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This is a standard exam question pertaining to the kinetics material that is typically presented in a first year general chemistry course. Usually the coverage is restricted to discussion of zero, first and second order kinetics. From the photo of the exam question, the decay is **apparently** first order, i.e., $$\mat... |
When I mix magnesium citrate with hot water, it quickly dissolves and the water becomes transparent. When I do the same with magnesim malate, it does not dissolve, it sinks to the bottom as sand.
The question is how to dissolve the magnesium malate so that the water becomes transparent like with magnesium citrate? |
How to dissolve magnesium malate in water? |
This is a standard exam question pertaining to the kinetics material that is typically presented in a first year general chemistry course. Usually the coverage is restricted to discussion of zero, first and second order kinetics. From the photo of the exam question, the decay is **apparently** first order, i.e., $$\mat... |
This is a **standard exam question** pertaining to the kinetics material that is typically presented in a first year general chemistry course. Usually the coverage is restricted to discussion of zero, first and second order kinetics and this is what gets tested on exams. From the photo of the exam question, the decay i... |
How would one favor the formation of p-TsCl over o-TsCl in the chlorosuflonation of toluene? |
Since a voltaic cell has some internal resistance the voltage measured by the voltmeter connecting the electrodes, is actually lower than the emf of the cell, so how can I measure the EMF of the cell exactly? |
Since a Voltmeter does not account for the internal resistance of a voltaic cell, how can the actual EMF of the cell be measured? |
The Wikipedia article about the Grignard Reaction says that
> The addition of the Grignard reagent to the carbonyl typically proceeds through a six-membered ring transition state.
[![enter image description here][1]][1]
This got me thinking: How was it determined that the Grignard reaction has the ring as a tra... |
How are unstable reaction intermediates determined? |
Chlorosulphonation using $\ce{ClSO3H}$ is an irreversible, electrophilic aromatic substitution reaction.
In the book <a href="https://books.google.co.in/books?id=roI_CwMEcHMC&lpg=PA35&dq=chlorosulfonic%20acid%2C%20chlorosulfonation%20by&pg=PA36#v=onepage&q=chlorosulfonic%20acid,%20chlorosulfonation%20by&f=false">Ch... |
You don't. It's [insoluble in water](https://www.mineralsinc.com/MSDS/MagnesiumMalate_msds.htm).
Being a carboxylic acid salt, it may be introduced into the body by reaction with hydrochloric acid in gastric juice.
Similar data in magnesium citrate, shown [here](https://www.google.com/url?sa=t&source=web&rct=j&u... |
The source of my question is due the nature of a problem which I found misleading in the way how it was presented.
The problem is as follows:
> The molecular weight of hydrogen ($H_{2}$), helium ($He$), nitrogen
> ($N_2$) and oxygen ($O_2$) are $2$, $4$, $28$ and $32$, respectively.
> If $N$ is the number of mo... |
What will be the number of molecules per mole in a set of different gases when compared with hydrogen? |
The source of my question is due the nature of a problem which I found misleading in the way how it was presented.
The problem is as follows:
> The molecular weight of hydrogen ($\ce{H2}$), helium ($\ce{He}$), nitrogen ($\ce{N2}$) and oxygen ($\ce{O2}$) are $2$, $4$, $28$ and $32$, respectively. If $N$ is the num... |
For a fast chemical reaction where reactant A is fed into an agitated solution of reactant B.
Can the selectivity of the reaction be strongly dependent on the location of the feed pipe outlet?
I am not too sure if specific power input has anything to do with it. I can't seem to understand the principles behind th... |
Why doesn't hydrogen peroxide decompose into hydrogen and oxygen? |
According to Elliot, Hathaway & Slade (1966) cited by [this paper][1], Co(II) with nitrite ligands is low spin.
[![enter image description here][2]][2]
So maybe it is just a typo. For d7 low spin, you would expect one unpaired electron.
[1]: http://scripts.iucr.org/cgi-bin/paper?S0567740880005535
[2]: htt... |
I'm asking this because im proving a friend wrong. I get how cyanide ions won't react in an ethanol solvent because the solvent is too reactive but why won't this? |
Why doesn't an aliphatic acyl chloride react with cyanide ions in aqueous sulphuric acid undergo nucleophilic addition elimination? |
Suppose I have a script to calculate the energy of a relatively large molecule like hexamethyldisiloxane:
# method ...
Title
0 1
O
Si 1 1.63776
Si 1 1.63776 2 148.48211
C 2 1.87584 1 107.42571 3 198.44765
... |
How to access implicit bond angles that don't appear in Gaussian's z-matrix input? |
Suppose I have a Gaussian script to calculate the energy of a relatively large molecule like hexamethyldisiloxane:
# method ...
Title
0 1
O
Si 1 1.63776
Si 1 1.63776 2 148.48211
C 2 1.87584 1 107.42571 3 198.44... |
The Wikipedia article about the Grignard Reaction says that
> The addition of the Grignard reagent to the carbonyl typically proceeds through a six-membered ring transition state.
[![enter image description here][1]][1]
This got me thinking: How was it determined that the Grignard reaction has the ring as a tra... |
How are unstable transition states determined? |
Let's take a look at what you're doing specifically for computing the potential difference. The potentials at the cathode and the anode are all relative to some standard. Importantly, it must be the same standard. Let's refer to this as ground.
$$E_{\mathrm{cathode}} = V_{\mathrm{cathode}} - V_{\mathrm{ground}}$$
$... |
Amway makes a product called L.O.C. It is somewhat of a detergent, However, it has been sold as a product that "makes water, wetter". It has been added (as I have been told) to chemicals in crop dusters. It allows the chemicals to spread over the leaves, giving greater surface area of coverage because of loss of surfac... |
Prove that:
$$\left(\frac{\partial Cp}{\partial P}\right)_T = -T \left(\frac{\partial^2 V}{\partial T^2}\right)_P$$
Since $Cp = (\frac{\partial H}{\partial T})_P$
$$\left(\frac{\partial Cp}{\partial P}\right)_T = \frac{\partial}{\partial P} \left(\left(\frac{\partial H}{\partial T}\right)_P\right)_T$$
Using... |
Prove that:
$$\left(\frac{\partial Cp}{\partial P}\right)_T = -T \left(\frac{\partial^2 V}{\partial T^2}\right)_P$$
Since $Cp = (\frac{\partial H}{\partial T})_P$
$$\left(\frac{\partial Cp}{\partial P}\right)_T = \frac{\partial}{\partial P} \left(\left(\frac{\partial H}{\partial T}\right)_P\right)_T$$
Using... |
>Heat of hydrogenation (symbol: $\ce{ΔH_\text{hydro}}$) of an alkene is the standard enthalpy of catalytic hydrogenation of an alkene. (from [Chemistry Libretexts][1]).
**Does the heat of hydrogenation include only the double bonds in an alkene or does it also include other forms of unsaturation, such as rings?**
... |
Suppose I have a Gaussian script to calculate the energy of a relatively large molecule like hexamethyldisiloxane:
# method ...
Title
0 1
O
Si 1 1.63776
Si 1 1.63776 2 148.48211
C 2 1.87584 1 107.42571 3 198.44... |
Suppose I have a Gaussian script to calculate the energy of a relatively large molecule like hexamethyldisiloxane:
# method ...
Title
0 1
O
Si 1 1.63776
Si 1 1.63776 2 148.48211
C 2 1.87584 1 107.42571 3 198.44... |
I have a question regarding Tkatchenko's new Many Body Dispersion Nonlocal (MBD-NL) (https://arxiv.org/abs/1910.03073) method. Does anyone know if it's a self-consistent method? I read this paper many times but I'm still not sure.
Thanks in advance. |
"Heat of hydrogenation" is a subset of "heat of reaction" which is nothing but the standard enthalpy change ($\Delta H^{\circ}$) in the system as reactants are converted to products. In catalytic hydrogenation, as hydrogen molecules are added to atoms bearing double/triple bonds, the enthalpy change which accompanies t... |
From [Chemistry Libretexts][1]:
>Heat of hydrogenation (symbol: $ΔH_\mathrm{hydro}$) of an alkene is the standard enthalpy of catalytic hydrogenation of an alkene.
**Does the heat of hydrogenation include only the double bonds in an alkene or does it also include other forms of unsaturation, such as rings?**
... |
I have a question regarding Tkatchenko's \[[1](https://arxiv.org/abs/1910.03073)\] new nonlocal many-body dispersion method (MBD-NL). Does anyone know if it's a self-consistent method? I read this paper many times but I'm still not sure.
### References
1. Hermann, J.; Tkatchenko, A. Density-Functional Model for v... |
Is Tkatchenko's MBD-NL method self-consistent? |
>Find the average life of a radio nuclide which decays by parallel paths,
\begin{align}
A &\rightarrow B\\
2A &\rightarrow B,
\end{align}
where the decay constants are $\lambda_1 = \pu{0.018 s-1}$ and $\lambda_2 = \pu{0.001 s-1}$, respectively.
I used the formula
$$\frac{1}{t} = \frac{t_1 t_2}{t_1 + t_2,}$$ ... |
How to find the average half life of radioactive nuclide which undergoes two different decays? |
> But I am getting the correct answer only if I take $\lambda_2$ as $2$ times the given decay constant for the second reaction. Is this because of $\underline{2}A$ on the reactant side instead of $A$?
**Yes.**
----
The way I tend to approach half-life problems is to recast them as the relevant kinetic differen... |
> Suggest a synthetic route to amide C from the alkyl chloride B (reaction mechanisms are _not_ required). Standard reagents and solvents may also be used.
>![N,N,3‐trimethylbutanamide from 1‐chloro‐2‐methylpropane][1]
In this question immediate reaction is to make a grignard reagent with **B** by reacting it wit... |
How to synthesise N,N,3‐trimethylbutanamide from 1‐chloro‐2‐methylpropane? |
Phosgene, $\ce{O=CCl2}$, is a potent toxin and in no way would I consider it a safe or even standard laboratory reagent (at least on an undergraduate level).
Allow me to lead you down the garden path of organic synthesis.
We have a haloalkane. What do we know about such compounds; they have a polarised $\ce{C-X}$... |
If I have aqueous sulfuric acid solution as electrolyte and the anode electrode is made out of copper and the cathode electrode is made out of graphite, what are the two reactions at the respective electrodes and why?
\begin{align}
\text{Anode:} && \ce{Cu &-> Cu^2+ + 2e-}\\
\text{Cathode:}&& \ce{2e- + 2H+ &-> H2 ... |
For the sake of the question, let’s assume that you are provided with two labelled rods of the pure metals $\ce{A}$ and $\ce{B}$ and two unlabelled bottles containing $\pu{1.0 mol dm-3}$ aqueous solution of $\ce{A^m+}$ and the other bottle containing $\pu{1.0 mol dm-3}$ aqueous solution of $\ce{B^n+}$.
I want to fi... |
I have a homework question where I should calculate $R_0$ of an energy transfer between two chromophores. However, I don't understand how my professor arrived at the equation that we should apply (which is important to understand for the exam).
> In a radiationless energy transfer experiment (RET) it was observed t... |
Let's take a look at what you're doing specifically for computing the potential difference. The potentials at the cathode and the anode are all relative to some standard. Importantly, it must be the same standard. Let's refer to this as ground.
$$E_{\mathrm{cathode}} = V_{\mathrm{cathode}} - V_{\mathrm{ground}}$$
$... |
> But I am getting the correct answer only if I take $\lambda_2$ as $2$ times the given decay constant for the second reaction. Is this because of $\underline{2}A$ on the reactant side instead of $A$?
**Yes.**
----
The way I tend to approach half-life problems is to recast them as the relevant kinetic differen... |
How are the parameters of a force field obtained for the bond angle HCH? |
Will this reaction happen? |
Let´s suppose the following reaction:
Eq I: 2 H2O2 —> 2 H2O + O2 with reaction rate ‘v’
Now let´s suppose the same equation with different balance:
Eq II: H2O2 —> H2O + 1/2 O2
I assume that the reaction rate must be the same (‘v’), right? It should not change with stoichometry.
However, depending... |
You don't necessarily need a potential energy curve to fit a force field. I answered a [related question](https://chemistry.stackexchange.com/a/127823/5017) about fitting a force field from quantum calculations.
Let's assume you have a harmonic angle term. You could either do this in terms of the angle bending or th... |
I'm not a chemist and I'm trying to understand a chemistry point from a talk I went to recently. Any help would be much appreciated.
The speaker was talking about +3 (Group 13) elements in the periodic table. He found out that one of them forms MCl4- complexes, where "M" is a +3 element.
He made a comment tha... |
For +3 elements (e.g., Group 13, periodic table), where "M" is an element, why would the formation of MCl4 be more favorable than for +2 elements? |
How do I solve problems where I'm asked for $\Delta H^\circ_f$ and given $\Delta H^\circ_f$ values for equations with the involved elements? For example:
>Find the $\Delta H^\circ_f$ of the following reaction:
$\ce{C + O_{2} -> CO _{2}}$, given:
>$\ce{SrO + CO _{2} -> SrCO_{3}}$ **;** $\Delta H^\circ_f = -234 \... |
It is highly unlikely that there is a non-multicyclic derivative with a stable boat conformation.
There are quite a few imaginable conformations (see what Geoff demonstrates for pyranose sugars in [Conformations of Cyclohexane](https://chemistry.stackexchange.com/q/32970/4945)), but for cyclohexane itself there are ... |
It is well-known that the "chair" conformation of cyclohexane is the most stable of its conformers. But is there any cyclohexane derivative where other notable conformers (boat, half-chair) are the most stable?
My own intuition is that if there are 4 very bulky groups in the 1, 2, 4, 5 positions then the boat confor... |
Can a boat conformer of cyclohexane be stable? |
I'm not a chemist and I'm trying to understand a chemistry point from a talk I went to recently. Any help would be much appreciated.
The speaker was talking about $+3$ (Group 13) elements in the periodic table. He found out that one of them forms $\ce{MCl4-}$ complexes, where $\ce{M}$ is a $+3$ element.
He made... |
For group 13 elements M³⁺, why is the formation of MCl₄⁻ be more favorable than for group 12 elements M²⁺? |
We have a strange problem. We are performing CO2 extraction on cannabis and we are seeing considerable decarboxylation of THCA to THC.
We have high quality temperature sensors at the heat exchangers, the extractor vessels, and the separator. We have not observed any temperature spikes that would explain it.
Vario... |
If entropy is just a measure of the "randomness" or "chaos" of a system, then why does it have specific units. What is the reason behind the units of entropy being J/K?
|
Can someone intuitively explain the reason for the units of entropy (J/K )? |
Entropy isn't "just" a measure of randomness. It is the only physical property that gives the universe a temporal direction, i.e., that provides an "arrow of time".
Also, a "measure of randomness" a crude way to characterize entropy. Rather, the entropy of a system is proportional (through Boltzmann's constant) t... |
Entropy isn't "just" a measure of randomness. It is the only physical property that gives the universe a temporal direction, i.e., that provides an "arrow of time".
Also, a "measure of randomness" a crude way to characterize entropy. Rather, the entropy of a system is proportional (through Boltzmann's constant) t... |
Saytzeff rule says that more alkylated alkene is more stable and the reason is hyper conjugation.
Going by this, 2,3 Dimethyl but-2-ene should be most stable alkene due to 12-alpha hydrogen.
But on drawing hyper conjugative structures of the molecule and a less alkylated alkene, say 2-Methyl propene; there was format... |
I use rainwater in my house for my water supply. I collect the water in plastic lined tanks. Some of my piping at home is copper, and I have blue stains in my shower, because I think the copper from my pipes is being dissolved by the carbonic acid in the rainwater. I'm planning to hang magnesium rods into my rainwat... |
Does Magnesium metal react with carbonic acid? |
For group 13 elements M³⁺, why is the formation of MCl₄⁻ more favorable than for group 12 elements M²⁺? |
I'm not a chemist and I'm trying to understand a chemistry point from a talk I went to recently. Any help would be much appreciated.
The speaker was talking about $+3$ (Group 13) elements in the periodic table. He found out that one of them forms $\ce{MCl4-}$ complexes, where $\ce{M}$ is a $+3$ element.
He made... |
Let´s suppose the following reaction:
Eq I: $$\ce{ 2 H2O2 —> 2 H2O + O2}$$ with reaction rate ‘v’
Now let´s suppose the same equation with different balance:
Eq II: $$\ce{ H2O2 —> H2O + 1/2O2 }$$
I assume that the reaction rate must be the same (‘v’), right? It should not change with stoichometry.
... |
Let’s suppose the following reaction:
$$\ce{ 2 H2O2 —> 2 H2O + O2}\tag{1}$$ with reaction rate $v$
Now let’s suppose the same equation with different balance:
$$\ce{ H2O2 —> H2O + 1/2O2 }\tag{2}$$
I assume that the reaction rate must be the same ($v$), right? It should not change with stoichometry.
How... |
Typically all the problems which I've seen regarding rate of diffusion involve relating the rate of one gas to the other and from there finding either speed of effusion or diffusion or getting the formula weight. However what sort of procedure should be used when it is needed to find the composition of a mixture?
Th... |
Is it possible to determine the composition of a gas mixture from the effusion of a gas through a pinhole? |
I have somewhat established that there is a linear relationship between change in pH of carbonic fizzy drinks over time. I also realise that the pH increases linearly faster for the same carbonated fizzy drink when the temperature of the drink is changed (increased).
Now the problem is, when I graph the relationshi... |
How do I solve problems where I'm asked for $\Delta H^\circ_f$ and given $\Delta H^\circ_f$ values for equations with the involved elements? For example:
>Find the $\Delta H^\circ_f$ of the following reaction:
$\ce{C + O2 -> CO2}$, given:
>$\ce{SrO + CO2 -> SrCO3}$ ; $\Delta H^\circ_f = \pu{-234 kJ}$
>$\ce{2... |
> I assume that the reaction rate must be the same (v), right? It should not change with stoichometry.
No, the reaction rates changes when you double all coefficients. Nothing real changes though (i.e. the rate of disappearing $\ce{H2O2}$ etc.).
You have a similar case with equilibrium constants: when you double ... |
Hydrogen is the most abundant element in the universe and has great properties when reacting with oxygen for use as a fuel. Yet here on Earth, its production is prohibitively expensive, its storage without wastage is almost impossible because its molecules are so small no know substance or material can store it saf... |
### TL;DR:
It is highly unlikely that there is a non-multicyclic derivative with a stable boat conformation.
It needs a lot of convincing and quite bulky groups to destabilise the chair conformation and stable another conformation like the twist-boat.
### Conformations of cyclohexane
There are quite a few imagi... |
Can a boat conformer of cyclohexane be most stable? |
I have some people on youtube stating the steam generating reaction of $$\ce{3H2O2 + 2KMnO4 → 3O2 + 2MnO2 + 2KOH + 2H2O}$$
is catalytic, from where I'm sitting it is purely stoichiometric. Can someone please enlighten me as to why some people would consider this reaction catalytic with the presence of the permangana... |
Learning from the comments and from looking at this video (https://www.youtube.com/watch?v=9S6v-NMMnB4), there are two reactions:
$$\ce{3H2O2 +2KMnO4 -> 3O2 + 2MnO2 + 2K+ + OH- + 2H2O}\tag{1}$$
$$\ce{2H2O2 ->[MnO2] O2 + 2H2O}\tag{2}$$
The first reaction creates the catalyst $\ce{MnO2}$, the second generates ox... |
Learning from the comments and from looking at this video (https://www.youtube.com/watch?v=9S6v-NMMnB4), there are two reactions:
$$\ce{3H2O2 +2KMnO4 -> 3O2 + 2MnO2 + 2K+ + 2OH- + 2H2O}\tag{1}$$
$$\ce{2H2O2 ->[MnO2] O2 + 2H2O}\tag{2}$$
The first reaction creates the catalyst $\ce{MnO2}$, the second generates o... |
Typically all the problems which I've seen regarding rate of diffusion involve relating the rate of one gas to the other and from there finding either speed of effusion or diffusion or getting the formula weight. However what sort of procedure should be used when it is needed to find the composition of a mixture?
Th... |
A document I've been reading states that:
> Both the Maximum Contaminant Level Goal and the Maximum Contaminant Level were set at 2 parts per billion because current technology allows public water suppliers to detect and remove mercury levels that low.
But I know of drinking water test strips that detect 0, 50, 1... |
How is mercury in drinking water detected? |
Typically all the problems which I've seen regarding rate of diffusion involve relating the rate of one gas to the other and from there finding either speed of effusion or diffusion or getting the formula weight. However what sort of procedure should be used when it is needed to find the composition of a mixture?
Th... |
Typically all the problems which I've seen regarding rate of diffusion involve relating the rate of one gas to the other and from there finding either speed of effusion or diffusion or getting the formula weight. However what sort of procedure should be used when it is needed to find the composition of a mixture?
Th... |
For longitudinal relaxation, one would think that magnetic moment obeys this simple relationship $M = M_o(1-2\exp(\frac{t}{T1}))$.
However there is always a point of inflection (?) when magnetisation is zero. Does anyone knows why?
(I take no credit for this image, found it online to illustrate my point)
[![en... |
When I was perusing the works of Schwarz on atomic structure, I came across the unfamiliar term of d-orbital collapse.
He describes it as a variation in energetic sequence from group 1 to 3 elements such that the order changes from 4s<4p<3d in K, 4s<3d<4p in Ca and 3d<4s<4p for Sc and subsequent elements.
He contin... |
What is d-orbital collapse? |
Here are the 2 equations:
\begin{align}
\ce{3Cu + 2NO3- + 8H+ &<=> 3Cu^2+ + 2NO + 4H2O} & E &= 0.62~\mathrm{V}\\
\ce{Cu + 2NO3- + 4H+ &<=> Cu^2+ + 2NO2 + 2H2O}& E &= 0.45~\mathrm{V}\\
\end{align}
The Nernst equation tells us that as we increase the concentration of nitric acid the first equation becomes less s... |
When I was perusing the works of Schwarz on atomic structure, I came across the unfamiliar term of d-orbital collapse.
He describes it as a variation in energetic sequence from group 1 to 3 elements such that the order changes from 4s<4p<3d in K, 4s<3d<4p in Ca and 3d<4s<4p for Sc and subsequent elements.
He contin... |
> if I have 10^-3.83
-3.83 is less than -3.82 and more than -3.84. If we raise 10 to those powers, we get:
$$10^{-3.82} = 0.000151$$
$$10^{-3.84} = 0.000144$$
So the answer is 0.00015 or $\pu{1.5e-4}$
>if I have [...] log(4.32)
$$\log(4.31) = 0.6344$$
$$\log(4.33) = 0.6364$$
So the answer is 0.64.
... |
For longitudinal relaxation, one would think that magnetic moment obeys this simple relationship
$$M = M_0\left[1 - 2\exp\left(\frac{t}{T_1}\right)\right].$$
However there is always a point of inflection (?) when magnetisation is zero. Does anyone knows why?
(I take no credit for this image, found it online to... |
I know as an atom gets bigger the dispersion forces grow with it. But how big does an atom, e.g methanoic acid, to have dispersion forces that outrank dipole-dipole forces? |
How big does an atom need to be to have dispersion forces be greater than other intermolecular forces? |
I think you mean molecules, not atoms. Regardless let's just say you meant molecule and by intermolecular you're really just focusing on Dipole, the answer is- youre comparing apples to oranges. But you don't look at 1 molecule interacting with another rather a whole bunch of molecules interacting simultaneously. At ... |
I'm trying to search for substructures with RDKit.
I would like to search for structure 1 as substructure in other structures. I don't understand why it doesn't find this structure in structures 3 and 5. I assume this is not a bug in RDKit, but more my limited chemistry understanding. Something with aromaticity? Somet... |
There are several examples where the negative inductive effect of a substituent gets increased when a hydrogen atom on that substituent is replaced by an alkyl group.
Some particular examples: $-NR_3+$ > $-NH_3+$, $-OR$ > $-OH$
I don't understand why it should be that way, as an alkyl group shows more positive in... |
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