instruction stringlengths 15 21.8k |
|---|
In my PhD-work, we are trying to develop LC-MS/MS methods for targeted analysis. Usually, I determine my quantifying ion/fragment based on a few different criteria:
* If there is a 13C internal standard of identical structure, stick with the same fragment for both.
* If not, look for the lowest noise/highest are... |
I have recently stumbled upon a question I can't seem to solve :
> Chlorine can also be used to synthesise a bromine-containing oxoanion that is mainly used in continuous or batch dyeing processes. When chlorine is passed through an aqueous solution containing potassium hydroxide and potassium bromide, the bromide ... |
Based on the above picture, it seems that there are four. However, I have two questions:
1. Aren't the top right and bottom left forms simply mirror images of each other, and thus considered the same?
2. If not, would an alternate version of the top left ... |
Ionic solids like NaCl, KOH, KBr, PbCl2 and KBrO3 have ratios of individual elements, but the "molecule", if you could use that term to describe it, would be the whole crystal, because all the ions are attracted to nearby ions, ad infinitum.
The white solid could be written as "K23.4% Br47.8% O28.8%", and every tim... |
According to [Wikipedia][1], the melting point(mp) of Al is 933.47K while the mp of Mg is 923K, yet the mp of Na is merely 370.87K.
With huge difference between Na and Mg but small difference between Mg and Al in mind, I tried to search for valid explanations but yet failed to find any satisfactory answers. Can anyone ... |
According to [Wikipedia][1], the melting point(mp) of Al is 933.47K while the mp of Mg is 923K, yet the mp of Na is merely 370.87K.
With huge difference between Na and Mg but small difference between Mg and Al in mind, I tried to search for valid explanations but yet failed to find any satisfactory answers.
Can anyo... |
I have to ask this here because I asked literally everybody I know I still disagree with them
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/WtQt7.png
I'm convinced the answer is C.
The enthalpy of this reaction for 4 moles of NO is -905.2, to find the enthalpy for 1 mole of NO w... |
I have to ask this here because I asked literally everybody I know and I still disagree with them.
> Using the information in the table below, calculate the heat of released from the following reaction in $\pu{kJ}$ per $\pu{g}$ of $\ce{NO}.$ (Mw. of $\ce{NO}$ is $\pu{30.01 g/mol})$
> $$\ce{4 NH3(g) + 5 O2(g) -> 6... |
I came across the following question:
Sucrose on treatment with conc. $\ce {HCl}$ produces?
The answer is given as levulinic acid.
So how exactly does sucrose produce levulinic acid? |
How is levulinic acid formed from sucrose? |
I have a mixture of $\ce{NO2(g)}$ and $\ce{N2O4(g)}$ at $63\ \mathrm{^\circ C}$ and $750\ \mathrm{mmHg}$. I need to find the weight percent of the first compound. Density $d=1.98\ \mathrm{g/L}$.
I assumed that we have $M=aM_1+bM_2$ where $M_1$ and $M_2$ are the molar masses of the first and second compound. I know t... |
My [data source][1] gives the following values for various enthalpies of formation and combustion:
formation of CO2 = -393.5
formation of HCOOH = -425
combustion of HCOOH = -254.3
Wikipedia gives liquid water's enthalpy of formation as -285.
All units are kJ/mol.
I guess the reaction is $4 \mathrm{HCO... |
I am working on modifying the reaction below. I am adding the sulfonate (ignore the sulfonic acid groups shown) groups so that polysubstitution of the phloroglucinol does not occur. In terms of the reactivity of the sulfonate, there should not be any issue, as it is not acidic and will not interfere with the potassium ... |
I'm not very sure if the required amount of oxygen (I assume) can be found by only knowing the amounts of the produced subtances after a combustion.
To illustrate this I found this problem:
> $1.14\,kg$ of octane $C_{8}H_{18}$ is burned with a certain amount of
> air. The resulting products from the combustion a... |
Is it possible to obtain the amount of air required for a combustion analysis? |
I am working on modifying the reaction below. I am adding the sulfonate (ignore the sulfonic acid groups shown) groups so that polysubstitution of the phloroglucinol does not occur. In terms of the reactivity of the sulfonate, there should not be any issue, as it is not acidic and will not interfere with the potassium ... |
I am working on modifying the reaction below. I am adding the sulfonate (ignore the sulfonic acid groups shown) groups so that polysubstitution of the phloroglucinol does not occur. In terms of the reactivity of the sulfonate, there should not be any issue, as it is not acidic and will not interfere with the potassium ... |
I've just begun reading about halonium ions and I noted that only the first four halogens are acknowledged to be able to form halonium ions, but hydrogen astatide can be formed.
I can't seem to find any answers on the internet, but knowing that astatine is super reactive and radioactive, I suppose it may be due to t... |
Does a halonium ion for astatine exist? |
I am working on modifying the reaction below. I am adding the sulfonate (ignore the sulfonic acid groups shown) groups so that polysubstitution of the phloroglucinol does not occur. In terms of the reactivity of the sulfonate, there should not be any issue, as it is not acidic and will not interfere with the potassium ... |
I'm currently working on a project using [Iron(III) acetylacetonate][1], which in the wikipedia page it's written [Tris(acetylacetonato)iron(III)][2], and it says it's the IUPAC name, maybe it's obvious but I'm a little confused about the nomenclature, why acetylacetonato instead of acetylacetonate, couldn't it be Tris... |
So this answer does seem right. In the reaction I have drawn here, a similar logic prevails, you would be shocked to know that the equilibrium shifts to the right here in an ethanolic solution. The reason simply is the very high $C=O$ bond energy. $C=O$ has a bond energy of more than $100 kJ/mol$ than the $C=N$ and $C=... |
For example, my book says that the acidic character of halogen acids increases on going down the group because the bond strength decreases, making it easier to release the H+.
But I also know that HI (the last element I'm considering) is a strong reducing agent. Is there any way to explain this?
Won't "release H+" be... |
Is acidic character related to reducing power? |
*(1933) established that polynuclear aromatic hydrocarbons (PAHs) were carcinogenic components of pitch. ... Although less is known about their health effects than about those of PAHs, it is clear that some nitro-PAHs are potent mutagens and carcinogens.* [(1)][1]
*Benzene and polynuclear hydrocarbons
containing mo... |
*(1933) established that polynuclear aromatic hydrocarbons (PAHs) were carcinogenic components of pitch. ... Although less is known about their health effects than about those of PAHs, it is clear that some nitro-PAHs are potent mutagens and carcinogens.* [(1)][1]
*Benzene and polynuclear hydrocarbons
containing mo... |
[![enter image description here][1]][1]
This reaction should cause ring closure at either the $o-$ or $p-$ position relative to the methyl substituent on the ring (as methyl is an $o,p-$directing group), giving the following products:
[![Product1][2]][2][![enter image description here][3]][3]
The question is: **... |
*(1933) established that polynuclear aromatic hydrocarbons (PAHs) were carcinogenic components of pitch. ... Although less is known about their health effects than about those of PAHs, it is clear that some nitro-PAHs are potent mutagens and carcinogens.* [(1)][1]
*Benzene and polynuclear hydrocarbons
containing mo... |
> (1933) established that polynuclear aromatic hydrocarbons (PAHs) were
> carcinogenic components of pitch. ... Although less is known about
> their health effects than about those of PAHs, it is clear that some
> nitro-PAHs are potent mutagens and carcinogens.(1)
> Benzene and polynuclear hydrocarbons containing... |
According to [Wikipedia][1], the melting point of $\ce{Al}$ is 933.47K while the melting point of $\ce{Mg}$ is 923K, yet the melting point of $\ce{Na}$ is merely 370.87K.
With huge difference between $\ce{Na}$ and $\ce{Mg}$ but small difference between $\ce{Mg}$ and $\ce{Al}$ in mind, I tried to search for valid exp... |
According to [Wikipedia][1], the melting point of aluminium is 933.47K (660 oC) while the melting point of magnesium is 923K (650 oC), yet the melting point of sodium is merely 370.87K (98 oC).
With huge difference between sodium and magnesium but small difference between magnesium and aluminium in mind, I tried to ... |
I have dissolved baking soda in battery water (de-ionized), in a glass beaker and used a food handling glove (vinyl) as a semi permeable membrane to separate a graphite electrode from a copper electrode. This is for an experiment that will use the copper electrode for the reaction and not the graphite electrode. When I... |
Lewis acidity is a function of electron deficiency on the acceptor atom, which is this case is B and Al respectively
So, of the back donation is better as is the case of B due to better 2p overlap compared to 3p overlap, then the electron deficiency on the B atom should be lesser, as it's deficiency is getting filled ... |
Lewis acidity is a function of electron deficiency on the acceptor atom, which in this case is $B$ and $Al$ respectively
So, of the back donation is better as is the case of $B$ due to better $2p$ overlap compared to $3p$ overlap, then the electron deficiency on the $B$ atom should be lesser, as it's deficiency is ge... |
My book says that the acidic character of halogen acids increases on going down the group because the bond strength decreases, making it easier to release the $\ce{H+}$.
But I also know that $\ce{HI}$ (considering the last element) is a strong reducing agent. Is there any way to explain this?
Won't "release of $\... |
I have dissolved baking soda in battery water (de-ionized), in a glass beaker and used a food handling glove (vinyl) as a semi-permeable membrane to separate a graphite electrode from a copper electrode. This is for an experiment that will use the copper electrode for the reaction and not the graphite electrode. When I... |
I have dissolved baking soda in battery water (de-ionized), in a glass beaker and used a food handling glove (vinyl) as a semi-permeable membrane to separate a graphite electrode from a copper electrode. This is for an experiment that will use the copper electrode for the reaction and not the graphite electrode. When I... |
Most preparations for nitrocellulose from KNO3+H2SO4 mixture require the use of an ice bath during the process of dissolving KNO3 into H2SO4. Last time I did this I omitted this step and the nitrocellulose turned out to be of very low quality, but theres a number of other possible causes I can think of. Therefore, for ... |
I'm currently planning to do a lab experiment about the effect of sugar addition (sucrose) to orange juice on Vitamin C (ascorbic acid), also finding the degradation rate and activation energy required. To measure ascorbic acid concentration, I am going to use iodometric titration but I am wondering if the addition of ... |
Iodometric Titration: Would iodine react with sucrose as well? |
This answer does seem right. In the reaction I have drawn here, a similar logic prevails, you would be shocked to know that the equilibrium shifts to the right here in an ethanolic solution. The reason simply is the very high $\ce{C=O}$ bond energy. $\ce{C=O}$ has a bond energy of more than $\pu{100 kJ/mol}$ than the $... |
I seemingly can't solve the following problem, I've spend over 30 mins on it, no progress, can any of you geniusses give a step by step solution to me? Thank you so much
Problem:
A mixture of aluminium and iron weighing 9,62g reacts with hydrogen chloride in aqueos solution according to the parallel reactions
... |
The line says
>Alkaline metals and their salts impart characteristic colour to an oxidising flame. This is because the heat from the flame excites the outermost orbital electron to higher energy level. When excited electron comes back to the ground state, there is emission of radiation in the visible region of the spec... |
Lewis acidity is a function of electron deficiency on the acceptor atom, which in this case is $B$ and $Al$ respectively
So, of the back donation is better as is the case of $B$ due to better $2p$ overlap compared to $3p$ overlap, then the electron deficiency on the $B$ atom should be lesser, as it's deficiency is ... |
Lewis acidity is a function of electron deficiency on the acceptor atom, which in this case is $\ce{B}$ and $\ce{Al}$ respectively.
Back donation is better as is the case of $\ce{B}$, due to better 2p overlap compared to 3p overlap, then the electron deficiency on the $\ce{B}$ atom should be lesser, as it's deficie... |
I've read that when a carboxylic acid reacts with $\ce{LiAlH4}$ the corresponding alcohol is formed:
[![enter image description here][1]][1]
But when I try to think of the mechanism, I get stuck here:
$\ce{LiAlH4}$ produces $\ce{H-}$. Since $\ce{H-}$ is a strong base it should immediately abstract a proton f... |
*There is a range of elimination reactions with E1cb at one end, E1 at the other end and E2 in between. It is not uncommon for these different reaction pathways to compete with one another. For example, in some elimination reactions, the E1 and E2 pathways can operate in competition with one another. An activation ener... |
I have learnt that the species which have vacant orbital(s) are called electrophiles. But in this case, the nitrogen has a complete octet. The positively charged Nitrogen ion has a valency of 4, of which 2-2 are satisfied by each Oxygen atoms.
Still, NO2+ acts as a nucleophile, why? |
Why is NO2+ is an electrophile? |
> How many distinct dichlorination products can result when isobutane is subjected to free radical chlorination?
I think that three distinct products may result namely
a) 1,1-Dichloro-2-methylpropane
b) 1,2-Dichloro-2-methylpropane
c) 1,3-Dichloro-2-methylpropane
But the book says only two distinct pro... |
Why is NO2+ an electrophile? |
I have learnt that the species which have vacant orbital(s) are called electrophiles. But in this case, the nitrogen has a complete octet. The positively charged nitrogen ion has a valency of 4, of which 2-2 are satisfied by each oxygen atoms.
Still, $\ce{NO2+}$ acts as a nucleophile. Why? |
Why is nitronium ion an electrophile? |
[![enter image description here][1]][1]
This is the organic molecule
and these are the answer choices:
[![enter image description here][2]][2]
I am not sure what the answer it. I know it can't be B because there is no aklyne triple bond. However, shouldn't an alkene only exist in a straight chain? I kn... |
When entropy is a state function and the entropy change for a reversible process is
$$\mathrm dS_\mathrm{rev} = \frac{\delta Q_\mathrm{rev}}{T} = 0,$$
how can an irreversible process be calculated by the same formula? $\delta Q_\mathrm{irr}$ is not a state function, therefore $\mathrm dS_\mathrm{irr}$ cannot b... |
> Identify functional groups of the following organic molecule:
> [![Structure][1]][1]
> **A**. ketone, alkene, carboxylic acid, ester
> **B**. alkyne, ester, carboxylic acid, aldehyde
> **C**. carboxylic acid, alkene, ketone, ester
> **D**. ester, aldehyde, carboxylic acid, alkene
I am not sure what... |
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.
|
pH responsive polymer which is immiscible in water? |
*There is a range of elimination reactions with E1cb at one end, E1 at the other end and E2 in between. It is not uncommon for these different reaction pathways to compete with one another. For example, in some elimination reactions, the E1 and E2 pathways can operate in competition with one another. An activation ener... |
The question: In the lab described below, why did the decolorization reaction described, which should be first order in each of the two reactants, go most slowly when the reactants were most concentrated?
As part of the introduction to our kinetics unit, I asked my students for factors that they thought would influe... |
Why is there a big jump in first ionisation energy between sodium and potassium? |
Having run a saucepan with an aluminium handle through the dishwasher, the handle is producing a dark grey dusty residue, which I assume is an oxide of aluminium. The dishwasher was run with a typical dishwashing detergent as well as some drying agent (potentially).
The residue can be scoured off, leaving the shiny ... |
If both forward and backward reaction rates are equal why is it that only the products are visible to a naked eye? |
In reversible processes in dynamic equilibrium why do we only see the products and not the reactants? |
Why do you think so ?
As I have missed the other answer, this is just a complement to it.
In the equilibrium:
$$\ce{ 2 NO2 <=> N2O4}$$
both are reactants and products at the same time.
If you formally consider products on the right side, then you see by the naked eyes the red-brown reactant.
What is or is not se... |
As we move down in sulphates of group 2 their solubility decreases because their is a drastic decrease in hydration enthalpy as compared to decrease in lattice enthalpy
Does the decrease in lattice enthalpy means decrease in ionic character ?
But according to fazan rule the ionic character should increase or co... |
All the reaction have different concerntration at start . As u have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say disco... |
All the reaction have different concerntration at start . As u have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say disco... |
All the reaction have different concerntration at start . As u have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say disco... |
All the reaction have different concerntration at start . As u have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say disco... |
All the reaction have different concerntration at start . As u have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say disco... |
All the reaction have different concerntration at start . As you have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say dis... |
All the reaction have different concerntration at start . As you have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say dis... |
The question: In the lab described below, why did the decolorization reaction described, which should be first order in each of the two reactants, go most slowly when the reactants were most concentrated?
As part of the introduction to our kinetics unit, I asked my students for factors that they thought would influe... |
All the reaction have different concerntration at start . As you have taken so much excess NaOH it would remain constant. We could look it as you have a solution of 50 ml with 0.05 mM violet red and 0.5M NaOH . You dilute the N times and then to have to compare rates. Threotically we could find that but when we say dis... |
As we move down in sulphates of group 2 their solubility decreases because there is a drastic decrease in hydration enthalpy as compared to decrease in lattice enthalpy.
Does the decrease in lattice enthalpy means decrease in ionic character?
But according to Fajans' rules the ionic character should increase or cov... |
So for multiple bonds to be conjugated, they must be in an alternating
double bond – single bond – double bond, etc arrangement. However, do they need to be continuous? In my textbook, they count the number of conjugated multiple bonds like this:
[![enter image description here][1]][1]
However, for other mole... |
The problem is shown below. I don't understand how can the tonicity of a solution be determined if the solution has multiple solutes dissolved in it.
[![enter image description here][2]][2]
Do I take the total sum of the mass of solutes and divide it by the volume of the solution in both outside and inside of the... |
Is the solution isotonic, hypertonic, or hypotonic? |
Is it possible that strong acids like $\ce{H2SO4}$ behave as weaker ones like $\ce{CH3COOH}$ when the concentration is really high and vice versa for weak acid? And the same question for bases.
By this I am generally referring to pH values.
Why do concentrated acids react more than dilute ones? The degree of ioniza... |
Your analysis of the expectation is correct, and we can look at it more quantitatively in this way:
Since the hydroxide concentration is much higher than the CV concentration in all of the reactions, let's approximate it as unchanging. Assuming the reactions are first-order in each reactant, we have a rate law for the... |
Consider a complex multistep reaction mechanism with several intermediates. There are multiple possible pathways as well as equilibria in solution. One wants to study the reaction mechanism using computational chemistry.
It is easy to calculate the $\Delta G$ and $\Delta G^\ddagger$ of individual reactions, but how ... |
How to manage complex equilibria when studying a mecanism? |
The ammonium chloride dissociates at 317 ° C according to the reaction:
$$\ce{NH4Cl (s) -> HCl (g) + NH3 (g)}$$
reaching a total pressure of 500 mm Hg in equilibrium in a closed container. What will be the total pressure in the equilibrium when a gaseous hydrogen chloride at 500 mm Hg of pressure is introduced into... |
In many places I have come across the following derivation
**Work done in isothermal expansion**
>By first law of thermodynamics
>1. $\mathrm dU=Q+W$
>2. As $\mathrm dU=nC_V\,\mathrm dT$, and in isothermal process $\mathrm dT = 0$
>$\therefore\mathrm dU=0$
>$W=-Q$
i.e heat absorbed is completely ... |
I'm studying the oxidation of guanine using singlet oxygen and one step of the reaction is not very clear to me.
[![Oxidation of guanine][1]][1]
My problem is with the first step: it is a 4+2 Diels–Alder cycloaddition, and Fukui's rules suggest that this kind of reaction doesn't happen photochemically, only therm... |
I have recently been studying the following mechanism recommended by another user from the following DOI: 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]
----------
Pl... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/bqCGr.jpg
In order to overlap, orbital lobes must have the same sign of the wavefunction i.e. they must have the right symmetry. In case 2 in the image above, can therefore E2 elimination not occur? |
Can someone suggest me a list of polymers or some paper where I may find polymers that are soluble in oil? Oils like: Silicon oil, mustard oil, Coconut oil, bean oil or petroleum ether, etc.
Thanks |
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]
... |
In the following cyclopentane deratives, why can't I say that a,b,e have a center of symmetry so they are optically inactive and c as it has a plane of symmetry as shown is also optically inactive? The book tells that only c is optically inactive. |
[![Chiral Alkene][1]][1]
[1]: https://i.stack.imgur.com/THb9S.png
Consider this compound, which is in *E*-configuration and that red asterisk denotes the chiral carbon. If I were to somehow cause the *E*-configuration of the alkene part to *Z*-configuration keeping the rest of the molecule same, would it have... |
From my AP Chem Prep Book:
"What should you do if you spill sulfuric acid on the countertop?"
```
A) Neutralize the acid with vinegar.
B) Sprinkle solid NaOH on the spill.
C) Neutralize the acid with NaHCO3
D) Neutralize the acid withan Epsom salt (MgSO4) solution.
```
The answer given was c - stating... |
Recently in the Chemistry.SE chatroom a user posted this to celebrate the New Year:
[![CaK][1]][1]
[1]: https://i.stack.imgur.com/Q85wL.png
Can Ca and K exist as an ionic compound?
>Ca with atomic number 20, K 19
so 2019 ->**H**appy **N**ew **Y**ear->2020 |
Can Ca and K exist as an ionic compound? |
Recently in the Chemistry.SE chatroom a user posted this to celebrate the New Year:
[![CaK][1]][1]
[1]: https://i.stack.imgur.com/Q85wL.png
Can Ca and K exist as an ionic compound? If not, why is it impossible?
>Ca with atomic number 20, K 19
so 2019 ->**H**appy **N**ew **Y**ear->2020 |
From my AP Chem Prep Book:
> What should you do if you spill sulfuric acid on the countertop?
> **A**) Neutralize the acid with vinegar.
> **B**) Sprinkle solid NaOH on the spill.
> **C**) Neutralize the acid with NaHCO3.
> **D**) Neutralize the acid with an Epsom salt $(\ce{MgSO4})$ solution.
The ans... |
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:... |
We are told that L-Glucose is an enantiomer of D-Glucose, which would mean that they are mirror images of each other. But then we're also told that the L and D forms is determined by the spacial relationship to glyceraldehyde.
Which of the struct... |
Why are there two structures of L-Glucose in the Fischer projection? |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.