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If I understood correctly, having a protic solvent increases chance of E1 mechanism. But I can not rationalize this because carbocation intermediate is a positively charged molecule, and by surrounding that with a lot more positive protons will make the whole system in an unstable state. Hence it should make it less li... |
Why does protic solvent suggest E1 mechanism rather than E2? |
Peptide bonds are formed as such:
[![img][1]][1]
Aspartic acid, glutamic acid and lysine all contain either one extra $\ce{-COOH}$ or $\ce{-NH2}$ group in them. **Why does that extra group not participate in peptide bond formation?** For reference, the structure are given below:
[![enter image description here][... |
[![enter image description here][1]][1]
From these two molecules in question, (C) should be more unstable as it is in a *cis*-configuration. The *t*-butyl and methyl groups being on the same side of the ring would exert a larger steric force on each other as compared to the trans configuration. However, (D) is menti... |
**Equilibrium in aqueous solution**
In aqueous solution (such as our digestive tract), the equilibrium of the reaction as written is on the side of the reactants. Digestive enzymes catalyze the hydrolysis of peptide bonds, showing that they are not thermodynamically stable in water. However, in the absence of cataly... |
Peptide bonds are formed as such:
[![img][1]][1]
Aspartic acid, glutamic acid and lysine all contain either one extra $\ce{-COOH}$ or $\ce{-NH2}$ group in them. **Why does that extra group not participate in peptide bond formation?** For reference, the structure are given below:
[![enter image description here][... |
**Equilibrium in aqueous solution**
In aqueous solution (such as our digestive tract), the equilibrium of the reaction as written is on the side of the reactants. Digestive enzymes catalyze the hydrolysis of peptide bonds, showing that they are not thermodynamically stable in water. However, in the absence of cataly... |
I came across a question which involved non linear tetra atomic gasses.
In it the value of specific heat capacity at constant volume was given as
**9R** , added up as
**3/2R+3/2R+6R=9R**
Now i know 6R is Cv for tri atomic gasses but why do we add the two 3/2R terms?
Also how does being l... |
Why does C3H6 gas when compressed (in a centrifugal compressor) comes out with a pressure of 16 bar and 90 degrees celsius and when it is a mixture of C3H6 liquid/gas stored inside of a vessel reaches also the 16 bar but at a lower temperature of around 38 degrees celsius?
I know that when it is a vessel with stored... |
I have no idea what's happening as in the product (the answer is (**a**)) there is a new ring being formed on the left benzene. But as I studied after $\ce{H2O}$ leaves, a carbocation is then formed on stabilized by the right rin... |
Is Pinacol rearrangement the source for the ring expansion? |
I have a lot of profile products with the logotype of the company handing them out printed on them. In some situations I don't like to show these logos. However, it is stupid to bin working products for this reason so I would like to remove the print on them.
What solvent can be used for this purpose? What solvent i... |
What can I use to remove print from hard surfaces? |
In the reaction $\ce{N2 (g) + O2(g) -> 2NO (g)}$
my textbook<sup>\[1]</sup> says $q_v$ and $q_p$ are not the same, without any explanation.
I know that
\begin{align}
\Delta U &= q_p + w\\
\Delta U &= q_p - P\Delta V\\
\Delta U &= q_p - Δn_\mathrm{gases}RT
\end{align}
I also know that
$$\Delta U = q_v.$$... |
Is the heat for constant pressure the same as for constant volume in the formation of nitric oxide? |
In a titration to determine the amount of vitamin C in an orange juice sample, the following were mixed with water:
- oxalic acid
- potassium iodide
- starch
- acetic acid
Then, the mixture was titrated with a solution of N-Bromosuccinimide until the solution turn dark as the starch/iodine/iodide inclusion com... |
In a titration to determine the amount of vitamin C in an orange juice sample, the following were mixed with water:
- oxalic acid
- potassium iodide
- starch
- acetic acid
Then, the mixture was titrated with a solution of N-Bromosuccinimide until the solution turned dark as the starch/iodine/iodide inclusion c... |
There are really two parts to your question - one is to interpret the wikipedia entry, the other is the more general question about the transition of methane from the parent molecule to the ionized $\ce{CH4+}$.
For the first question, I believe the author has muddled the explanation a bit (though it's of course jus... |
Why does $\ce{C3H6}$ gas when compressed (in a centrifugal compressor) comes out with a pressure of $\pu{16 bar}$ and $\pu{90 °C},$ and when it is a mixture of $\ce{C3H6}$ liquid/gas stored inside of a vessel reaches also the $\pu{16 bar},$ but at a lower temperature of around $\pu{38 °C}?$
I know that when it is a ... |
I came across a question which involved non linear tetra atomic gasses.
In it, the value of specific heat capacity at constant volume was given as
$9R,$ added up as
$$\frac 3 2 R + \frac 3 2 R + 6R = 9R$$
Now I know $6R$ is $C_V$ for triatomic gasses, but why do we add the two $\frac 3 2 R$ terms?
... |
Glycerol has 3 carbon atoms and succinic acid has 4. So you need (apart from some redox reactions) a way to add another carbon atom.
Also, succinic acid appears in the citric acid cycle. What you have to research are [anaplerotic reactions][1]. When you remove any of the metabolites (like succinic acid) from the cyc... |
> Is it possible to calculate the 'overall' redox potential of a system?
No, it is impossible. You can have a situation where a cellular compartment contains a high ratio of $\ce{NAD+:NADH}$ (i.e. favoring oxidation) and a low ratio of $\ce{NADP+:NADPH}$ (i.e favoring reduction). This is advantageous for the cell be... |
Different enzymes specialize to work on different size ranges. If the fatty acid is too short, it might not bind to enzymes that work on large fatty acids. An enzyme capable of binding short fatty acids might have most binding determinants targeting the CoA moiety instead of the fatty acid itself.
> At what point wo... |
> What is the definition of a “Simple enzyme” exactly?
This is not a term that is commonly used. There are commonly used terms for an enzyme lacking its cofactor (apoenzyme) and having its cofactor (holoenzyme). Also, the term "enzyme complex" is used for the enzyme bound (non-covalently) to other molecules.
>Doe... |
> Is the computation same and I just need to subtract a molecule of FADH2 per unsaturation (double bond)?
Definitely subtract a molecule of $\ce{FADH2}$. After all, you are reducing the unsaturated fatty acid to make a saturated fatty acid before oxidizing it all the way to carbon dioxide. You would also have to che... |
Old question, but in the interim Cody's lab has released [this video](https://www.youtube.com/watch?v=KH46r9Fvla4) (among others) on tasting heavy water. His conclusion was that $\ce{^2H_2}\ce{^{16}O}$ tasted sweeter than $\ce{^1H_2}\ce{^{16}O}$ but $\ce{^1H_2}\ce{^{18}O}$ didn't. He wasn't able to tell the difference ... |
We have the following reactions:
\begin{align}
&\overset{k_1}{\longrightarrow}A\overset{k_2}{\longrightarrow}{B+C}\\
&C \overset{k_4}{\longrightarrow} 2D \overset{k_5}{\longrightarrow}{C}\\
&B \overset{k_3}{\longrightarrow}\\
&D \overset{k_6}{\longrightarrow}
\end{align}
Let $\alpha(t), \beta(t), \gamma(t), \del... |
From studying $\beta$-oxidation of free fatty acids, I've learned how to compute for the ATP equivalence of even-chain and odd-chain free fatty acids.
What really bothers me now is how to compute for the ATP equivalence of an unsaturated fatty acid. Since one of the major difference of the process is in unsaturated ... |
How to compute the number of ATP molecules that can be produced from breaking down an unsaturated free fatty acid? |
> Is the computation same and I just need to subtract a molecule of FADH2 per unsaturation (double bond)?
Definitely subtract a molecule of $\ce{FADH2}$. After all, you can skip the first of the the four steps in each cycle of remove two carbons (formation of double bond, adding water across the double bond, oxidizi... |
In a titration to determine the amount of vitamin C in an orange juice sample, the following were mixed with water:
- oxalic acid
- potassium iodide
- starch
- acetic acid
Then, the mixture was titrated with a solution of N-bromosuccinimide until the solution turned dark as the starch/iodine/iodide inclusion c... |
In the above question I was asked to compare the basic strength order.
So i did it like this
The Nitrogen in I and II will not participate in resonance so the only effect it could produce is inductive (-I) .
Now the compound IV has less resonati... |
We have the following reactions:
\begin{align}
&\overset{k_1}{\longrightarrow}A\overset{k_2}{\longrightarrow}{B+C}\\
&C \overset{k_4}{\longrightarrow} 2D \overset{k_5}{\longrightarrow}{C}\\
&B \overset{k_3}{\longrightarrow}\\
&D \overset{k_6}{\longrightarrow}
\end{align}
Let $\alpha(t), \beta(t), \gamma(t), \del... |
I know a fluorescent lamp works by emitting UV first and then the specific substance inside absorbs UV and finally emits visible light. An object may emit infrared under sunlight due to heating. But those examples are absorbing short wavelength of EM and then reemitting a longer one. Is there a substance that can do th... |
We have the following elementary reactions:
\begin{align}
&\overset{k_1}{\longrightarrow}A\overset{k_2}{\longrightarrow}{B+C}\\
&C \overset{k_4}{\longrightarrow} 2D \overset{k_5}{\longrightarrow}{C}\\
&B \overset{k_3}{\longrightarrow}\\
&D \overset{k_6}{\longrightarrow}
\end{align}
Let $\alpha(t), \beta(t), \gam... |
Glycerol has 3 carbon atoms and succinic acid has 4. So you need (apart from some redox reactions) a way to add another carbon atom.
Also, succinic acid appears in the citric acid cycle. What you have to research are [anaplerotic reactions][1]. When you remove any of the metabolites (like succinic acid) from the cyc... |
How would I measure the Carbon Dioxide content in Coca Cola over a period of time? |
I recently had to do an experiment where we had to make a racemic mixture of D and L complexes and then resolve the enantiomers, and measure the optical rotation of the racemic mixture, and the individual salts. After that we had to calculate the specific rotation in case.
However, when reading about optical activit... |
Is specific rotation defined for mixtures of enantiomers or meso compounds? |
My problem is explained quite easily: I have no experience with ion exchange resins but I would like to test something out in order to exchange my sulfate ions in solution for nitrate (can also be perchlorate or tetrafluoroborate or something similar). Has anybody worked with such resins? Is there anything available on... |
My problem is explained quite easily: I have no experience with ion exchange resins but I would like to test something out in order to exchange my sulfate ions in solution for nitrate (can also be perchlorate or tetrafluoroborate or something similar). Has anybody worked with such resins? Is there anything available on... |
In a titration to determine the amount of vitamin C in an orange juice sample, the following were mixed with water:
- oxalic acid
- potassium iodide
- starch
- acetic acid
Then, the mixture was titrated with a solution of N-bromosuccinimide until the solution turned dark as the starch/iodine/iodide inclusion c... |
In the above question I was asked to compare the basic strength order.
So I did it like this:
The Nitrogen in **I** and **II** will not participate in resonance so the only effect it could produce is inductive (-I) .
Now the compound **IV** ha... |
I'm a physicist, so apologies if the answer below is in a foreign language; but this was too interesting of a problem to pass up. I'm going to focus on a particular question: If we have oxygen and nothing else in a box, how strong does the magnetic field need to be to concentrate the gas in a region? The TL;DR is t... |
Building on [@DrMoishe Pippi's proposed technique](https://chemistry.stackexchange.com/a/125266/16035) though I can't guarantee precision, you could try to use something else to absorb CO2 besides a cold trap.
I propose that you try a [carbon dioxide scrubber](https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber). ... |
Measure concentration in a fixed volume of air
--
Easiest way might be to put it in a sealed impermeable bag or box and measure the CO2 concentration over time. Home hobbyists use something like the MG-811 CO2 sensor or a simple non-dispersive optical sensor and connect it to a Raspberry Pi or Arduino using an anal... |
Measure concentration in a fixed volume of air
--
Easiest way might be to put it in a sealed impermeable bag or box and measure the CO2 concentration over time. Home hobbyists use something like the MG-811 CO2 sensor or a simple non-dispersive optical sensor and connect it to a Raspberry Pi or Arduino using an anal... |
I have been told that equivalent weight of h2o2 =molecular weight if h2o2 as it's n-factor is 1(from balanced equation)
But in my book it's given
Molarity=V/11.2
Normality=V/5.6
Why are the different if equivalent and molecular weights are equal? |
What is the relation between volume strength and normality of h2o2? |
I have been told that
$$\text{equivalent weight of }\ce{H2O2} =\text{molecular weight of } \ce{H2O2}$$
as it's n-factor is $1$ (from balanced equation).
But in my book it's given that
Molarity=$\dfrac V {11.2}$
Normality=$\dfrac V {5.6}$
Why are they different if equivalent and molecular weight... |
What is the relation between volume strength and normality of $\ce{H202}$? |
I have been told that:
$$\text{equivalent weight of }\ce{H2O2} =\text{molecular weight of } \ce{H2O2}$$
as it's $n$-factor is $1$ (from balanced equation).
But in my book it's given that:
>Molarity $= \frac {V }{11.2}$
>Normality $= \frac {V} {5.6}$
Why are they different if equivalent and molec... |
What is the relation between volume strength and normality of H2O2? |
In my chemistry notes the teacher gave me the note that reaction of alkali, alkaline earh metals' reactivity with water, acids(e.g. H2S) increases down the group and bases(e.g.NH3) decreases down the group,
And also I have some doubts that
-alkali metals such as Li first react with water and produce oxides first ... |
Does reaction of alkali and alkaine earth metals' reaction with water an acid-base reaction? |
Measure concentration in a fixed volume of air
--
Easiest way might be to put it in a sealed impermeable bag or box and measure the CO2 concentration over time. Home hobbyists use something like the MG-811 CO2 sensor or a simple non-dispersive optical sensor and connect it to a Raspberry Pi or Arduino using an anal... |
We have the following elementary reactions:
\begin{align}
&\overset{k_1}{\longrightarrow}A\overset{k_2}{\longrightarrow}{B+C}\\
&C \overset{k_4}{\longrightarrow} 2D \overset{k_5}{\longrightarrow}{C}\\
&B \overset{k_3}{\longrightarrow}\\
&D \overset{k_6}{\longrightarrow}
\end{align}
Let $\alpha(t), \beta(t), \gam... |
The periodic table I understand is arranged by order of increasing atomic number after Henry Moseley's X-ray experiment.
But I also learned that the periodic table also has its shape due to the types of subshells present in certain sections called blocks of the table.
However, I still do not understand who sha... |
Which gas would behave most like ideal gas and why? : H2 He CO2 |
I'm an electrical engineer by trade and I am trying to solve a problem I found in some old course notes.
Given is a reversible, homogeneous reaction:
$\ce{ A + 2B <=> C + 3D }$
A solution of 0.02 moles of A and a solution of 0.3 moles B are added together. The solution is lengthened until 1.0 liters. At equi... |
I understand that in solution. transition metals form coloured ions, but what about the transition metals in solid compounds that are coloured- is this also due to d-d transition?
can you give any examples of transition metals bonded to ligands in a solid state? |
Among hydrogen, helium and carbon dioxide, which gas would behave most like ideal gas and why? |
Indeed, even in solid solutions, coordinated transition metals can be the source of colour.
The clearest examples are [gemstone sapphires](https://en.wikipedia.org/wiki/Sapphire). The main component (generally >98% by weight) of sapphires is just [aluminium oxide](https://en.wikipedia.org/wiki/Aluminium_oxide) ($\ce... |
*Edit*: In this answer I've focused on solid solutions of transition metals, which are kind of half-way between pure transition metal solid compounds, and aqueous solutions of transition metal compounds (though more difficult to describe than either extreme...). I see now this is not necessarily what you were asking ab... |
I am studying chemistry of tranquilizers, in that an important class is of barbiturates, which are also hypnotics. The structure of Barbituric acid and veronal, are similar, except veronal has two ethyl groups instead of hydrogen at lone $sp^3$ hybridised carbon. How can I convert Barbituric acid to veronal?
I thou... |
I'm an electrical engineer by trade and I am trying to solve a problem I found in some old course notes.
Given is a reversible, homogeneous reaction:
$\ce{ A + 2B <=> C + 3D }$
A solution of 0.2 moles of A and a solution of 0.3 moles B are added together. The solution is lengthened until 1.0 liters. At equil... |
A colleague of mine who occasionally does HPLC in a biochemistry lab discovered that a C18 column was not properly flushed after the previous experiment.
It appears that the column was stored for several weeks capped with aqueous phosphate buffer inside.
The main concern is partially crystallized phosphate as well ... |
How to recover C18 column after prolonged exposure to phosphate buffer? |
This is the molecule I know as epoxypropane:
<img src="https://i.stack.imgur.com/nKo1Q.png" width="200">
In my neck of the woods ([example](https://doi.org/10.1103/PhysRevX.9.031002)), this molecule is used as one of the standard examples of small chiral molecules. The name 'epoxypropane' makes a heck of a lot of... |
Why is the name 'propylene oxide' preferred for epoxypropane? |
> why is 'propylene oxide' the preferred name for epoxypropane?
Propylene oxide is not the "preferred" IUPAC name (PIN): Wikipedia lists the PIN as 2-methyloxirane, which is in line with the 2013 IUPAC recommendations.
> why is epoxypropane the only isomer encompassed by the designation 'propylene oxide'?
It's... |
I used also iron, nickel, zinc, copper. However, cobalt gives the easiest and straight forward yield of nitrides (XPS and SAED verified).
It is so easy to get cobalt nitride that I don't even have to use high purity nitrogen as I need with $\ce{Fe},$ $\ce{Ni},$ $\ce{Zn},$ $\ce{Cu}.$
Is there any reason for that? Is... |
Why is the entropy of container A the greatest (the answer is B<C<A)? |
Why is the entropy of container A the greatest? |
In mass spectrometry, 1-pentanol can be observed to have no peak at m/z = 59, whilst 3-pentanol can be observed to have a peak at m/z = 59
Cleary 3-pentanol peaks at m/z = 59 due to cleavage creating CH3CH2CHOH | CH2CH3
Why is this the case, as isn't 1-pentanol able to form the fragment CH2CH2CH2OH by cleaving at... |
I also agree with Karsten Theis that $\ce{He}$ would show more ideal behavior than that of $\ce{H2}$ for longer temperature range, just based on their boiling points. The boiling point of helium (~$\pu{4 K}$ or $\pu{-269 ^\circ C}$ at $\pu{1 atm}$) is more close to absolute zero temperature ($\pu{0 K}$) than that of $\... |
>In mass spectrometry, 1-pentanol can be observed to have no peak at $m/z = 59$, whilst 3-pentanol can be observed to have a peak at $m/z = 59$.
Cleary 3-pentanol peak at $m/z = 59$ is due to the cleavage creating $\ce{CH3CH2CHOH | CH2CH3}$
Why is this the case, as isn't 1-pentanol able to form the fragment $\ce{... |
From what I've gathered in my lectures, enolates are enolised cabonyl compounds. However e.g. a nitrile with an H on the alpha C can undergo enolisation. Is the resulting molecule called an enolate or an enolate equivalent, or something else? |
Are all enolised molecules called enolates? |
As per noble gas configuration Na^+ should be more stable than Na . But at the same time Na^+ has a positive charge so it will be easily attracted by negative charge while Na will remain unaffected in presence of negative charge , so accordingly should not Na more stable than Na^+? Please help me get out of this confus... |
Why doesn't H₄CO₄ exist as a stable compound? |
Why doesn't $\ce{H4CO4}$ exist as a relatively stable compound? Its heavier homologue $\ce{H4SiO4}$ seems to exist. |
As per noble gas configuration $\ce{Na+}$ should be more stable than $\ce{Na}$. But at the same time $\ce{Na+}$ has a positive charge so it will be easily attracted by negative charge while $\ce{Na}$ will remain unaffected in presence of negative charge. So accordingly, should not $\ce{Na}$ more stable than $\ce{Na+}$?... |
What is more stable, Na+ or Na? |
A gas which is a oxidizing agent as well as a reducing agent? |
Which gas is a oxidizing agent as well as a reducing agent? |
I'm a real beginner in chemistry and I'm currently reading about redox reactions. I'm quite confused about this simple redox reaction:
>${Iron(III)-ion+Iodide \space ion \rightleftharpoons Iron(II)-ion+Iodine}$
>\begin{array}{|c|c|c|c|c|c|}
\hline
Oxidation numbers& +3 & -1 &\rightleftharpoons & -1 & 0\\ \hline
... |
**Why do so many lanthanide series elements have exceptional electromagnetic properties?** They can form strong magnets and are also used in superconducting applications. The number of elements in the lanthanide series displaying these properties is far higher than other blocks in the periodic table
One thought is t... |
Apologies if this seems like a silly question.
Rare earth elements (the 4d series) are called by the names Lanthanides or Lanthanoids interchangeably. The same applies for the 5d series, which are called Actinides or Actinoids.
**Which one of these two terms is more preferred?** Is there an IUPAC directive prefe... |
I know that the constant **a** represents the attractive forces between the molecules while the constant **b** represents the size/repulsion between them. Does that mean that **a** and **b** are "inversely proportional" or are they independent of each other? If we have two gases and we can compare their sizes and attra... |
How are the Van der Waals constants a and b related to each other? |
I want to extract elemental silicon from pure silicon dioxide powder.
From what I've read, one way to do it is by adding carbon from graphite at very high temperatures, which is difficult.
A better way to do it is to mix with magnesium powder and heat it to about 800 C.
Some places mention the use of a hydro... |
>In mass spectrometry, 1-pentanol can be observed to have no peak at $m/z = 59$, whilst 3-pentanol can be observed to have a peak at $m/z = 59$.
Clearly the 3-pentanol peak at $m/z = 59$ is due to the cleavage creating $\ce{CH3CH2CHOH | CH2CH3}$
Why is this the case, as isn't 1-pentanol able to form the fragment ... |
I'm a real beginner in chemistry and I'm currently reading about redox reactions. I'm quite confused about this simple redox reaction:
>${\text{Iron(III) ion + Iodide ion} \rightleftharpoons \text {Iron(II) ion + Iodine}}$
>\begin{array}{|c|c|c|c|c|c|}
\hline
\text{Oxidation numbers}& +3 & -1 &\rightleftharpoons ... |
I want to extract elemental silicon from pure silicon dioxide powder.
From what I've read, one way to do it is by adding carbon from graphite at very high temperatures, which is difficult.
A better way to do it is to mix with magnesium powder and heat it to about $800 ^\circ \rm C$.
Some places mention the u... |
How to make elemental silicon? |
The following website shows constants for the Van der Waals equation (a and b): https://en.m.wikipedia.org/wiki/Van_der_Waals_constants_(data_page). As shown, hexane has a higher attraction constant (a) than water (24.71 vs 5.536), but water has a higher boiling point than hexane, so intuitively water would have strong... |
Why don’t compounds with high boiling points not necessarily have high attraction constants (a) in the Van der Waals equation? |
In GAMESS's thermochemistry output, which numbers mean what?
The [gaussian docs](http://gaussian.com/thermo/) have a nice description of how to use thermochemistry data, but for gaussian's output. This appears to be different, eg, it mentions thermal corrections to energy, enthalpy, and Gibbs free energy, but GAMESS o... |
How do I interpret GAMESS thermochemistry output? |
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