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It is mentioned in my textbook that all lipids have one common trait :they are insoluble in water;they are hydropohic.
I want to ask ,since polysaccharides are also insoluble in water,what makes them not classified within lipids? |
How are polysaccharides different from lipids? |
This question kind of borders on the fields of both semantics and math, as well as chemistry, but I still believe this is the right place to ask.
On a test I took, a question was posed as such:
>Via titration we are adding a solution of 25 ml, with 0.5 M NaOH, to 25 ml of HCl. What will the concentration of the ... |
Is this question answerable? |
Is this stoichiometric question answerable? (unknown variable) |
I am studying Magnetic Resonance Spectroscopy and I have some difficulties in understanding the j-j coupling interaction. What does actually happen from the physical point of view to the electronic cloud of the neighbouring atom? When I try to understand in books like A Complete Introduction to MODERN NMR Spctroscopy o... |
This question kind of borders on the fields of both semantics and math, as well as chemistry, but I still believe this is the right place to ask.
On a test I took, a question was posed as such:
>Via titration we are adding a solution of 25 ml, with 0.5 M NaOH, to 25 ml of HCl. What will the concentration of the ... |
I was studying for a PhD entrance exam and this question made me wonder about some topics in kinetics:
Consider the multi-step reaction below:
$\ce{A_2 → 2 A}$
$\ce{2A + X → Y + B}$
$\ce{B → A2 + Z}$
Which one can't be determined from the given equations:
**a)** The general balanced equation
*False... |
It is mentioned in my textbook that all lipids have one common trait which defines them :they are insoluble in water;they are hydropohic.
I want to ask ,since polysaccharides are also insoluble in water,what makes them not classified within lipids? |
Why polysaccharides are not considered as lipids? |
Purchasing chemicals online often I see "Sodium Deoxycholate, ≥97% (**titration**)" offers. Is there any publicly available titration protocol I can use to confirm that statement in my very basic lab which does not have HPLC? |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/Asbrw.jpg
Hey guys. I have been working on enthalpies and literally every video and website I’ve seen,
the formula for calculating enthalpy of solution = lattice enthalpy of dissociation + enthalpy of hydration, using which, I got a few ... |
Does the enthalpy of solution formula (LE + Hyd) change depending on the question? |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/Asbrw.jpg
Hey guys. I have been working on enthalpies and literally every video and website I’ve seen,
the formula for calculating enthalpy of solution = lattice enthalpy of dissociation + enthalpy of hydration, using which, I got a few ... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/Asbrw.jpg
Hey guys. I have been working on enthalpies and literally every video and website I’ve seen,
the formula for calculating enthalpy of solution = lattice enthalpy of dissociation + enthalpy of hydration, using which, I got a few ... |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
I have seen it described as soap molecules releasing energy when forming micelles. Is that correct? Is it an exothermic reaction?
I mean a bunch of molecules uniting to form a micelle. |
Is soap forming micelles in water an exothermic reaction? |
Can soap make an liposome around virsuses? |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
I'm learning about acid-base equilibria. I know that an (Bronsted-Lowry) acid donates a hydrogen proton, and a base donates a hydrogen proton, but I've also heard about a Lewis acid base theory, where electrons are the key difference. What's the point of making a even more general? And I'm not sure exactly what an salt... |
How do I tell the difference between an acid, base, and a salt solution? |
Why do nitrogen containing organic compounds give N2 as the combustion product? |
in RDKit, there is this nice [function][1] to decompose a chemical compound into its scaffolds.
Is there a way to automatically name the scaffolds?
I usually search names in PubChem but this may not be practical for a large dataaset.
[1]: https://www.rdkit.org/docs/source/rdkit.Chem.Scaffolds.MurckoScaffol... |
My teacher gave the explanation stating that consider that first the nitrogen in lower state is oxidised to $\ce{N2}$ and then the further oxidation would stop as the $\ce{N-N}$ bond energy of $\ce{N2}$ is very high and can't be overcome under normal conditions.
But my doubt is can't the nascent nitrogen (formed dur... |
Why do nitrogen-containing organic compounds give N2 as the combustion product? |
Rather, all depends on what aspects or criteria you evaluate.
- If the compound fits criteria for [salts][1], it is a salt.
- If the compound fits criteria for [acids][2], it is an acid.
- If the compound fits criteria for [bases][3], it is a base.
And the main point is - these categories are not mutuall... |
I am looking for a database containing detailed reaction mechanisms for (homogenous) catalytic reactions. Regular organic textbooks or papers generally draw some broad picture of how the mechanism may work, but generally, they skip many steps.
Is there any collection of detailed mechanisms?
I am primarily interest... |
So I stumbled on a research paper that uses mμg as a mass unit.
Here is the paper:
https://journals.sagepub.com/doi/abs/10.3181/00379727-123-31527
But I couldn't find anything about this measure unit anywhere except a recommendation not to use it.
So how much is 1 mμg?
I suppose it means milli-micro-grams so it... |
Acyclic amine in which three groups are different with a lone pair of electron is optically inactive and nitrogen is achiral because of the rapid pyramidal inversion.
[![enter image description here][1]][1]
Does similar inversion happen in ephedrine?
If yes, doesn't the inversion cancel the optical activi... |
Why is ephedrine optically active? |
Looks like in 1966 there were still residues of double prefix notation in use.
Here's an entry from Russ Rowlett's compilation of units on ibiblio.org (Rowlett):<br>
><b>millimicro- (mμ-)</b><br>
an obsolete metric prefix denoting 10<sup>-9</sup> or one billionth. This prefix has been replaced by nano- (n-).
... |
The wave function of the $2p_z$ orbital is $Ψ=1/(4√(2π))×(Z/a)^{5/2}×r×e^{-Zr/a}cosθ$.
I'm confused if this function will be a 3 dimensional function or a 4 dimensional function?
My professor told me that $z/r=cosθ$,where θ is the angle made by r with the z axis so I guess it will be 4 dimensional since we would have... |
I want to draw arrows like the one in the figure shown (with reagent *a* beside it) in ChemDraw 16.0[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/Qp2jP.png
What is the best way to go about this?
I couldn't find anything like it in the arrow options in ChemDraw Prime 16.0
Thank ... |
How to draw "box"/square arrows in Chemdraw Prime 16.0? |
In the metallurgy of $\ce{Pb}$, Galena is first concentrated by froth floatation process. It is then partially roasted to and self reduced to obtain $\ce{Pb}$.
>Why is galena only partially roasted(that is in limited oxygen supply)?
My initial thought was that sulphur could further react with $\ce{O2}$ to form $\... |
The wave function of the $2\mathrm{p}_z$ orbital is
$$Ψ = \frac{1}{4\sqrt{2π}}\left(\frac Z a\right)^{5/2} r \mathrm e^{-Zr/a}\cos θ.$$
I'm confused if this function will be a three-dimensional function or a four-dimensional function?
My professor told me that
$$z/r = \cos θ,$$
where $θ$ is the angle mad... |
Is $2\mathrm p_z$ orbital wave function three- or four-dimensional? |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
So I stumbled on a research paper by Okuda and Takedatsu \[[1](https://doi.org/10.3181/00379727-123-31527)\] that uses mμg as a symbol for the mass unit.
I couldn't find anything about this measure unit anywhere except a recommendation not to use it.
So how much is 1 mμg?
I suppose it means milli-micro-grams, so ... |
How much is 1 mμg? |
Is there any reason as to why we assume the volume of ideal gas to be negligible in comparison to the container? What is the underlying reason to assume that the ideal gas molecules are point molecules?
Why can we not assume them to be non-point particles? |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
Is the pz orbital wave function three- or four-dimensional? |
In a previous post, I was told to look into silanol activity. However, I was unable to find a textbook-style description. All the articles I've seen where silanol activity was discussed assumed it was a known prerequisite.
Could anyone explain silanol activity, or direct me to an online explanation please? |
In a previous [post][1], I was told to look into silanol activity. However, I was unable to find a textbook-style description. All the articles I've seen where silanol activity was discussed assumed it was a known prerequisite.
Could anyone explain silanol activity, or direct me to an online explanation please?
... |
**Because it gives simpler-to-derive laws which are often very good approximations**
Clearly real gases do not *always* follow the ideal gas laws. They mostly liquefy under some conditions, for example, and, under those conditions they are clearly not ideal.
But in practice gas laws are used for things far away f... |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
For example if we want to sythesize dipeptid Glu-Ala. My question is when it comes to aminoacid Glu. It has two carboxyl groups, one reacts with the amino group from the other aminoacid, but before the forming of the bond we have to "protect" the other groups that do not react. Do we need to protect also the other carb... |
It is actually the two single-paired electrons are more likely to be promoted than the two paired electrons.
Promoting the electrons always cost energy whether the electrons in question are paired or not. In the classical examples of hybridization (where they might actually promote a paired electron), this energy co... |
An oxidizing agent pulls the electron cloud of the substance being oxidized towards itself, for example:
$$\ce{F2 + 2 X- -> 2F- + X2}\qquad (\ce{X} = \ce{Cl}, \ce{Br}, \ce{I})$$
We also know that fluorine has very high charge/mass ratio as it is very small in size and its electron gain enthalpy is know to be ver... |
In a previous [post][1] about how pyridine failed to move much from the baseline of a TLC, I was told to look into "silanol activity". However, I was unable to find a textbook-style description. All the articles I've seen where silanol activity was discussed assumed it was a known prerequisite.
Could anyone explain... |
What is "silanol activity"? |
In a previous [post][1] about how pyridine failed to move much from the baseline of a TLC, I was told to look into "silanol activity". However, I was unable to find a textbook-style description. All the articles I've seen where silanol activity was discussed assumed it was a known prerequisite.
Could anyone explain... |
Consider the synthesis of the dipeptide Glu–Ala (image). The amino acid Glu (glutamic acid) has two carboxyl groups, where one of them should reacts with the amine group from the other amino acid. Does the side chain carboxyl group in Glu have to be protected also, or do we just assume that it does not react?
<img ... |
Do side chain carboxylic acids need to be protected in peptide synthesis? |
I had a hard time understanding what it means to apply a symmetry operator to a function, so I wondered if there is a formal way to define this? As far as I understand, applying a symmetry operation to a function means the following:
$$ \hat Rf(x) = f(\hat Rx) $$
The result has then to be the same function with a... |
An oxidizing agent pulls the electron cloud of the substance being oxidized towards itself, for example:
$$\ce{F2 + 2 X- -> 2F- + X2}\qquad (\ce{X} = \ce{Cl}, \ce{Br}, \ce{I})$$
We also know that fluorine has very high charge/mass ratio as it is very small in size and its electron gain enthalpy is know to be ver... |
Conducting an experiment, I found that very little salicylic acid was evolved performing hydrolysis at pH 2 and at 45 degrees C. In fact, far more salicylic acid was evolved at pH 7. This comes as a surprise to me because I expected an acid-catalyzed ester hydrolysis to actually quicken the rate of reaction and thereby... |
Conducting an experiment, I found that very little salicylic acid was evolved performing hydrolysis at pH 2 and at 45 degrees C. In fact, far more salicylic acid was evolved at pH 7. This comes as a surprise to me because I expected an acid-catalyzed ester hydrolysis to actually quicken the rate of reaction and thereby... |
I've found two methods to convert from $ppm$ to $g/m^3$. They both appear to give equivalent results, but I don't understand why. Can anyone join the dots for me and explain why they are equivalent methods, or show a derivation for Method 1? I've found a [derivation][1] for Method 2.
**Method 1 - Definition**
$$... |
Why are these two methods of converting from ppm to g/m3 equivalent? |
I am trying to understand how to account for pH-temperature relations during industrial pH measurements.
Do I have it right?:
1) The impact temperature has on the pKa of strong acids are in practical terms non existent as the equilibrium at any temperature lays very far to the right.
2) The impact of temperatu... |
there is a reaction that confused me a bit:
[![enter image description here][1]][1]
According to my research on SeCl$_4$, it can be used as a dichlorinating agent for alkenes. However, I am totally confused about the mechanism. I've read about several mechanisms using PhSeSePh as a precatalyst but in this react... |
I've learnt that water can dissolve ionic bonds , because it possess a high dielectric constant.
In the cases of covalent compounds (especially the non-polar covalent compounds), where the molecules are held together by mainly vanderwaal's forced of attraction. They are said to possess, a higher dielectric constant... |
I've learnt that water can dissolve ionic bonds , because it possess a high dielectric constant.
In the cases of covalent compounds (especially the non-polar covalent compounds), where the molecules are held together by mainly van der Waal's forced of attraction. They are said to possess, a higher dielectric consta... |
> The impact temperature has on the pKa of strong acids are in practical terms non existent as the equilibrium at any temperature lays very far to the right.
Practically, yes.
> The impact of temperature on pKa are more significant for weaker acids.
Yes.
> The impact of temperature on pKw is only... |
I am reading a book and it gives the following answer:
No, the density of water changes with
temperature. 10.0 mL of water at 10 °C would
have a higher mass than 10.0 mL of water at
25 °C because the density is higher at 10 °C.
For me it doesn't make sense. In other part of the book it states... |
Would 10.0 mL of water at 10 °C have the same mass as 10.0 mL of water at 25 °C? |
I've learnt that water can dissolve ionic bonds because it possesses a high dielectric constant.
In the cases of covalent compounds (especially the non-polar covalent compounds), where the molecules are held together by mainly van der Waals forces of attraction. They are said to possess a higher dielectric constant... |
I have noticed when I have done some combustion equilibrium that enthalpy is higher when doing a constant volume combustion than pressure constant combustion.
**Why is it so ? What are the reasons explaining that ?**
Is it because at constant pressure combustion the variation of enthalpy is equal to heat transfer... |
Why constant volume combustion gives higher energy than constant pressure? |
I am confused actually. A 10% alcoholic KOH solution means that there is 10g of KOH in 100 ml of ethanol, or 10g KOH in 100 g of ethanol or something entirely different?
Also, I understand that the solution is to be clear. I tried the 10g of KOH in 10 ml of ethanol, and somehow it is a turbid solution. Any thoughts... |
How to prepare a 10% alcoholic KOH solution? |
Why can the specific heat at constant Pressure (Cp) be used to calculate the change in enthalpy ,dh = Cp(dt) for processes that are not at constant pressure? |
I'm relatively new to Chemistry and I have a problem comprehending the following problem:
>The following reversible system is at equilibrium:
>$$\ce{P_{4(s)} + 6Cl_{2(g)} <=> 4PCl_{3(l)}} $$
>What happens with the equilibrium if $\ce{P_4}$ is added.
Normally, by applying _Le Chatelier's principle_ the equilibri... |
I'm relatively new to Chemistry and I have a problem comprehending the following problem:
>The following reversible system is at equilibrium:
>$$\ce{P_{4(s)} + 6Cl_{2(g)} <=> 4PCl_{3(l)}} $$
>What happens with the equilibrium if $\ce{P_4}$ is added.
Normally, by applying _Le Chatelier's principle_ the equilibri... |
Why can the specific heat at constant Pressure (Cp) be used to calculate the change in enthalpy ,dh = Cp(dT) for processes that are not at constant pressure?
I have dh = Cp*dT + v*dP. Why do we neglect the v*dP term? For gases, v, the specific volume, can be very large, so an increase in pressure could have a non-ne... |
I am reading a book and it gives the following answer:
> No, the density of water changes with
> temperature. 10.0 mL of water at 10 °C would
> have a higher mass than 10.0 mL of water at
> 25 °C because the density is higher at 10 °C.
For me it doesn't make sense. In other part of the book it... |
I've recently gained an interest in the whole topic of lapping and the creation of flat surfaces.
Lapping is done in different ways, but the one I'm interested in is essentially just rubbing 2 surfaces together with an abrasive in the middle. The slurry is a liquid with the very tiny abrasive particles suspended in ... |
How is lapping slurry made? |
Consider the following rxns:
1. C+O2-->CO2
2. 2C+O2-->2CO
3. 2CO+O2-->2CO2
{(2)+(3)}÷2 yields (1)
Since ∆G is a state function so why don't the straight lines corresponding these rxns in the ellingham Diagram intersect at a point? |
Marquis Reagent (1) is a spot test for alkaloids, first reported in 1896. The original agent was a mixture of 2 drops of 40% formaldehyde and 3 milliliters of concentrated sulfuric acid and was used to detect certain (e.g., opium) alkaloids and distinguish between them. The signature of the alkaloid is both the initial... |
For example, I have formic acid and sodium formate. How do I know the NIE equation is $HCHO_2 \ + \ H_2O \rightleftharpoons H_3O^+ \ + \ CHO_2^-$ and not $HCHO_2 \ + OH^- \rightleftharpoons H_2O \ + \ CHO_2^-$ ?If I told you I added $HCl$ or $NaOH$, would that help decide which one? Is a buffer always added to water? W... |
How do you determine the NIE equation of a buffer? |
I was going to start a project on Borophene, and hence I was going through a review journal, **2D Boron: Boraphene, Borophene, Boronene**, where they have said many types of borophenes had been proposed. They have been given different greek letters like α, β, γ (β12), δ and χ(chi) to classify different types and they a... |
Exactly how the subscripted numbers are given to the different types of boron sheets (borophenes)? |
For example, I have formic acid and sodium formate. How do I know the NIE(net ionic equation) equation is $HCHO_2 \ + \ H_2O \rightleftharpoons H_3O^+ \ + \ CHO_2^-$ and not $HCHO_2 \ + OH^- \rightleftharpoons H_2O \ + \ CHO_2^-$ ? If I added $HCl$ or $NaOH$, would that help decide which equation? Is a buffer always ad... |
We say that homogeneous substance consists of the chemically same type of molecules whereas heterogeneous ones vary chemically, ie the molecules throughout are not same and also not uniform.
Why do we treat a water+water vapour system as heterogeneous in spite of similar molecules present? Also if there exists an eq... |
For example, I have formic acid and sodium formate. How do I know the NIE(net ionic equation) equation is $\ce{HCHO_2 + H_2O <=> H_3O+ + CHO_2-}$ and not $\ce{HCHO_2 + OH- <=> H_2O + CHO_2-}$ ? If I added $\ce{HCl}$ or $\ce{NaOH}$, would that help decide which equation? Is a buffer always added to water? Why or why not... |
Any classification like chemical or a physical change, homogeneous or heterogeneous substance, will eventually fail at one point. From an analytical or physical chemistry's perspective, homogeneous substance is a substance, in a single phase, whose chemical composition is uniform. A heterogeneous substance has differen... |
I came across a certain line in my textbook that says:
"As the atomic number increases the energy of orbitals decreases"
Can someone please explain how this happens?
My explanation is: As number of protons increases, the increased positive charge pulls the electrons closer to the nucleus, thus reducing the siz... |
How to explain the relation between atomic number and energy of orbitals? |
[![4-bromo-1-tert-butyl-2-methylcycloheptane molecule][1]][1]
[1]: https://i.stack.imgur.com/IEzjz.jpg
I'm having a hard time understanding why the numbering for this molecule is: 4-bromo-1-tert-butyl-2-methylcycloheptane, instead of: 1-bromo-4-tert-butyl-3methylcycloheptane. Is it just because the overall numb... |
There is a reaction that confused me a bit:
[![enter image description here][1]][1]
According to my research on SeCl$_4$, it can be used as a dichlorinating agent for alkenes. However, I am totally confused about the mechanism. I've read about several mechanisms using PhSeSePh as a precatalyst, but in this reac... |
I was just searching whether Uracil is aromatic or not and in this [link](https://pubs.acs.org/doi/10.1021/jp404938u#:~:text=It%20was%20found%20that%20uracil,character%20in%20the%20gaseous%20phase.)$^1$ it is said that (from the abstract):
> High-level computational methods were tested for the enthalpy of hydrogena... |
While reading about the basic character of amines, I came across a note which said that $\ce{CH3-CH2-NH2}$ is more stable than $\ce{CH3-NH2}$ as $\ce{C2H5}$ is a stronger +I group than $\ce{CH3}$.
However, according to what I know, isn't $\ce{CH3}$ a stronger +I group as in a longer chain the +I effect dies out? |
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