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Context:
In the process of trying to calibrate a number of hygrometers, I came across the method of using wet salt in an airtight container: over time, with a given salt and at a given temperature, the relative humidity in the container will stabilize at a predictable percentage.
For a list of salts and their RH ... |
> What would be the order of $\mathrm{p}K_\mathrm{a}$ values of the following:
>
> - $\ce{O2N-CH2-CO2H},$
> - $\ce{Me3\overset{+}{N}-CH2-CO2H},$
> - $\ce{NC-CH2-CO2H},$
> - $\ce{HO-CH2-CO2H}?$
Since only the groups attached to $\ce{-CH2-CO2H}$ are changing, we must look at the point of difference in each grou... |
I'm a high school student researching the conductivity of electrolyte solutions. In [this excerpt][1] of the CRC Handbook, I noticed that different ions containing chlorine have different limiting molar conductivity, and there seems to be a trend between molar conductivity and the oxidation state of chlorine:
| Ion ... |
Is the electric conductivity of chlorine ions influenced by its oxidation state? |
If we consider an equilibrium between metal electrode and its ions in solution we know that equilibrium potential is proportional to activity of ions in solution from Nernst equation. Since this dependence is logarithmic, what we conclude is that when activity of ions tends towards zero, potential tends to minus infini... |
If we put an metal electrode in water with no metal ions present potential should tend to minus infinity? |
Why is the dihedral angle of solid hydrogen peroxide less than that of gaseous? |
<b>Q.1: How and why does Onchidal act as an AChE inhibitor? </b><br>
Onchidal is an antipredatory, feeding deterrent product secreted by marine organisms such as <i>Onchidella binneyi</i> and <i>Elysia cripata</i>, not having the protection of an external shell and thus relying on the production of a defensive secre... |
<b>Q.1: How and why does Onchidal act as an AChE inhibitor? </b><br>
Onchidal is an antipredatory, feeding deterrent product secreted by marine organisms such as <i>Onchidella binneyi</i> and <i>Elysia cripata</i>, not having the protection of an external shell and thus relying on the production of a defensive secre... |
Context:
In the process of trying to calibrate a number of hygrometers, with Sensirion MEMS electronic sensors, I came across the method of using wet salt in an airtight container: over time, with a given salt and at a given temperature, the relative humidity in the container will stabilize at a predictable percenta... |
Context:
In the process of trying to calibrate a number of hygrometers, with Sensirion MEMS electronic sensors, I came across the method of using wet salt: an airtight container will stabilize at a predictable relative humidity over time, given a particular salt and temperature.
For a list of salts and their RH v... |
In a question, this compound was given and it was asked:
"Hydrogenation of the above compound in the presence of poisoned Palladium catalyst gives?"
[![reactant][1]][1]
When I was answering it, I thought that the Lindlar catalyst would partially reduce the alkyne to give a cis alkene which would create two com... |
Why does hydrogenation of this compound not result in a diastereomeric mixture? |
Can I use a pen engraver (the kind that's like a tattoo gun with a diamond tip) to engrave my initials on labware without compromising it? I am in a lab space with a shared acid wash, and my glassware keeps getting boosted. I'm worried about e.g. heating a beaker and having it shatter because of the propagation of micr... |
Can I engrave borosilicate glassware without compromising its structural integrity? |
Zinc's relatively higher reactivity than copper is not because its highest occupied atomic orbital is $\ce{4s^2}$ while copper's is $\ce{4s^1}$; according to that magnesium should be more reactive than sodium as the highest occupied atomic orbital is $\ce{3s^2}$ while for sodium it is $\ce{3s^1}$. Therefore, this is no... |
I've quite a small quantity of concentrated Nitric acid I had acquired like two years ago. This was given to me by a friend in a couple of Pyrex volumetric flasks with stopper and some in a borosilicate reagent bottles. The acid does look like as of now like a JW black label whiskey brown color I did say.
Is there... |
How to identify the concentration of nitric acid? |
I have quite a small quantity of concentrated nitric acid I had acquired about two years ago. This was given to me by a friend in a couple of Pyrex volumetric flasks with stopper and some in a borosilicate reagent bottles. The acid does have a whiskey brown color now.
Is there any simple method or visual cue to ide... |
I had a question and was wondering if anyone could possibly explain it to me. When comparing the orbitals 2s and 2p only in the z axis , do they have the same energy levels and size? I am not so sure just because I know they both have a quantum number of 2. Thank you in advance! |
I am very confused as to how to solve this problem:
> An oxide of scandium, with a mass of 1.423 g, is chemically reduced with H2 to give H2O and 0.929 of Sc metal. What is the formula of scandium oxide? How much water is formed?
I know that the reaction is of the form:
SxOy + H2 -> H2O + Sc
x and y are the units ... |
I read here (https://chemistry.stackexchange.com/a/34016/101483) that strongly acidic catalysts can facilitate dimerization of alkene. With catalysts on zeolite to allow only the isooctane (octane rating 100) to come out as the only product, can non-recyclable plastics be turned into useful petrochemicals.
In this p... |
A useful way to reuse non-recyclable plastics: Turn them to petrochemicals, shall we? |
> An oxide of scandium, with a mass of $\pu{1.423 g},$ is chemically reduced with $\ce{H2}$ to give $\ce{H2O}$ and $\pu{0.929 g}$ of $\ce{Sc}$ metal. What is the formula of scandium oxide? How much water is formed?
I know that the reaction is of the form:
$$\ce{Sc_xO_y + H2 -> H2O + Sc},$$
where $x$ and $y$ a... |
What is the relation of water potential with gibbs free energy? |
Why does green ferrous sulfate solution change color to yellow upon addition of hydrochloric acid? |
How to calculate molar concentration from equilibrium equations with no initial concentration given? |
# Introduction #
I have been trying to use computational software to gain more insight into how molecular orbitals are formed, as well as their shapes and sizes in accordance with Molecular Orbital Theory.
## What I know so far ##
The molecule I examined was allyl bromide.
[![allyl bromide][1]][1]What I knew *theo... |
The mathematics YouTube channel *[Numberphile](https://www.youtube.com/user/numberphile/videos)'' just published a video entitled "[All the World's Coronavirus Fits in a Coke Can](https://www.youtube.com/watch?v=LVgBjRFSMYs)" in which mathematician Kit Yates makes a [Fermi estimate](https://en.wikipedia.org/wiki/Fermi_... |
The mathematics YouTube channel *[Numberphile](https://www.youtube.com/user/numberphile/videos)* just published a video entitled "[All the World's Coronavirus Fits in a Coke Can](https://www.youtube.com/watch?v=LVgBjRFSMYs)" in which mathematician Kit Yates makes a [Fermi estimate](https://en.wikipedia.org/wiki/Fermi_p... |
is there a way to calculate enthalpy of dissolution of NaOH in small amount of water?
I know that enthalpy of dissolution of sodium hydroxide in water is –44,5 kJ/mol. However it assumes the orders of magnitude higher amount of water than NaOH. (Which is not my case.) Is there any formula which does not omit the volum... |
# Introduction #
I have been trying to use computational software to gain more insight into how molecular orbitals are formed, as well as their shapes and sizes in accordance with Molecular Orbital Theory.
## What I know so far ##
The molecule I examined was allyl bromide.
[![allyl bromide][1]][1]What I knew *theo... |
Expanding a bit on the last paragraph of [Jan's answer][1]:
> The best explanation I have for the colourlessness of magnesium and beryllium is that their excitations are too close to ultraviolet to be properly observed due to strong contractions of the orbitals, but without numbers that is a weak explanation at best... |
When comparing the orbitals 2s and 2p only in the z axis, do they have the same energy levels and size? I am not so sure just because I know they both have a quantum number of 2. Thank you in advance! |
It looks like you have about 40 mL of the solution. You could measure the density by using a small volumetric flask (10 or 25 mL), or even a graduated cylinder (which you could calibrate with water). Add your solution to the mark, weigh reasonably accurately, and you will have your answer (which I predict will lie *bet... |
to evaluate the error source of my MD simulation which is only based on the Lennard Jones interaction between noble gases (Helium in this case) I wanted to ask which magnitude I have to expect for the force.
For reference: Im using ε = 1.49e-22 (in J) and σ = 2.967e-10 (in m).
The equation I'm using to calculate ... |
In my workplace we are purchasing "Nonylphenol 10 mole" and "Nonylphenol 30 mole" for use as non-ionic surfactants.
At first I assumed, because of the name, that the substance was simply nonylphenol. But further research shows that commercial non-ionic surfactants are actually ethoxylates of nonylphenol. Thus, I'm a... |
The spectrochemical series is usually known as the "strength" of the ligands. It makes sense on a basic level as the more willing a ligand is to donating its electrons (via a $\sigma$-bond), the greater the repulsion on the metal's $d$-orbitals. However, I recently learned about $\pi$-donors and $\pi$-acceptors and how... |
The intent is to evaluate the error source of a Molecular Dynamics (MD) simulation which is only based on the Lennard Jones interaction between noble gases (Helium in this case). What is the magnitude of the force?
For reference: $\pu{\epsilon = 1.49\times 10^{-22} J}$ and $\pu{\sigma = 2.967\times 10^{-10} m}$.
... |
I read here (https://chemistry.stackexchange.com/a/34016/101483) that strongly acidic catalysts can facilitate dimerization of alkene. With catalysts on zeolite to allow only the isooctane (octane rating 100) to come out as the only product, can non-recyclable plastics be turned into useful petrochemicals.
In this p... |
I am recently taking courses in environmental chemistry and I was introduced to Pourbaix diagram. I was taught that the lines in the Pourbaix diagrams are equilibrium lines. Lets take as an example the Pourbaix diagram of the water (diagram is taken from [Ibanez][1]):
&nbs... |
In electrolysis, does voltage or amperage produce more gas? |
Suppose we have the reaction :
$$\ce{A(s) + B(s) <=> C(g)}$$
The equilibrium constant will be equal to $e^{-\frac{Δ_rG}{RT}}$ and it varies with temperature. Suppose that $\ce{A}$ and $\ce{B}$ come into contact at temperature $T$ and pressure $p$ where the phase diagram for $\ce{C}$ at these conditions correspond... |
Can a reaction happen if a product change phase under reaction conditions? |
Full Question: You are asked to prepare 2.0 L of a HCN/NaCN buffer that has a pH of 9.8 and an osmotic pressure of 1.35 atm at 298 K. What masses of HCN and NaCN should you use to prepare the buffer? (Assume complete dissociation of NaCN.)
**Here is my work for the problem:**
**pH=-log(Ka)+log([CN-]/[HCN])**
9... |
I read here (https://chemistry.stackexchange.com/a/34016/101483) that strongly acidic catalysts can facilitate dimerization of alkene. With catalysts on zeolite to allow only the isooctane (octane rating 100) to come out as the only product, can non-recyclable plastics be turned into useful petrochemicals.
In this p... |
Nonylphenols are a family of closely related organic compounds composed of phenol bearing a 9 carbon-tail ([Wikipedia](https://en.wikipedia.org/wiki/Nonylphenol)). Following is an example of nonylphenols:
[![Example of Nonylphenols][1]][1]
However, "Nonylphenol $n$ mole" is a commercial name for non-ionic surfa... |
Suppose we have the reaction :
$$\ce{A(s) + B(s) <=> C(g)}$$
The equilibrium constant will be equal to $e^{-\frac{Δ_rG}{RT}}$ and it varies with temperature. Suppose that $\ce{A}$ and $\ce{B}$ come into contact at temperature $T$ and pressure $p$ where the phase diagram for $\ce{C}$ at these conditions correspond... |
You are asked to prepare $\pu{2.0 L}$ of a $\ce{HCN/NaCN}$ buffer that has a $\mathrm{pH}$ of $9.8$ and an osmotic pressure of $\pu{1.35 atm}$ at $\pu{298 K}$. What masses of $\ce{HCN}$ and $\ce{NaCN}$ should you use to prepare the buffer? (Assume complete dissociation of $\ce{NaCN}$)
**Here is my work for the probl... |
I was wondering if anyone has some experience regarding my question. The geochemical simulation of mixing a mole of pyrite with a kilogram of acidic solution (pH=1) shows that Pyrite almost remains intact (PHREEQC). Do lab observations confirm this? |
Does Pyrite react with HCl? |
Rare Earth's up to z=62 (Samarium) are often called 'light' rare Earths, while z=63 (Europium) and beyond are sometimes referred to as 'heavy' ones...
Why the distinction, though?
Never have I come across (or heard about) a reason for ?arbitrarily? dividing them this way....
Are the light ones often found sepa... |
Why are the rare Earth elements divided into light and heavy categories? |
How would you recrystallize acetanilide using ethanol and hexanes? I know this compound is not soluable with the hexanes solvent. But, where would I include ethanol in the procedure? Would I heat up the ethanol and then add hexnes dropwise? |
Best solvent for recrystallization of acetanilide? |
The wiki page on vacancy defects says;
> It is also known as a Schottky defect, although in ionic crystals the concepts are not identical.
As far as I'm aware, they're the same. Furthermore, the wiki page for Schottky defects contains the term 'vacancies' while describing the phenomenon, which is linked back to t... |
For example in the following compounds
1. CoCl<sub>3</sub>.6H<sub>2</sub>O
2. CoCl<sub>3</sub>.6NH<sub>3</sub>
3. CoCl<sub>3</sub>.5NH<sub>3</sub>
4. CoCl<sub>3</sub>.4NH<sub>3</sub>
in all of these complexes we took the
a)oxidation state of Cobalt as +3 ( since there are 3 Cl<sup>-</sup> ions and N... |
Is the Co-ordination number of Cobalt always 6 in every co-ordination compound? |
For example in the following compounds
1. CoCl<sub>3</sub>.6H<sub>2</sub>O
2. CoCl<sub>3</sub>.6NH<sub>3</sub>
3. CoCl<sub>3</sub>.5NH<sub>3</sub>
4. CoCl<sub>3</sub>.4NH<sub>3</sub>
in all of these complexes, we took the
a)oxidation state of Cobalt as +3 ( since there are 3 Cl<sup>-</sup> ions and ... |
For example in the following compounds
1. CoCl<sub>3</sub>.6H<sub>2</sub>O
2. CoCl<sub>3</sub>.6NH<sub>3</sub>
3. CoCl<sub>3</sub>.5NH<sub>3</sub>
4. CoCl<sub>3</sub>.4NH<sub>3</sub>
in all of these complexes, we took the
a)oxidation state of Cobalt as +3 ( since there are 3 Cl<sup>-</sup> ions and ... |
How would you recrystallize acetanilide using ethanol and hexanes? I know this compound is not soluble with the hexanes solvent. But, where would I include ethanol in the procedure? Would I heat up the ethanol and then add hexanes dropwise? |
Is there any logical way to determine whether I- will oxidise to form I2 or IO3- is a reaction ?
For example,<br>
In reaction of KMnO4 with I- in acidic medium I2 wil be formed,<br>
whereas in the reaction of KMnO4 with I- in alkaline medium IO3- would be formed.<br>
HNO3 will oxidise I2 to IO3-
Is it rel... |
I had a doubt while reading about the saponification reaction of esters in basic medium. What is the molecularity of the reaction and why? <br />
P.S - I think its bimolecular and heres why - <br />
The RDS of the reaction is the formation of the tetrahedral intermediate after the attack of the OH ion. In this s... |
Normally, I think about orbitals interacting in the context of bonding. When two atomic orbitals overlap, they can do so in-phase or out-of-phase. The in-phase overlap results in a bonding molecular orbital with lower energy than the original AOs; conversely, the out-of-phase overlap results in an antibonding MO with h... |
Why are steric effects repulsive? |
The intent is to evaluate the error source of a molecular dynamics (MD) simulation which is only based on the Lennard-Jones interaction between noble gases (helium in this case). What is the magnitude of the force?
For reference: $\varepsilon = \pu{1.49E-22 J}$ and $\sigma = \pu{2.967E-10 m}.$
The equation used to ... |
I was reading the properties of Chlorine when I came across this statement:
> Chlorine is a powerful bleaching agent; bleaching action is due to oxidation. Chlorine bleaches vegetable or organic matter in the presence of moisture. *Bleaching effect of chlorine is permanent.* $$ \ce { Cl_2 +H_2O -> 2HCl + O} $$ $$ \c... |
Why is bleaching with Chlorine permanent but with Sulphur Dioxide temporary? |
I have a brief doubt and maybe someone around here can give as some help. We are doing a pilot study on microplastics using a fluorescence method (red nile). The dye is solvachromic, so it's emission spectrum changes by the polarity of the media. We do have the spectra for the excitation (mostly blue light) and emissio... |
What exactly is the significance of molar mass in chemistry? Why not just mass? |
Is there any logical way to determine whether $\ce{I-}$ will oxidize to form $\ce{I2}$ or $\ce{IO3-}$ is a reaction ?
For example,<br>
In reaction of $\ce{KMnO4}$ with $\ce{I-}$ in acidic medium $\ce{I2}$ will be formed,
whereas in the reaction of $\ce{KMnO4}$ with $\ce{I-}$ in alkaline medium $\ce{IO3-}$ would b... |
**_tl;dr_–** It's just normal addition. Chemical species are basically just vectors of periodic-table-elements (and similar things). Multiplication/division gets involved when we're talking about the odds of a component being present at a reaction-site, which is multiplicative as that's how statistics works.
... |
**_tl;dr_–** It's just normal addition. Chemical species are basically just vectors of periodic-table-elements (and similar things). Multiplication/division gets involved when we're talking about the odds of a component being present at a reaction-site, which is multiplicative as that's how statistics works.
... |
**_tl;dr_–** It's just normal addition. Chemical species are basically just vectors of periodic-table-elements (and similar things). Multiplication/division gets involved when we're talking about the odds of a component being present at a reaction-site, which is multiplicative as that's how statistics works.
... |
The intent is to evaluate the error source of a molecular dynamics (MD) simulation which is only based on the Lennard-Jones interaction between noble gases (helium in this case). What is the magnitude of the force?
For reference: $\varepsilon = \pu{1.49E-22 J}$ and $\sigma = \pu{2.967E-10 m}.$
The equation used to ... |
**_tl;dr_–** It's just normal addition. Chemical species are basically just vectors of periodic-table-elements (and similar things). Multiplication/division gets involved when we're talking about the odds of a component being present at a reaction-site, which is multiplicative as that's how statistics works.
... |
I previously learned in books that in reversed phase chromatography, retention time changes depending on the content in mobile phase. As the polarity of mobile phase increases, retention time decreases. Can somebody explain why? |
This is what I found on wiki:
> In chemistry, a racemic mixture, is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule.
> Homochirality can also refer to enantiopure substances in which all the constituents are the same enantiomer ...
But what is the term for a collection of ch... |
What is term for a collection of chiral molecules of unequal amounts of left- and right-handed enantiomers? |
**_tl;dr_–** It's just normal addition. Chemical species are basically just vectors of periodic-table-elements (and similar things). Multiplication/division gets involved when we're talking about the odds of a component being present at a reaction-site, which is multiplicative as that's how statistics works.
... |
I previously learned in books that in reversed phase chromatography, retention time changes depending on the content in mobile phase, which means as the polarity of mobile phase increases, retention time decreases. For example, let's say there are two kinds of combination of water and methanol(5:5 and 6:4 ratio). The l... |
While studying the variational principle in McQuarrie's Quantum Chemistry, I came across the following problem: to relate the difference between an approximation $\phi$ and the exact ground-state wave function $\psi_0$ with the difference between the approximate energy $E=\int\phi^* \hat H \phi \, \text{d} \tau$ and th... |
Is it true that the better the trial function, the better approximation for the energy in variational principle? |
What is the term for a collection of chiral molecules of unequal amounts of left- and right-handed enantiomers? |
You are thinking just the opposite. RPLC is usually done for hydrophobic compounds. C18 columns do not retain hydrophilic compounds; say uracil or cytosine will not show much retention.
Suppose you have a hydrophobic compound such as naphthalene and do RPLC using 50:50 Water: Methanol and 60:40 Water: Methanol. Whi... |
It is well known that EDTA can be used for titrations involving complexations of highly charged metal cations, with the most well known being those of the alkali earth metals and transition metals. However, would it be possible to analyze metal cations such as the alkali metals or singly charged transition metals? |
What is the explanation for the two possible reactions of $\ce{H2O2}$ with $\ce{KI}$ in acid media (iodide-catalyzed decomposition of hydrogen peroxide or iodide oxidation by hydrogen peroxide) and what determines the prevalence of one over the other?
It is known that if the hydrogen peroxide is concentrated, the pa... |
I was reading the properties of chlorine when I came across this statement:
> Chlorine is a powerful bleaching agent; bleaching action is due to oxidation. Chlorine bleaches vegetable or organic matter in the presence of moisture. *Bleaching effect of chlorine is permanent.* $$ \ce { Cl_2 +H_2O -> 2HCl + O} $$ $$ \c... |
Why is bleaching with chlorine permanent but with sulphur dioxide temporary? |
In many of the precious metal refining videos Cody (Cody's Lab) takes the sample with the precious metal and puts Litharge into it. After heating it in the furnace, while pouring it out the molten lead comes out and Cody says that the precious metal is all inside the molten lead(Later extracting it using cupellation). ... |
Why does Cody use Litharge? |
In many of the precious metal refining videos Cody (Cody's Lab) takes the sample with the precious metal and puts Litharge into it. After heating it in the furnace, while pouring it out the molten lead comes out and Cody says that the precious metal is all inside the molten lead(Later extracting it using cupellation). ... |
According to literature, dimethyl paraoxon has a reaction rate constant for the aging (Spontaneous dealkylation) of acetylcholinesterase of 0.186/hr, a spontaneous reactivation rate constant of 1.01/hr, and an inhibition reaction rate constant of 1.2 × (10^6)/Mmin, compared to 0.022/hr, 0.022/hr, and 2.2 × (10^6)/Mmin ... |
I think the abstract of the reference did not give away what's going on the reaction. However, I assume that the full paper should have described what's happening to at least certain extend. Since I don't have access to this paper at the moment, only I can do is speculate. Yet, I'd direct you to reliable [source](http:... |
My lecturer has told me that water, having a high dielectric value, will "shield" ions and reduce ion-ion attractions.
[![enter image description here][1]][1]
I really don't see why. Having water molecules surround these two ions doesn't mean that Coloumb's force doesn't exist anymore - nothing in $F=\frac{kQq}{r... |
Why does water weaken ion ion attractions? |
I think the abstract of the reference did not give away what's going on the reaction. However, I assume that the full paper should have described what's happening to at least certain extend. Since I don't have access to this paper at the moment, only I can do is speculate. Yet, I'd direct you to reliable [source](http:... |
My lecturer has told me that water, having a high dielectric value, will "shield" ions and reduce ion-ion attractions.
[![enter image description here][1]][1]
I really don't see why. Having water molecules surround these two ions doesn't mean that Coloumb's force doesn't exist anymore - nothing in $F=\frac{kQq}{r... |
In many of the precious metal refining videos Cody (Cody's Lab) takes the sample with the precious metal and puts Litharge into it. After heating it in the furnace, while pouring it out the molten lead comes out and Cody says that the precious metal is all inside the molten lead(Later extracting it using cupellation). ... |
I came across three reactions while studying p-block compounds in inorganic chemistry.
**Reaction 1**- 2Al + 2NaOH + 6H\($_2$)O --> Na[Al(OH)\($_4$)] + 3H($_2$)
**Reaction 2**- Al\($_2$)O\($_3$) + 2NaOH + 3H\($_2$)O --> Na[Al(OH)\($_4$)]
**Reaction 3**- Al\($_2$)O\($_3$) + 6NaOH + 3H\($_2$)O --> Na\($_3$)[Al(... |
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