instruction stringlengths 15 21.8k |
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This is a question that had me puzzled for quite a while. I feel that information is missing.
>A weak acid, $\ce{HA}$, $K_\textrm{a} = \pu{1.0E-4 M}$, is titrated with $\ce{NaOH}$. The concentration of $\ce{NaA}$ at the equivalence point is $\pu{0.010 M}$. What is the $\mathrm{pH}$ at the equivalence point?
a)... |
As it is known benzaldehyde shows cannizaro reaction in which phenyl group is an electron donating group so below reaction (of prop-2-enal) should occur. Major product should be decided by below reaction. Am I true?
[![enter image description here][1]][1]
Note that here acid base reaction cannot occur with concentrat... |
I'm working on a website where I want to provide the pH level of plants! Although i don't even know what this is (I have zero knowledge in chemistry), I have to provide it! What I want to do is provide the pH spectrum on the website so that it would point to the correct pH level of a specific plant.
Let's use the f... |
I realise Chemistry Stack Exchange is not for homework and this will seem incredibly simple to many of you, but I have received no help elsewhere. Last time I tried asking this the question was closed, but I am trying to learn so I can improve. I have attached a photo of a question I’m stuck on. It really shouldn’t b... |
I realise Chemistry Stack Exchange is not for homework and this will seem incredibly simple to many of you, but I have received no help elsewhere. Last time I tried asking this the question was closed, but I am trying to learn so I can improve and be a better chemist. I have attached a photo of a question I’m stuck o... |
I'm working on a website where I want to provide the pH level of plants! Although i don't even know what this is (I have zero knowledge in chemistry), I have to provide it! What I want to do is provide the pH spectrum on the website so that it would point to the correct pH level of a specific plant.
Let's use the f... |
I'm working on a website where I want to provide the pH level of plants! Although i don't even know what this is (I have zero knowledge in chemistry), I have to provide it! What I want to do is provide the pH spectrum on the website so that it would point to the correct pH level of a specific plant.
Let's use the f... |
As it is known benzaldehyde shows cannizaro reaction in which phenyl group is an electron donating group so below reaction (of prop-2-enal) should occur.
Major product in basic medium should be decided by the below reaction(Canizzaro Reaction)and not aldol condensation. Am I correct?
[![Cannizaro Reaction][1]]... |
Is aldol reaction possible for an alpha unsaturated aldehyde? |
Is cannizaro reaction possible for a molecule having Hydrogens attached to sp2 hybridised carbons possible? |
As it is known benzaldehyde shows cannizaro reaction in which phenyl group is an electron donating group so below reaction (of prop-2-enal) should occur.
Major product in basic medium should be decided by the below reaction(Canizzaro Reaction)and not aldol condensation. Am I correct?
[![Cannizaro Reaction][1]]... |
As it is known benzaldehyde shows cannizaro reaction in which phenyl group is an electron donating group so below reaction (of prop-2-enal) should occur.
Major product in basic medium should be decided by the below reaction(Cannizaro Reaction)and not aldol condensation. Am I correct?
 should occur.
Major product in basic medium should be decided by the below reaction (Cannizaro Reaction)and not aldol condensation. Am I correct?
![Cannizaro Rea... |
Is the cannizaro reaction possible for a molecule having hydrogens attached to sp2 hybridised carbons? |
Many manufacturers will sell and advertise emergency preparedness food packs to still taste "great" 25-30 years into the future (or at least maintain a consistent taste over this period). For instance, they will cook eggs, lasagna or vegetables (anything really), then place it into a freeze-drier unit, which eliminates... |
How to maximize shelf-life of freeze-dried food beyond 25 years? Can this exceed 100 years? |
As known benzaldehyde can undergo a cannizaro reaction in which a phenyl group is an electron donating group, so the reaction similar to below (of prop-2-enal) should occur for similar molecules like pent-2,4-dienal.
Major product in basic medium should be decided by the below reaction (Cannizaro Reaction)and not ... |
What grade of stainless steel was the clipper made of? Was it labeled stainless steel, or is this an assumption because it looked shiny or similar to some other corrosion-resistant object (which may itself be stainless steel or not)?
Test with a magnet: if they are non-magnetic, the clippers could be stainless steel... |
I am an IT guy with little knowledge of Chemistry, so please bear with me...
For context: I am working with a system which has a lot of structures, their `.mol` files and some meta data (like mol weights) in a database. Due to an error, some of the meta data was lost and needs to be recalculated. Since there are a l... |
Are aryl halides a type of vinyl halide? From my knowledge, when a Halogen atom is directly bonded to a doubly bonded carbon atom it is a Vinyl halide. When we look at halogen atom directly bonded to a benzene ring we see a similar thing. So are these terms never correlated? Also is Phenylic Halide a term which exists? |
What is the difference between an Aryl Halide and a Vinyl Halide? |
The following question has troubled me for a while.
>For gases that are slightly soluble in water, there is a proportional relationship between the partial
pressure, $P$, and the mole fraction, $x$, of the gas molecules dissolved in water (Henry's law):
>
>$\ce{P = k_H*x}$
>
>A container ($V$ = $570$ $mL$) is f... |
I know fluorine is the most electronegative element but can we humans ever synthesize fluorine in a positive oxidation state like +1? |
Can fluorine ever have a positive oxidation state? |
I was attempting to ascertain the suitability of GCMS to analyze a solvent mixture recovered from a solgel process. The filtered mixture contains heptane and denatured ethanol as major components and small amounts of HMDS and other impurities (various hydrocarbons in the heptane plus methanol in the ethanol). I spiked ... |
Does the appearance of turbidity upon addition of water to an organic solvent mixture imply the presence of nonvolatiles? |
Excuse me if this is the wrong SE community, but my question has mainly to do with chemistry.
I recently collected a sample of what I think is lawsonite, which has the chemical formula $\ce{CaAl_2Si_2O7(OH)_2*H_2O}$.
For context, I am planning to try and use this sample to make a ceramic glaze.
After collecti... |
I know without the nitrogen this molecule would probably be considered a crown ether. What exactly would the nitrogen/oxygen functional groups be named as in this molecule shown below? Any help would be greatly appreciated.
[![Molecule][1]][1]
[1]: https://i.stack.imgur.com/asgsx.pn... |
What functional group is this in this specific molecule? |
My organic chemistry textbook (Clayden, Warren, Greeves) says this: "If we use the $\ce{HBR2}$ reagent $\ce{9-BBN}$, then only the non-cyclic substituent formed in the hydroboration reaction will migrate, selectively giving us the product we want."
Why can't the original substituents of $\ce{9-BBN}$ migrate? It seem... |
I know that plastic are susceptible to UV attack. They create free radicals when put under sunlight even when kept for a short time.
I'd like to know if the photo-damage will stop once it is taken away from the sunlight or will it continue the photo-damage to the plastic. Does the rate becomes very slow because of ... |
For context, I am planning to try and use this sample to make a ceramic glaze.
I recently collected a sample of what I think is lawsonite, which has the chemical formula $\ce{CaAl_2Si_2O7(OH)_2*H_2O}$. After collecting it I calcined it in an electric (oxidation) kiln to around 2016 °F. Assuming that what I collected... |
What is calcined lawsonite? |
My organic chemistry textbook (Clayden, Warren, Greeves) says this:
> If we use the $\ce{HBR2}$ reagent $\ce{9-BBN}$, then only the
> non-cyclic substituent formed in the hydroboration reaction will
> migrate, selectively giving us the product we want.
Why can't the original substituents of $\ce{9-BBN}$ migrat... |
Why 9BBN's rings don't migrate during hydroboration-oxidation? |
> If a monoatomic ideal gas simultaneously expands against a constant external pressure and drops in temperature, how do you find the internal energy change?
>
> Known values are: $T_1$, $T_2$, $p_1$, $p_2$, $p_\text{external}$ and $T_\text{external}$.
Finding the work done by the expansion is easy, but I don't un... |
As known benzaldehyde can undergo a cannizaro reaction in which a phenyl group is an electron donating group, so the reaction similar to below (of prop-2-enal) (cannizaro) should occur for similar molecule 'either having all hydrogen connected to SP2 hybridised carbon (eg: pent2,4dienal) or the carbon which is SP3 hyb... |
>$\ce{R-OH + NaBr + H2SO4->R-Br + NaHSO4 + H2O}$
---
Due to sulphuric acid, the ${\ce-OH}$ group will get protonated and convert into $\ce{-H2O+}$ which is a great leaving group in comparison to the Hydroxyl group. So I thought it would readily form a carbocation and then the $\ce{Br-}$ could attack to form ... |
I just have a question on how you handle polyprotic bases.
Question:
>Show how oxalate ion can be a polyprotic base
My answer:
>1. $$\ce{OOCCOO^{2-} + HOH -> HOOCCOO^{-} + OH ^{-}}$$
>
>2. $$\ce{HOOCCOO^{-} + HOH -> HOOCCOOH + OH-}$$
My question is whether we stop doing the reaction until the oxalate ... |
Methanol-water mix freezing points - clarify contradictory online data > 60% w/w? |
From my understanding, battery provides a driving force to pull electrons from anode, thus the anode become positively charged.
Suppose the anode is copper, the process should be as follows:
$\ce{Cu->Cu^{2+} +2e-}$
However, the copper ions should be dissolved into the electrolyte after this process, and only n... |
Answers on the internet suggest that tetracyanonickelate ($\ce{([Ni(CN)4]^{2-}}$) with square planar structure is diamagnetic because $\ce{CN-}$ is a strong field ligand and causes pairing, but my book says that VBT does not distinguish between strong and weak field ligands. So can anyone explain the logic using VBT? |
March's Advanced Organic Chemistry (8th Ed.), has in its first chapter several tantalizing statements of the following variety;
>Boron has only three valence electrons available to form bonds, hence the valence of 3. Any hybridization model must take this into account.
>If ethene is examined... each carbon has t... |
At very dilute concentrations, the solvating power of water overcomes the natural tendency of surfactant molecules to agglomerate into a separate phase. The shear numerical excess of water molecules just about totally dissociates the bulk surfactant and dissolves it as separate molecules. So a mixture of surfactant and... |
I know that conc $\ce{H2SO4}$ is a dehydrating agent. And the most easiest mechanism for example would be this:
[![mechanism][1]][1]
But I want to know how to find the **extent of dehydration** of it.
I came across this question:
[![question][2]][2]
[1]: https://i.stack.imgur.com/S760X.jpg
[2]: htt... |
I'm in an integrated laboratory course at university that combines all the disciplines of chemistry that we have here. I was instructed to place the yield in the methods section of the report by my professor, but found that to be odd.
Is reporting the yield in the methods section a standard protocol in some paper f... |
Where do we report yields in a research report? |
Its given in my textbook that surface tension of lyophilic/hydrophilic solution is lower than water.
But my intuition says,since in lyophilic solution the interaction between a lyophilic colloid and water molecules would be more than it would be in between two water molecules,the surface tension would increase. But ... |
How lyophilic colloids reduce surface tension? |
[![question][1]][1]
[1]: https://i.stack.imgur.com/d5nYp.jpg
The answer given is (D) but I think (B) should be the answer as the concerned benzylic carbon in option (D) is an unstable tetrahedral complex and it should break. Besides, the medium is acidic so it should catalyse this process.
On generalising... |
**Question**
> Compare the acidic stengths between **benzylammonium ion** and **phenol**.
>
><img src="https://i.stack.imgur.com/hRlPw.png">
I first tried to remove the H+ ion from both of them and tried to compare the relative stabilities of resulting conjugate bases, but I am not sure, which one would be more s... |
[![question][1]][1]
[1]: https://i.stack.imgur.com/d5nYp.jpg
The answer given is (D) but I think (B) should be the answer as the concerned benzylic carbon in option (D) is an unstable tetrahedral complex and it should break. Besides, the medium is acidic so it should catalyse this process.
In generalising,... |
I am an IT guy with little knowledge of Chemistry, so please bear with me...
For context: I am working with a system that has a lot of structures, their `.mol` files and some metadata (like mol weights) in a database. Due to an error, some of the metadata was lost and needs to be recalculated. Since there are a lot ... |
Recently we learnt that there is a depression in the freezing point when a non-volatile solute is added to the solvent. Our teacher explained this phenomenon with a graph where the vapour pressure of the solution and pure solvent intersects with the vapour pressure of the solid solvent. my question is: wouldn't the vap... |
I frequently get confused by the terms cathode and anode when they are used without specifying where they are being used. Electrochemists have to juggle words that are very similar.
In an active cell, the electrode dissolves and positive CAT-ions leave the AN-ode and leave it negative so it can push an electronic cu... |
I just have a question on how you handle polyprotic bases.
Question:
>Show how oxalate ion can be a polyprotic base
My answer:
>![![Monobasic][1]][1]
[![Dibasic][2]][2]
My question is whether we stop doing the reaction until the oxalate ion has no charge or do we keep going on as below:
[![Tribasi... |
From my understanding, a battery provides a driving force to pull electrons from the anode, thus the anode becomes positively charged.
Suppose the anode is copper, the process should be as follows:
$\ce{Cu->Cu^{2+} +2e-}$
However, the copper ions should be dissolved into the electrolyte after this process, and... |
While solving a question set, I found a question with this data table (at $\pu{298K}$):
[![entropy of CO and N2][1]][1]
The first part of the question asked why $\ce{CO}$ has higher $S_\mathrm{spec}$ (spectroscopic entropy) than $S_\mathrm{cal}$ (calorimetric entropy). I know that this is due to the residual entr... |
Why is the spectroscopic entropy of CO higher than that of N2? |
While solving a question set, I found a question with this data table (at $\pu{298K}$):
$$
\begin{array}{lrrr}
\hline
\text{Substance} & T_\mathrm b/\pu{K} & S^⦵_\mathrm{cal}/R & S^⦵_\mathrm{spec}/R \\
\hline
\text{Nitrogen} & 77.35 & 18.3 & 18.30 \\
\text{Carbon monoxide} & 81.61 & 18.6 & 19.22 \\
\hline
\e... |
Why is the spectroscopic entropy of carbon monooxide higher than that of nitrogen? |
I have absorption curves for three species that are nominally the same concentration that I need in order to calculate spectral overlap. Part of that process is dividing the curve through by the concentration as a normalization process. The curves of two species are a factor of 10 lower than the other (not necessarily ... |
The ionization energy of sodium is $5.139eV$. This is the energy *absorbed* when a neutral sodium atom is stripped of its outermost electron. The electron affinity of Chlorine is $3.62eV$. This is the energy *released* when an electron is added to a neutral chlorine atom to form the chlorine anion.
Now suppose we ha... |
Why is a sodium chloride molecule stable? |
When optimizing by DFT medium-sized organic molecules containing aromatic CF3 groups (for example, adducts involving takemoto's catalyst), the frequency calculation on optimized structures have always small negative frequencies involving CF3 groups (small rotations), no matter which program (gaussian or orca), which fu... |
> What are the steps in calculating the photosynthetic rate ($\pu{\mu mole}~ \ce{O2} \pu{m2/ min}$) for a leaf that has an area of $\pu{0.0025 m2}$ and a $\ce{O2}$ evolution
> rate of $0.096~\ce{O2}/\pu{min}$?
To do so , the first step is to convert it to $\mu L$ i.e. $\pu{960 \mu L} ~\ce{O2}/\pu{min}$.
The seco... |
While solving a question set, I found a question with this data table (at $\pu{298K}$):
$$
\begin{array}{lrrr}
\hline
\text{Substance} & T_\mathrm b/\pu{K} & S^⦵_\mathrm{cal}/R & S^⦵_\mathrm{spec}/R \\
\hline
\text{Nitrogen} & 77.35 & 18.3 & 18.30 \\
\text{Carbon monoxide} & 81.61 & 18.6 & 19.22 \\
\hline
\e... |
In the molecular orbital for octahedral metal-ligand complexes, there is an eg orbital and an eg* orbital. When the d orbitals on the metal split, it will fill up some of the eg* orbitals I believe. However, my question is that won't these orbitals cancel out with the eg orbitals and make fewer bonds? For example, $\ce... |
SrSO4 is insoluble in water. Will it be more soluble in a H+ acid solution? I know that if the anion is the conjugate base of a weak acid, it'll be more soluble. Does SO4 2- count as the conjugate base to H2SO4 (strong acid) or HSO4- |
$\ce{SrSO4}$ is insoluble in water. Will it be more soluble in an acid solution? I know that if the anion is the conjugate base of a weak acid, it'll be more soluble. Does $\ce{SO4^2-}$ count as the conjugate base to $\ce{H2SO4}$ (strong acid) or $\ce{HSO4-}$? |
What i knew is that the NMR signal depends on the static magnetic field strength $ B_0 $ (by Boltzmann equation) and its gyromagnetic factor. While the NMR occurs when the RF pulse frequency match the equation:
$$ \nu = \frac{g}{h}\mu_{n}B_{0} $$
but, what about its amplitude? Does the amplitude of the RF pulse affec... |
Is the amplitude of the RF pulse affects the NMR signal? |
Say you take a substituted benzene* and react it with oleum _and_ nitric acid. Would it result in a nitrated ring, a sulphonated ring, or some sort of a combination?
Thinking about it in terms of the first step, the stronger base of $\ce{SO3}$ and $\ce{HNO3}$ seems likelier to get protonated first, making the prefer... |
The ionization energy of sodium is $\pu{5.139eV}$. This is the energy *absorbed* when a neutral sodium atom is stripped of its outermost electron. The electron affinity of chlorine is $\pu{3.62eV}$. This is the energy *released* when an electron is added to a neutral chlorine atom to form the chlorine anion.
Now sup... |
I tried 2 different (among many others) greases with high difference in their base oil viscosity at 40<sup>C</sup>. Their Techincal Data Sheets claim that grease #1 is **9500** mm<sup>2</sup>/s viscous and grease #2 is **1500** mm<sup>2</sup>/s viscous at 40<sup>C</sup>.
Knowing that a viscosity is the *number one f... |
I tried 2 different (among many others) greases with high difference in their base oil viscosity at 40<sup>C</sup>. Their Techincal Data Sheets claim that grease #1 is **9500** mm<sup>2</sup>/s viscous and grease #2 is **1500** mm<sup>2</sup>/s viscous at 40<sup>C</sup>.
After a simple study of the basics of Tribolo... |
With the use of Lewis acid Aluminium Trichloride, which one would have a stronger nucleophilicity? Silyl Ketene Acetal (CAS: 31469-15-5) or a phenyl group? |
silyl ketene acetal vs Benzene, which compound has a higher nucleophilicity? |
Reacting with what electrophile?
In general the silyl ketene acetal will be more reactive, after all the Mukaiyama reaction can be run in Toluene [Mukaiyama Reaction wikipedia page][1]
[1]: https://en.wikipedia.org/wiki/Mukaiyama_aldol_addition |
From all we know only tautomers should get the same InChi key, or, in case of the second block, if there are lots of stereo centers. However these cases are just collisions, they still have different InChi. I have found a class of molecule pairs, with four real-world examples in ChEBI and PubChem, where both web input ... |
different molecule (cis/trans), same InChi? |
My teacher was teaching me the boiling point composition curve for fractional distillation and in the class notes he gave the following diagram (I have given below). It says that the residue starts accumulating at the point on the vaprous line just above the liquidus line (above $χ_{A},χ_{B}$). Now that $χ_{A},χ_{B}$ d... |
Where does the residue accumulate in the boiling point composition curve? |
In the lab E stilbene can be crystallized from Z stillbene and the side product (TPPO) by using absolute ethanol. My question is why? E stilbene and Z stilbene are isomers, why do they differ in polarity? they both should be non-polar, why is Z stilbene soluble in ethanol but not E stilbene? Also why is Z stilbene more... |
E Stillbene vs Z Stillbene polarity? |
Does the amplitude of the RF pulse affect the NMR signal? |
What I know is that the NMR signal depends on the static magnetic field strength $ B_0 $ (by Boltzmann equation) and its gyromagnetic factor. While the NMR occurs when the RF pulse frequency match the equation:
$$ \nu = \frac{g}{h}\mu_{n}B_{0} $$
but, what about its amplitude? Does the amplitude of the RF pulse affec... |
I know that the NMR signal depends on the static magnetic field strength $ B_0 $ (by Boltzmann equation) and its gyromagnetic factor. While NMR occurs when the RF pulse frequency matches the equation:
$$ \nu = \frac{g}{h}\mu_{n}B_{0} $$
what about its amplitude? Does the amplitude of the RF pulse affect the NMR signa... |
In the van't Hoff equation, why do we say that the change in enthalpy at standard pressure is constant? My book derives the equation for a mixture of ideal gases reacting with each other. The proof itself is good, until the authors declare that the equation says that the graph of ln K with 1/T, where K is the equilibri... |
### Problem
> It is believed that non-stoichiometric compound Fe0.93 O forms by doping of Fe3+ ions in FeO crystal by replacement of Fe2+. Calculate the number of cationic vacancies if all of the Fe2+ ions are replaced by Si4+ ions in 0.1 mole of Fe0.93 O. Express your answer as a multiple of Avogadro's Number.
#... |
In the van't Hoff equation, why do we say that the change in enthalpy at standard pressure is constant? My book derives the equation for a mixture of ideal gases reacting with each other. The proof itself is good, until the authors declare that the equation says that the graph of ln K with 1/T, where K is the equilibri... |
From all we know only tautomers should get the same InChi key, or, in case of the second block, if there are lots of stereo centers. However these cases are just collisions, they still have different InChi. I have found a class of molecule pairs, with four real-world examples in ChEBI and PubChem, where both web input ... |
Can geometric isomers have same InChi? |
According to the IUPAC rules of nomenclature, alkenes have higher priority over rings but what if the ring also contains a double or a triple bond?
For eg:-
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/f82bd.jpg
Is this going to be named as 1-(2-Chlorocycloprop-2-enoxy) propene o... |
Which has higher priority between unsaturated ring and unsaturated chain in the nomenclature of organic compounds? |
According to the IUPAC rules of nomenclature, alkenes have higher priority over rings but what if the ring also contains a double or a triple bond?
For eg:
[![Organic compound][1]][1]
Is this compound going to be named as 1-(2-chlorocycloprop-2-enoxy)propene or 1-chloro-3-propenoxycyclopropene?
[1]: h... |
In the van't Hoff equation, why do we say that the change in enthalpy at standard pressure is constant? My book derives the equation for a mixture of ideal gases reacting with each other. The proof itself is good, until the authors declare that the equation says that the graph of $\ln K$ with $\frac{1}{T}$, where $K$ i... |
In my textbook it is written that $ΔV_{mix} = 0$ for ideal solutions i.e. $V_{solution} = V_{A} + V_{B}$. But why is this true? There is literally no explanation in my textbook as to why this is true. I am so confused. Please can someone explain it rigorously. Please help. |
Why is change in volume of the solution zero in case of an ideal solution? |
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