instruction stringlengths 15 21.8k |
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It looks to me like the left one is just mistaken.
It looks like who made the image took D-glucose and just flipped the 5-OH.
The result? The molecule at left is not glucose, but L-Idose! |
It looks to me like the left one is just wrong.
It looks like who made the image took D-glucose and just flipped the 5-OH.
The result? The molecule at left is not glucose, but L-Idose! |
Can anyone suggest a pH-responsive polymer, which is immiscible in water (polar solvent) but miscible in oil (e.g vegetable oil)?
I want to study the change in the density of such polymers when they are subjected to changing pH.
**Edit:**
I'm having a biphasic system of oil & water, and want to study the visc... |
In an electrochemical cell, increasing the concentration of reactants will increase the voltage difference, as you have indicated. A higher concentration of reactant allows more reactions in the forward direction so it reacts faster, and the result is observed as a higher voltage.
If you have adjusted the cell volum... |
One key problem with astatine is that it's incredibly unstable. There are no known stable isotopes, and the longest-lived has a half-life of ~8 hours. So no one has been able to (yet) prepare enough to make real measurements. Thus, we don't know for sure whether solid At is diatomic (like the other halogens) or monatom... |
Can someone suggest me a list of polymers or some paper where I may find polymers that are soluble in oils like silicon oil, mustard oil, coconut oil, bean oil or petroleum ether, etc.? |
I’m studying chemistry, and I am learning about chromatography.
But I’m confused about how chromatography is used to ‘separate and purify’ substances.
I’ve learnt about chromatography using chromatography paper, where the spots of solutions travel up the paper, which is dipped in a solvent.
[![Chromatography ... |
How is chromatography used to purify substances? |
Amorphous solid possess short-range order but no long-range order (e.g. amorphous silica, the short-range order is originated from the tetrahedral bonding between Si and O). **Is it possible to have multiple domains with different short-range orders in one amorphous solid?**
If so, should we treat this solid as a s... |
Is an amorphous solid a single phase? |
I am studying chemistry, and I am learning about chromatography.
But I am confused about how chromatography is used to ‘separate and purify’ substances.
I have learnt about chromatography using chromatography paper, where the spots of solutions travel up the paper, which is dipped in a solvent.
[![Chromatogra... |
How is chromatography used to separate and purify substances? |
Generally, all chromatography is done on silica gel. It's the exact same procedure for TLC (thin layer chromatography), except that instead of paper you have a thin layer of glass covered with silica. What can be done in that case is scraping the spots, then extracting the product with organic solvents and filtration. ... |
For a molecule with 2 chiral centres, the following are diastereomers:
S,R and S,S
S,R and R,R
R,S and S,S
R,S and R,R
I notice that only one chiral centre has been flipped to form these pairs.
<br><br>
The following are either enantiomers or meso compounds:
S,R and R,S
S,S and R,R
I notice ... |
I have recently been studying the following mechanism recommended by another user from the following DOI: https://doi.org/10.1016/j.tet.2004.06.026. In this paper, the following mechanism is proposed (I am only focusing on the proposed mechanism in EtOH)
----------
[![Mechanism from Published Paper][1]][1]
... |
>Could we generalise that flipping an even number of chiral centres always gives either an enantiomer or the same molecule if it's a meso compound, and flipping an odd number of chiral centres always gives a diastereomer?
No. The generalization is slightly different: Comparing chiral centers in two stereoisomers wit... |
I recently worked on a lab which involved the following reaction:
HCL(aq) + CuO(s) --> CuCl2(aq) + H2O(l)
In my description of the reaction I wrote the following
"The equation shown above represents a multi–step reaction between copper (II) oxide and hydrochloric acid in aqueous solution. To predict the produc... |
I know that a very similar question has already been asked here and a very competitive and useful answer has been provided (see [here][1]). However, that previous question was related to the total electron density whereas I am interested in plotting the radial probability distribution function of a given single orbital... |
How to obtain the radial probability distribution function of a given orbital from a quantum chemical calculation? |
I know that a very similar question has already been asked here and a very competent and useful answer has been provided (see [here][1]). However, that previous question was related to the total electron density whereas I am interested in plotting the radial probability distribution function of a given single orbital. ... |
I [read][1] that brewed tea contains a relatively large concentration of Fluorine.
Fluorine can have negative health effects such as [Skeletal Fluorosis][2]. **EDIT:** I understand some Fluorine is necessary and has benefits. This is just to inform why I have structured this hypothesis. I am interested in the chemis... |
I [read][1] that brewed tea contains a relatively large concentration of Fluorine.
Fluorine can have negative health effects such as [Skeletal Fluorosis][2]. **EDIT:** I understand some Fluorine is necessary and has benefits. This is just to inform why I have structured this hypothesis. I am interested in the chemis... |
I'm trying to review how to calculate bond dissociation energy for C-C in ethane, a very simple calculation (or should be).
I get the following Hartree energies for SCF 6-31G(p) for methane, ethane, and H2:
ch4_spe -40.194639920746,
ethane -79.228125042573,
h2 ... |
Ab initio method to calculate C-C bond dissociation energy? |
I have been watching this question with keen interest, but wanted to let someone else go for the bounty -- However it expires tomorrow and no one has answered, so I will give my perspective.
> Why does the exchange interaction in Hartree-Fock theory lower the
> total energy?
The answer is given in the question:... |
I recently worked on a lab which involved the following reaction:
$HCl(aq) + CuO(s) \rightarrow CuCl_2(aq) + H_2O(l)$
In my description of the reaction I wrote the following
"The equation shown above represents a multi–step reaction between copper (II) oxide and hydrochloric acid in aqueous solution. To predic... |
1.Why are they carcinogenic:
From my point of view as a medicinal chemist, polycyclic aromatic hydrocarbons compounds tend to be metabolized by specific cytochrome P450 (CYP 450) isofroms to form highly electrophilic species, which are highly reactive and can react with the DNA of the cell and damage it. Specificall... |
For a molecule with 2 chiral centres, there are four possible combinations, (R,R), (R,S), (S,R) and (S,S). For [example][1], 3-bromo-2-butanol has four stereoisomers: (2R,3R)-3-bromo-2-butanol, (2R,3S)-3-bromo-2-butanol,
(2S,3R)-3-bromo-2-butanol and (2S,3S)-3-bromo-2-butanol.
Of these combinations, the following... |
While going through my AP chem prep book again, I came across questions asking about the color of certain aqueous solutions.
For example: Which of the following substances will produce a colorless aqueous solution?
> **A**) $Zn_2(NO_3)_2$
> **B**) $Cu(SO_4)$
> **C**) $K_2Cr_2O_7$
> **D**) $Co(NO_3... |
Should I use Murexide or eriochrome black T for EDTA titration with milk? I am heating the milk to different temperatures and trying to find how the amount of calcium differs (or doesn't). |
I have some polyethylene spiral wrap that I'm hoping to impregnate with citrus oil as an animal deterrent.
Wikipedia says that polyethylene plastic will pass through "flavourings" fairly easily. It's melting point for the grade I have seems to be around 100C.
Do you think that placing polyethylene and citrus oil ... |
Impregnating polyethylene with oil using pressure cooker? |
I recently worked on a lab which involved the following reaction:
$$\ce{HCl(aq) + CuO(s) -> CuCl2(aq) + H2O(l)}$$
In my description of the reaction I wrote the following
"The equation shown above represents a multi–step reaction between copper (II) oxide and hydrochloric acid in aqueous solution. To predict th... |
Fe(CO)5 is known but [Fe(CO)6]+3 is not known why? |
While going through my AP chem prep book again, I came across questions asking about the color of certain aqueous solutions. For example:
> Which of the following substances will produce a colorless aqueous solution?
> **A**) $\ce{Zn2(NO3)2}$
> **B**) $\ce{Cu(SO4)}$
> **C**) $\ce{K2Cr2O7}$
> **D**) $\ce{... |
Why, if I excited the OH molecule Q-branch transition, my LIF spectrum (recorded during and after the laser pulse) does not result in only Q line being the most prominent, but also P and R lines with delta_J=+-1?
How/why are these coupled? |
Why is the neutral complex Fe(CO)5 known but the cationic carbonyl complex [Fe(CO)6]+3 is not known ? |
Why is the neutral complex $\ce{[Fe(CO)5]}$ known, but the cationic carbonyl complex $\ce{[Fe(CO)6]^3+}$ is not known? |
Why is iron pentacarbonyl known, but iron(III) hexacarbonyl is not? |
Why, if I excited the OH molecule Q-branch transition, my LIF spectrum (recorded during and after the laser pulse) does not result in only Q line being the most prominent, but also P and R lines with $\Delta J = \pm 1?$
How/why are these coupled? |
I have 3-4 metal nitrates as precursors for my coprecipitation reaction. I need to study the behavior of each individual nitrate and also of various combinations at 60 deg Celcius, which is my experiment temperature. Which characterization technique would be most suitable to study the change in each case if any?
Any... |
I have read somewhere that $\ce{H2SO4}$ is used to generate $\ce{HBr},$ and at the other place it is written that it is there to protonate the hydroxyl group. Which fact should I believe ? |
Can we use (KBr + H2SO4) instead of (NaBr +H2SO4) in reaction with alcohol to generate alkyl bromide? |
I have 3-4 metal nitrates as precursors for my coprecipitation reaction. I need to study the behavior of each individual nitrate and also of various combinations at 60 degrees Celsius, which is my experiment temperature. Which characterization technique would be most suitable to study the change in each case if any?
... |
I know that, in the band structure of a solid, the Fermi level is the energy level at which there is a 50% probability of finding an electron (at thermodynamic equilibrium), and that it doesn't have to correspond to an actual energy level (ie it's in the band gap in an insulator).
But Atkins and Shriver's Inorganic Ch... |
Does the Fermi level correspond to the highest occupied energy level? |
I have 3-4 metal nitrates as precursors for my coprecipitation reaction. I need to study the behavior of each individual nitrate and also of various combinations at 60 degrees Celsius, which is my experiment temperature. Which characterization technique would be most suitable to study the change in each case if any?
... |
In an electrochemical cell, increasing the concentration of reactants will increase the voltage difference, as you have indicated. A higher concentration of reactant allows more reactions in the forward direction so it reacts faster, and the result is observed as a higher voltage.
If you have adjusted the cell volum... |
This molecule has the same chemical formula as corrannulene (which also is non-planar) and corrannulene is aromatic, so I'm pretty sure that this molecule should be aromatic too.
[Link to image of the molecule][1]
I tried to analyse it using the MoCubed app on my phone (on my previous posts, I wrote "WebMo" instead o... |
Is the following molecule aromatic or antiaromatic?1 |
Consider an electrochemical cell with an inert Pt working electrode (WE) and some electrolyte that irreversibly decomposes upon oxidation. A minimum potential $E_{min}$ (vs. some reference) needs to be applied to the WE to allow oxidation to occur (but most likely a higher value is required to actually measure a curren... |
Is the thermodynamic stability against reduction/oxidation of an electrolyte dependent on the electrode material? |
1.Why are they carcinogenic:
From my point of view as a medicinal chemist, polycyclic aromatic hydrocarbons compounds tend to be metabolized by specific cytochrome P450 (CYP 450) isofroms to form highly electrophilic species, which are highly reactive and can react with the DNA of the cell and damage it. Specificall... |
Is the following molecule aromatic or antiaromatic? |
I have learnt that you can test if a reaction is thermodynamically feasible by testing if the $E$ (cell voltage) cell is greater than $0$. Surely if a reaction is feasible then the $E$ of cell of the reverse reaction is negative and so not thermodynamically feasible in which case how can a cell be recharged? Taking the... |
How are cells rechargable? |
I have learnt that you can test if a reaction is thermodynamically feasible by testing if the cell voltage $E_\mathrm{cell}$ is greater than $0$. Surely, if a reaction is feasible, then the $E_\mathrm{cell}$ of the reverse reaction is negative, and so not thermodynamically feasible; in which case, how can a cell be rec... |
How to calculate the energy to dissociate a bond into neutral atoms? |
I am studying chemistry, and I am learning about chromatography.
But I am confused about how chromatography is used to ‘separate and purify’ substances.
I have learnt about chromatography using chromatography paper, where the spots of solutions travel up the paper, which is dipped in a solvent.
[ = chemical potential energy + thermal energy
Now, I know that Enthalpy and Internal Energy are different so I really don't understand what my text book is saying.
Also, from searching I understood that U(Internal Energy) = q + w
since w=-p.(delta)V
And H(Ent... |
The internal energy U is the sum of all energies stored in the chemical bonds of the examined sample of matter. It is a potential energy.
The enthalpy H is the same, but with a correction due to the presence of the atmosphere. The difference between H and U is similar to the difference between weight and apparent weig... |
My chemistry textbook says that:
Enthalpy(Internal Energy) = chemical potential energy + thermal energy
Now, I know that Enthalpy and Internal Energy are different so I really don't understand what my text book is saying.
Also, from searching I understood that $\mathrm{U = q + w}$
since, $\mathrm{w = -p \De... |
My chemistry textbook says that:
> Enthalpy (Internal Energy) = chemical potential energy + thermal energy
Now, I know that Enthalpy and Internal Energy are different so I really don't understand what my text book is saying.
Also, from searching I understood that $\mathrm{U = q + w}$
since, $\mathrm{w = -p \... |
This picture shows the electron orbital energies for a hydrogen atom, where each subshell belonging to the same principal quantum number ($n = 1, 2, \cdots$) are on the same level. Is this true for any particle with only one electron? Would, $\ce{Li+}$, for example, have the same orbital energies?
[![Energy levels o... |
Do all single-electron species have the same orbital energies? |
This picture from Ebbing's *General Chemistry* \[1, p. 234\] shows the electron orbital energies for a hydrogen atom, where each subshell belonging to the same principal quantum number ($n = 1, 2, \cdots$) are on the same level. Is this true for any particle with only one electron? Would, $\ce{Li+}$, for example, have ... |
> So what is a "period" in this context?
To answer this directly, **a period is a row of the table.**
As user467 indicates, the repeating periods reflect the filling-up of atomic orbitals. Because the valence electrons (those in the outer shell of an atom) determine many of the chemical properties, the periodic str... |
What happens and what do we observe during this qualitative analysis of bronze? |
I'm trying to find out if a particular paint is considered low VOC. The only piece of data I have available is that the VOC content is $10 \dfrac{\mu mol}{m^3}$. What does that equal in $\mathrm{g/L}$ of paint? |
I'm trying to find out if a particular paint is considered low VOC. The only piece of data I have available is that the VOC content is $\pu{10 \mu mol / m^3}$. What does that equal in $\pu{g/L}$ of paint? |
How can a DPPH assay to measure antioxidant activity of beta carotene be conducted? |
Will dissolving pure linseed oil in ethanol decrease its drying time? |
> Can anyone explain why the exchange contribution to the total energy is negative?
I find it misleading that exchange interaction is treated as something that changes total energy of the system. This lowering of energy is actually due to the Hartree-Fock scheme being in principle inexact, and is not really specific... |
Last week, I tried to conduct electrolysis of brine in my house using copper electrodes and 6V battery. After sometime, the entire solution turned orange/yellow. The yellow substance formed a kind of cloud at first and later it turned to an orange colloid. Does anyone know what the yellow coloured substance might be? |
What is the yellow compound formed in electrolysis of brine? |
I am confused between option (2) and (4). Both lone pairs of nitrogen are localized, so next, I looked at the hybridization of N in each compound. As in (2), the N is sp2 hybridized and therefore is more electronegative, I assumed it would be a wea... |
Which one is the strongest base among the following compounds? |
The acidity of a substance is quantified by the energy it takes to remove a proton from it, $RT \ln(K_\mathrm{a}) = RT \mathrm{p}K_\mathrm{a}$. Thus to find which of these substances is the most acidic you would look up the individual $\mathrm{p}K_\mathrm{a}$ values and list the compounds in ascending order of $\mathrm... |
I am confused between option (2) and (4). Both lone pairs of nitrogen are localized, so next, I looked at the hybridization of $\ce{N}$ in each compound. As in (2), the $\ce{N}$ is $\mathrm{sp^2}$ hybridized and therefore is more electronegative, I... |
Let's have a look at some of the definitions in the gold book and see how they relate to your problem.
> [**proton affinity**](http://goldbook.iupac.org/P04907.html)
The negative of the enthalpy change in the gas phase reaction (real or hypothetical) between a proton (more appropriately hydron) and the chemical s... |
Why when we convert from supersaturated to saturated solution we must use the crystal of the same kind of solute ? |
Why when we convert from supersaturated to saturated solution we must use the crystal of the same kind of solute? |
The question is,why, if we supersaturate solutions of sodium thiosulphate, sodium sulphate or sodium acetate, why we have to use the crystal of respective salt to start the rapid crystallization ?
We need not to. It is just the most natural and the most reliable way to set the crystallization centre.
Similar effect i... |
How can sulphur dioxide and nitric oxide be filtered out from a waste incinerator's smokestacks?
I also want to know what it looks like after it is filtered out. |
How can sulfur dioxide and nitric oxide be filtered out from a waste incinerator's smokestacks? |
Why can't non terminal carbon in a carbon chain does not form ionic bond? |
Nonterminal carbons actually can form ionic bonds or at least bonds with strong ionic character, the latter case being much more common with any sort of carbon. With magnesium at the other end of the bond, for example, the isopropyl Grignard reagent $\ce{CH3CH(MgCl)CH3}$ is [commercially available](https://www.sigmaal... |
Imagine an initial 50%-50% mixture of normal ($\rm H_2 \rm O$) and heavy water ($\rm D_2 \rm O$).
I think, simply mixing them, the result will exponentially converge to an equilibric state, where about a half of the solution is $\rm{HDO}$.
What is the time constant with what the system is going to the equilibric ... |
How quickly is converting a $\rm H_2 \rm O + \rm D_2 \rm O$ mixture to $\rm{HDO}$? |
How quickly is converting a H2O + D2O mixture to HDO? |
I looked up [differential](https://www.lexico.com/definition/differential), but still don't savvy why the books below use 'differential' rather than 'different' and vice versa.
*Advanced Organic Chemistry: Part A: Structure and Mechanisms* by Francis A. Carey, Richard J. Sundberg. [p 211](https://books.google.com/b... |
In antacids like Eno that fizz up when mixed in water, why is the citric acid important? |
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