instruction stringlengths 15 21.8k |
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Why does zinc sulfide have to be doped with silver to phosphoresce? |
The rate equation is $$\ln[A] = \ln[A]_0 − kt$$ So, $a-x=[A]$. Don't subtract the next value. Put it as it is. $[A]=238 \text{ where } t=10 \text{ and } [A]=227 \text{ where } t=20$. Using the above mentioned equation: $$\ln[A] = \ln[A]_0 − kt$$ Calculate the value of $\mathrm{ln[A]_0}$ by eliminating k. Thereafter, y... |
> In a solution of Fe$^3+$ the concentration was measured to be:
$$\begin{array}{c|c|c|}
& \text{t/min} & \text{[Fe3+]/µM} \\ \hline
\ & 10\ & 238\\ \hline
\ & 20 & 227\\ \hline
\ & 40\ & 206\\ \hline
\ & 60\ &187 \\ \hline
\ & 80\ &169\\ \hline
\ & 100\ &154 \\ \hline
\end{array}$$
>The decrease in Fe$^3+$... |
The rate equation is $$\ln[\ce{Fe^{3+}}] = \ln[\ce{Fe^{3+}}]_0 − kt$$ So, $a-x=[A]$. Don't subtract the next value. Put it as it is. $[\ce{Fe^{3+}}]=238 \text{ where } t=10 \text{ and } [\ce{Fe^{3+}}]=227 \text{ where } t=20$. Using the above mentioned equation: $$\ln[A] = \ln[A]_0 − kt$$ Calculate the value of $\math... |
Benzyl Carbocation could form multiple conjugation, then why isn't that stabler? In Methyl methoxy carbocation, Oxygen donates the lone pairs but so does the double bond in the benzyl Carbocation. |
Among Benzyl carbocation (Ph-CH2+) and Methyl methoxy carbocation (CH3-O-CH2+), why is the latter more stable? |
I'm reading something at the moment where they state:
>This reagent has enhanced basicity as it benefits from the high kinetic basicity of alkoxides compared to alkyls.
This is in the context of organometallics so we're talking about a negatively charged alkoxide ligand versus a negatively charged alkyl ligand.
... |
> In a solution of $\ce{Fe^3+}$ the concentration was measured to be:
$$\begin{array}{c|c|c|}
t/\pu{min} & \ce{[Fe^3+]}/\pu{\mu M} \\ \hline
10\ & 238\\
20 & 227\\
40\ & 206\\
60\ & 187 \\
80\ & 169\\
100\ & 154 \\
\hline
\end{array}$$
>The decrease in $\ce{Fe^3+}$ concentration is due to the hydrolysis... |
> In a solution of $\ce{Fe^3+}$ the concentration was measured to be:
$$\begin{array}{c|c}
t/\pu{min} & \ce{[Fe^3+]}/\pu{\mu M} \\ \hline
10\ & 238\\
20 & 227\\
40\ & 206\\
60\ & 187 \\
80\ & 169\\
100\ & 154 \\
\hline
\end{array}$$
>The decrease in $\ce{Fe^3+}$ concentration is due to the hydrolysis of... |
Can you please give me the proof of the following equation?
$$T_{i}= \frac{2a}{Rb}$$
where $T_{i}$ is inversion temperature for a Joule-Thomson experiment on a van der Waals gas. And why is it twice of that of Boyle's temperature? |
I want to know how bonding electrons behave when they have to cover for both atoms. They can spin around only one atom right? If so then what happens when covalent bond forms. Let's say we have 2 covalent bond between two atoms (for example: C=O), so they have 2 pair of shared electrons.
Now my question is how they ... |
How bond electrons covers both atoms in covalent bond? |
I think you can look at this entirely from the perspective of entropy (forget about the Gibbs free energy for a moment). You can divide the universe into two parts, the system and its surroundings.
When a change happens in your system, and some heat is exchanged with the surroundings then the change in entropy of th... |
Why is the ester carbonyl peak in benzocaine IR spectrum so low? |
Why is it that heat and work are path functions but their sum i.e. internal energy is a state function? How is it even possible?
$ΔU=q+W$ |
I haven’t really found a clear answer.
Enthalpy is measured as the sum of internal energy (kinetic and potential energy) and pressure times value. However, I don’t really see the value of measuring enthalpy, so why is it even mentioned? Aren’t we more concerned with changes in enthalpy, like enthalpy of vaporization,... |
Why is addition to acid chloride favoured over SN2 at the carbon even though it has a Beta-carbonyl? |
I haven’t really found a clear answer.
Enthalpy is measured as the sum of internal energy (kinetic and potential energy) and pressure times volume. However, I don’t really see the value of measuring enthalpy, so why is it even mentioned? Aren’t we more concerned with changes in enthalpy, like enthalpy of vaporizati... |
Now, I am doing a science worksheet and I came across an opportunity to write either "decoxide" or "decaoxide". Since the latter sounds wrong out loud, I decided to google it before I wrote it out, just to be sure. What I got instead, once I had filtered out all of the references to phosphorus or tetraphosphorus, was a... |
Decoxide vs decaoxide? |
I want to know how bonding electrons behave when they have to cover for both atoms. They can spin around only one atom right? If so then what happens when covalent bond forms.
Let's say we have 2 covalent bond between two atoms (for example: $\ce{C=O}$), so they have 2 pair of shared electrons.
Now my question is... |
I want to know how bonding electrons behave when they have to cover for both atoms. Electrons can spin around only one atom right? If so, then what happens when a covalent bond forms?
Let's say we have two covalent bonds between two atoms (for example: $\ce{C=O}$), so they have two pairs of shared electrons.
Sinc... |
How do bond electrons covers both atoms in covalent bond? |
Suppose the pressure is $1$ $atm$ and we put water (at $25°C$)in an open container. After some time the water will disappear as the eater evaporates out. Here's my doubt : We know that water at $25°C$ and $1$ $atm$ has not reached has a vapour pressure. And this vapour pressure is obviously less than the atmosphere pre... |
How does evaporation even possible? |
Ester hydrolysis occurs in basic medium and this is the medium which is usually preferred for the same. But I am facing a very fundamental doubt and not able to understand the reason.
Ester Hydrolysis goes like this:
> $\ce{RCOOR' + OH- <=> RCOOH + OR'-}$
Now according to me $\ce{OR'-}$ should be a better bas... |
Electrical conductivity decreases as an acid becomes more concentrated because more ions form pairs. However, does that affect the speed of reaction of the acid as there is a smaller concentration of Hydrogen ions? |
More ions form pairs when concentration of acid increases, does that decrease the speed of reaction? |
I have been asked to determine the nature of the product for the following reaction:
[![Oxidation reaction][1]][1]
And as I recognized this reaction to be a case of *syn-dihydroxylation*, my obvious response was that the product formed will be *meso*.
But, in the solution to the problem, it says it makes a r... |
So it is written in our text that electric susceptibility is related to the molecular behaviour of various substances, but it doesnt explore it.
We know that the capacitance increases with water as a dielectric as opposed to oil, and many other non-polar substances, We can easily relate this to their dielectric cons... |
Is there a relation between polarity of molecules and their electric susceptibility? |
I have been asked to determine the nature of the product for the following reaction:
[![Oxidation reaction][1]][1]
And as I recognized this reaction to be a case of *syn-dihydroxylation*, my obvious response was that the product formed will be *meso*.
But, in the solution to the problem, it says it makes a r... |
How is this Cope Reaction forming Ethene as major product? |
**Enthalpy vs ∆Enthalpy**
We know that enthalpy represents the energy of a system. So, now think about it? Measuring the energy of a system? Consider all the changes and influences a system is under. This makes it really difficult (we could say impossible) to calculate the enthalpy of a system.
But we do know one... |
I am having trouble conceptualizing endergonic reactions and their difference from endothermic reactions. An endergonic reaction is one that has a positive Gibbs free energy change, such that energy is taken in for the reaction to take place; in biological systems the very exergonic breakdown of ATP is a major source. ... |
I think you can look at this entirely from the perspective of entropy (forget about the Gibbs free energy for a moment). You can divide the universe into two parts, the system and its surroundings.
When a change happens in your system, and some heat is exchanged with the surroundings then the change in entropy of th... |
I'm studing the following version of iodine clock reaction, in which, [H2O2]0>[ascorbic acid]0
I- + H2O2 --> I2
I2 + ascorbic acid--> I- + ....
[induction period] (when [ascorbic acid]=0]
I2 + I-->I3-
I3- + starch --> blue complex
In the first moment I thought that, due to the abrupt occurence of the ... |
Does the rate reaction of clock reaction increase over time? |
I think you can look at this entirely from the perspective of entropy (forget about the Gibbs free energy for a moment). You can divide the universe into two parts, the system and its surroundings.
When a change happens in your system, and some heat is exchanged with the surroundings then the change in entropy of th... |
I think you can look at this entirely from the perspective of entropy (forget about the Gibbs free energy for a moment). You can divide the universe into two parts, the system and its surroundings.
When a change happens in your system, and some heat is exchanged with the surroundings then the change in entropy of th... |
I'm studing the following version of iodine clock reaction, in which, $[\ce{H_2O_2}]_0$>[ascorbic acid]$_0$
$\ce{I^-} + \ce{H_2O_2}$ --> $\ce{I_2}$
$\ce{I_2}$ + ascorbic acid --> $\ce{I^-}$ + ....
[induction period] (when [ascorbic acid]=0]
$\ce{I_2} + \ce{I^-}$-->$\ce{I_3^-}$
$\ce{I_3^-}$ + starch --> b... |
The rate equation is $$\ln[\ce{Fe^{3+}}] = \ln[\ce{Fe^{3+}}]_0 − kt$$ So, $a-x=[A]$. Don't subtract the next value. Put it as it is. That's just for your understanding, however. Don't try to use the integrated rate form to plot the graph. $[\ce{Fe^{3+}}]=238 \text{ where } t=10 \text{ and } [\ce{Fe^{3+}}]=227 \text{ w... |
I'm studing the following version of iodine clock reaction, in which, $[\ce{H_2O_2}]_0$ > [ascorbic acid]$_0$
$$\ce{I^- + H_2O_2 -> I_2}$$
$$\ce{I2 + ascorbic acid -> I- +?}$$
When the concentration of ascorbic acid is zero, also known as induction period,
$$\ce{I2 + I- -> I3-}$$
$$\ce{I3- + starch -> blue... |
In the following derivation, I just calculated the absolute internal energy of an ideal gas as a function of its temperature. But my teacher said that we can never calculate the absolute internal energy in thermodynamics. Then how did I do it?in an open container. After some time the water will disappear as the water evaporates. Here's my doubt : We know that water at $25°C$ and $1$ $atm$ has a vapour pressure. And this vapour pressure is obviously less than the atmospheric pressure or external p... |
Suppose the pressure is 1 atm and we put water (at 25 °C) in an open container. After some time the water will disappear as the water evaporates. We know that water at 25 °C and 1 atm has a vapour pressure. And this vapour pressure is obviously less than the atmospheric pressure or external pressure as no boiling is oc... |
I want to determine rate of Fenton reaction with different concentration of $\ce{Fe^2+}$. These are some questions that I have encountered:
1. How long does it usually take for the reaction to complete?
2. What concentration of $\ce{Fe^2+}$ is usually used for the reaction?
3. I am planning to use titration... |
My textbooks have explained why Enthalpy, Entropy, Internal Energy, Gibbs Free Energy are state functions or path functions only intuitively and with examples. But that never fully satisfied me. Is there any mathematical way to prove whether a given function is a state function or path function? |
Is there a mathematical and rigorous way to prove whether a given function is a state function or a path function? |
Here is a question which was given to me:
> Which of the following will give strength of acid?<br>A) pH<br>B) Normality<br>C) Degree of Dissociation<br>D) Dissociation Constant
And the answer was given as: $C$ and $D$
Now what I fail to understand is that, if pH is not considered as a metric to assess the stre... |
Which of the following will give the strength of an acid? |
So it is written in our text that electric susceptibility ($χe$) (the response of say water molecules in the presence of an external electric field) is related to the molecular behaviour of various substances, but it doesnt explore it, and says its out of scope for me. When I tried to find the related equations, I coul... |
### Problem
> Which of the following will give strength of acid?
>
> A) pH
> B) Normality
> C) Degree of dissociation
> D) Dissociation constant
### Answer
>! C, D
### Question
If pH is not considered as a metric to assess the strength of an acid because it depends on dilution (even strong ac... |
Why is degree of dissociation used to estimate strength of an acid? |
when dealing with waste water and the total values of P, N, C are given in ppm units, what molecular weight is used for converting from ppm to molar?
for Example- what will be 12 ppm of P(T) in Molar unit? |
when dealing with waste water and the total values of P, N, C are given in ppm units, what molecular weight is used for converting from ppm to molar?
[![enter image description here][1]][1]
for Example- what will be 12 ppm of P(T) in Molar unit?
[1]: https://i.stack.imgur.com/iOUFL.png |
**1 mole each of A and B were mixed to obtain an ideal solution of which one mole went to the vapour phase at equilibrium. If P°(A) = 100 torr and P°(B)=900 torr, Then Ps would be?**
for the above question, i first calculated Vapour pressure of A and B which came out to be 50 torr and 450 torr respectively (using P°... |
In group 14, the double bond becomes increasingly weaker down the group. Our lecturer told us that many distannenes ($\ce{>Sn=Sn<}$) and almost all diplumbenes ($\ce{>Pb=Pb<}$) dissociate into stannylene ($\ce{R2Sn:}$) and plymbylenes ($\ce{R2Pb:}$) when dissolved in hydrocarbon solution.
The weak nature of $\ce{Sn=... |
HCQ does show [antiviral properties in vitro][1], but, in vivo (in humans), when taken after an initial dose of 800mg for 4 days at 600 mg/day, it was not found to prevent COVID-19 in high-risk exposure settings. Thus, it didn't stop people from getting SARS-CoV-2 infection followed by onset of symptoms/severity.
... |
>**Question:
1 mole each of A and B were mixed to obtain an ideal solution of which one mole went to the vapour phase at equilibrium.
If $P°_A = 100 torr$ and $P°_B = 900 torr$, then $P_S$ would be?**
For the above question, I first calculated vapour pressure of A and B which came out to be $50 torr$ and $450 torr... |
What makes sea salt coarser than other salt?
I have tried checking online but no one seems to discuss this. It seems that the grain of sea salt is larger, but I don't understand since the salt is dissolved in the sea water so how does it become coarse. |
Why is sea salt coarse? |
The method of production of sea salt usually involves bulk evaporation of sea water. This allows the salt to crystallise and due to it's bigger size it is sold without much processing. On the other hand, the table salt has much smaller size and is processed a lot more than we could assume before it is sold.
This could... |
I added stearic acid to hot vegetable oil and saw it turned to a sludgy, slush material in about 1.5 hours. Is there any other natural additive that I can add to make it more solid?
I'm currently trying soy wax + stearic acid.
Are there any other natural alternatives?
p.s I'm not sure I posted in the correc... |
I added stearic acid to hot vegetable oil and saw it turned to a sludgy, slush material in about 1.5 hours. Is there any other natural additive that I can add to make it more solid in the same amount of time?
I'm currently trying soy wax + stearic acid.
Are there any other natural alternatives?
p.s I'm not ... |
*CAS: 119-36-8* \
I ran a neat sample of methyl salicylate on the GC-MS and used m/z 120 as the quantifier and m/z 92 and 152 as qualifiers. Below is the SIM spectrum for these ions, with two distinct peaks. Both peaks are identified by the NIST spectrum database as that of methyl salicylate. Considering this is a nea... |
Why do I see two peaks for methyl salicylate in my GC-MS spectrum? |
With the help of HVZ reaction, we can get alpha-chloro or alpha-bromo carboxylic acid.
[![enter image description here][1]][1]
But can we make alpha-iodocarboxylic acid with the help of HVZ reaction? I could not find any reference of HVZ reaction forming alpha-iodocarboxylic acid.
Though $\ce{PI3}$ is much les... |
Can we use phosphorous triiodide in Hell-Volhard-Zelinsky reaction? |
**Context**: I was casually looking through some old questions when I found [this question][1]. The OP wanted a compound that has all the hydrates ranging from monohydrate to decahydrate. I found [chromium(III) sulfate][2] [$\ce{Cr2(SO4)3.x(H2O)}$ where x=0-18] to be suitable. But, the actual formula of the compound is... |
> **$3.12$** A reaction $\ce{A + B ->C}$, follows first order kinetics with respect to each reactant, with an overall rate constant $k=\pu{2.0 x 10^{-3} M-1s-1}$, the initial concentrations of A and B are $\pu{0.10 M}$ and $\pu{6.93 M}$. respectively. Given $\ln 2 = 0.693$, choose the correct statement(s).
>
> (A) Th... |
I have been asked to find the major product of the following reaction:
[![enter image description here][1]][1]
This is my thought process: the lone pairs of the oxygen atom connected to $\ce{-Et}$ are less delocalised than the other oxygen atom. So, that will abstract the $\ce{H^+}$ from $\ce{HI}$ leaving behind $... |
Why is the ether linkage breaking here? |
This feels like cheating, since andselisk did all the hard work already and could have provided you with the [answer][1], but I would think
$$\ce{Na48[H_xMo368O1032(H2O)240(SO4)48] · \text{ca.}~1000 H2O}$$
is a good candidate for the largest inorganic hydrate. Note the "circa" 1000 waters. Unfortunately I don't ... |
Why does the malleability and ductility of interstitial carbides decrease? I read the following in my book but I am not able to find what is the reason for the same. Why does this happen? Is it to do with the change in lattice properties? |
Why does malleability and ductility of interstitial carbides decrease? |
> 1. How would you deal with a user who produced a steady stream of valuable answers, but tends to generate a large number of arguments/flags from comments?
Presumably if an unsuccessful attempt had already been made to convince the user to alter their behavior, I would follow up as necessary according to [the stand... |
I don't understand how a salt bridge work **exactly**: what happens inside it and how it affect the cell's lifetime.
**I have already read:**
https://chemistry.stackexchange.com/questions/93883/salt-bridges-porous-disks
https://chemistry.stackexchange.com/questions/8292/salinic-bridges-in-voltaic-cells
http... |
What happens inside salt bridges? |
In Armstrong's Mixture, mixing those two chemicals results in a friction sensitive explosive which produces a loud bang. According to wikipedia, it is made by adding a strong oxidizer to red phosphorus, but what is the explanation as to why it reacts so strongly? Thank you |
Why does Red Phosphorus react so violently with an oxidizer like Potassium Chlorate? |
let's see the resoance forms of benzyl carbocation and methoxy carbocation:
-Benzyl carbocation:
[![enter image description here][1]][1]
You are right, benzyl carbocation have multiple ressonance forms which means that It must be very stable. In fact, benzyl carbocation is one of the most stable carbocations.
... |
**Context**: I was casually looking through some old questions when I found [this question][1]. The OP wanted a compound that has all the hydrates ranging from monohydrate to decahydrate. I found [chromium(III) sulfate][2] [$\ce{Cr2(SO4)3.$x$(H2O)}$ where $x=0,\ldots,18$] to be suitable. But, the actual formula of the ... |
>**Question:
1 mole each of A and B were mixed to obtain an ideal solution of which one mole went to the vapour phase at equilibrium.
If $P°_\mathrm{A} = \pu{100 torr}$ and $P°_\mathrm{B} = \pu{900 torr}$, then $P_\mathrm{S}$ would be?**
For the above question, I first calculated vapour pressure of A and B which c... |
Why does the malleability and ductility of interstitial carbides decrease? I read the following in my book but I am not able to find what is the reason for the same. Why does this happen? Is it to do with the change in lattice properties?
I read this in JD Lee (adapted version by Sudarshan Guha), it stated after a s... |
Why does the malleability and ductility of interstitial carbides decrease? I read the following in my book, but I am not able to find what is the reason for the same. Why does this happen? Is it to do with the change in lattice properties?
I read this in JD Lee (adapted version by Sudarshan Guha), it stated after a ... |
The reaction of a terminal alkyne with $\ce{NaNH2}$ leads to loss of Hydrogen ion from the terminal carbon.
But what will happen if the alkyne is a non-terminal one, I am not able to think that out. How would $\ce{NH2-}$ attack then? Would any reaction even happen?
As an example what would happen in case of this fo... |
The reaction of a terminal alkyne with $\ce{NaNH2}$ leads to the loss of hydrogen ion from the terminal carbon.
But what will happen if the alkyne is a non-terminal one? How would $\ce{NH2-}$ attack then? Would any reaction even happen?
As an example, what would happen in case of this following reaction:
$$\ce... |
How would sodium amide react with a non-terminal alkyne? |
The catalytic efficiency of an enzyme is given by $k_{cat}/k_M$ where $k_{cat}$ is the turnover number, or the number of molecules that can be produced per second per active site of an enzyme.
$k_{M}$ is a measure of the affinity of the enzyme with the substrate, or the likelihood of binding.
My question is, why... |
Why use Km in catalytic efficency? |
We know the maximum covalent is at least 3 with such species as $\ce{H3O+}$. Also the pyrylium ion (https://en.m.wikipedia.org/wiki/Pyrylium_salt) has an oxygen covalency of 3 by forming a pi bond for the third bond.
Can we get 4-coordination? As mentioned by @Rob, yes. @Rob's comment states that basic berylliu... |
[![physical_biochem][1]][1]
[1]: https://i.stack.imgur.com/iQuuP.jpg
How do you calculate HOMO and LUMO given that 20 pi electrons exist? Writing the electron configuration of the ground state molecule doesn’t seem to work here (too lengthy).... |
I have read the definition of vapour on Wikipedia, but I don't seem to have a clear idea about how different is a vapour from a gas. I know what it means when it says, "gas at a temperature lower than its critical temperature".
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/ZLQAl.png
... |
What made Scientists Coin the term "Vapour" when had "Gas"? |
I tried one experiment. I started with ordinal yellow zinc screws.
The screws were sumberged in bath of two parts of $4.7\%$ solution of $\ce{NaClO}$ and one part $\ce{NaOH}$. The screws turned silverish in color. Then, I submerge them into vinegar. Vinegar turned them black. I am now wondering what actually happen... |
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