Wikipedia](https://en.wikipedia.org/wiki/Lithium_tetrafluoroborate) says that lithium tetrafluoroborate decomposes to lithium fluoride and boron trifluoride when heated. Does the same hold for sodium tetrachloroaluminate (all anhydrous) as well? |
Is the pyrolysis of tetrachloroaluminate(1−) anion possible? |
How do Lewis acids interact with 1,4-diketones and amines to form an alkaloid? |
I have a mixture of $\mathrm{NO_{2(g)}}$ and $\mathrm{N_2O_{4(g)}}$ at $63\,\mathrm{C^°}$ and $750\,\mathrm{mmHg}$. I need to find the weight percent of the first compound. Density $d=1.98\,g/L$.
I assumed that we have $M=aM_1+bM_2$ where $M_1$ and $M_2$ are the molar masses of the first and second compound. I know ... |
Does anyone know how to remove the odour remaining from a decomposed corpse which has fallen onto a wooden floor? Aparently the two main chemicals are putrescine (tetramethylenediamine) and cadaverine (pentamethylenediamine). |
I know that the following substitution reaction can take place:
$$\ce{[Cu(H2O)4]^2+ (aq) + 4NH3 (aq) -> [Cu(NH3)4]^2+ (aq) + 4H2O (l)}$$
This is because ammonia is a stronger ligand than water.
What can we say about the product formed from the following reaction?
$$\ce{[Cu(NH3)4]^2+ (aq) + excess HNO3 (aq) ... |
**Reversible reaction**
According to Merriam Webster:
>a reaction that takes place in either direction according to conditions (as the formation of hydriodic acid by union of hydrogen and iodine or its decomposition into these elements)
For this type of reaction, you would use a double-harpoon to write the che... |
Let's suppose we want to titrate a solution containing an unknown monoprotic and weak acid. We use a strong base, such as $NaOH$. When the number (and moles) of hydroxide ions is equal to the amount of hydronium ions, here we have the equivalence point. When titrating a strong monoprotic acid the equivalence points coi... |
**Reversible reaction**
According to Merriam Webster, a reversible reaction is:
>a reaction that takes place in either direction according to conditions (as the formation of hydriodic acid by union of hydrogen and iodine or its decomposition into these elements)
For this type of reaction, you would use a doubl... |
> It is generally said that reactants react so that they can achieve a lower energy state.
Here is a slightly more accurate statement: In the absence of non-PV work, the system (closed, at constant pressure) will achieve lower Gibbs energy when a reaction occurs. The less convoluted way of saying this is the second ... |
So regarding the chemiluminescence in a glow stick reaction, the glow is due to the unstable compound 1,2-dioxetanedione decomposing into carbon dioxide, releasing energy which is then absorbed by the electrons in the molecules of the dye. This promotes the electron to an ‘excited state’ and when the electrons fall bac... |
How will the degree of conjugation effect the light emitted? (glow stick reaction) |
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