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How strong are molecular bonds in layman's terms? |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> exothermic reaction: "A reaction for which the overall standard
> enthalpy change $Δ... |
I am trying to investigate the relationship between the solubility of aspirin in water with relationship to some variable. In my investigation, I seem to be stuck with the calculation of finding the solubility. Since, reacting aspirin with aqueous NaOH effects solubility, one possible direction I considered taking is i... |
How to get the SMILES of all compounds on chempub? |
> This doesn't make any sense to me, is there any good reason for this discrepancy?
Provided you remember the convention you are using it shouldn't matter. You could argue that either way "makes sense". If you draw it the way that you suggest is logical, then you are right, the low energy configuration will see the ... |
Does salt hydrolysis takes place in buffer solution? |
How to get the SMILES of all compounds on PubChem? |
I want to produce Calcium Chloride container Desiccant for Food and Textiles related items.
I have this specs of Calcium Chloride and i have PP Non Woven Bags for its packaging. I want to know just to add this specs Calcium Chloride in bags to ... |
I am interested in calculating the transition dipole moment (TDM) from the information from two wavefunctions of different states. This is somewhat similar to calculating the molecular dipole moment which was previously answered here:
[How to calculate molecular dipole moment from a known wavefunction?](https://chem... |
I am trying to investigate the relationship between the solubility of aspirin in water with the relationship to some variables. In my investigation, I seem to be stuck with the calculation of finding the solubility. Since reacting aspirin with aqueous NaOH affects solubility, one possible direction I considered taking ... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
What is the reason for IUPAC's definitions of exo- and endothermic reaction to be disconnected from the direction of heat flow? |
The following question was given in my FIITJEE study material:
> $$\ce{Benzene + (conc.) HNO_3 + HNO_2 ->}$$ Final product of the reaction is:
[![enter image description here][1]][1],
[![enter image description here][2]][2],
[![enter image description here][3]][3],
[![enter image description here][4]][4]
<h... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
Why are IUPAC's definitions of exo- and endothermic disconnected from the direction of heat flow? |
We study that when we connect a wire between the terminals of a battery ,an electric field in established between terminals due to potential difference .Is the potential difference result of accumulated charges on terminals. In other words when an electrode is put in the solution like Zn in ZnSO4 will Zn electrode ... |
In a galvanic cell,do charges accumulate on electrodes 1st (then redox occur) which produce E in the wire when we connect between electrodes? |
I am using charcoal toothpaste for an actor to spit bile on stage during a show. The paste is not the correct state for our needs.
I know that you can freeze toothpaste and it becomes "more" solid and stable at room temperature but still not stable enough.
What organic edible compound(s) could I add to the toothpast... |
The following question was asked on myPAT website:
> [![enter image description here][1]][1]
> [![enter image description here][2]][2]
<hr />
I started with the solution by counting the __Hyper-conjugative__ structures available with each alkene. Based on this concept _only_, order is:
I > II = III > IV
... |
Let us assume we deal with ideal systems without interactions.
The gel phase and the supernatant solution phase are in thermodynamic equilibrium. The supernatant solution shall consist of different ion species $i$.
The gel is in free swelling equilibrium and the total chemical potential of each ion species $i$ is ... |
Is pH in a charged Gel and its supernatant solution constant? |
Who said boron is a base? The fact that it does not weaken or neutralize most acids ought to tip you off that it isn't.
Boron is slowly oxidized when powdered and exposed to nitric acid (see [here](https://www.webelements.com/boron/chemistry.html)), and we may call it "basic" by virtue of the products being much we... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
30 ml. Magnesium Hydroxide USP is added to 2 l. carbonated water to make magnesium bicarbonate to be used as a highly bio-absorbable Mg dietary supplement. I'm told the result is 90 mg. elemental Mg per each 4 oz. of this "Magnesium Water."
If one gram of ascorbic acid is added to a small amount of this Mg solution ... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
So my book says that the batteries we have considered so far( Daniell cells) are low life span, because they reach equilibrium too fast. In the next paragraph, it says they are also made by irreversible reactions and we call them primary battery. How can one reaction reach equilibrium without being reversible? |
Is pH in a charged hydrogel and its supernatant solution constant? |
WHY do we call the negative end "cathode" and positive end "anode" in [isoelectric focusing][1] but the positive end the "cathode" and negative end the "anode" in [galvanic cells][2]? Who was responsible for this naming system and how can we change it?
[1]: https://en.wikipedia.org/wiki/Isoelectric_focusing
[... |
What dictates cathode vs anode nomenclature use? |
> Who was responsible for this naming system and how can we change it?
Michael Faraday was responsible for the terms anode and cathode more than hundred years ago.
All the confusion regarding the nomenclature will vanish if you do not associate electrostatic signs with these two terms. One should identify the ele... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
The following question was given in my FIITJEE study material:
> $$\ce{Benzene + \text{conc.} HNO_3 + HNO_2 ->}$$ Final product of the reaction is:
[![enter image description here][1]][1],
[![enter image description here][2]][2],
[![enter image description here][3]][3],
[![enter image description here][4]][4]
... |
I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow.
Specifically, here are IUPAC's *Gold Book* definitions:
> **exothermic reaction** (https://doi.org/10.1351/goldbook.E02269, Last updated: Februa... |
The following question was asked on myPAT website:
> [![enter image description here][1]][1]
> [![enter image description here][2]][2]
<hr />
I started with the solution by counting the __Hyper-conjugative__ structures available to each alkene. Based on this concept _only_, order is:
I > II = III > IV
... |
$E°_{cell}$ is the EMF of the cell for a reaction with respect to standard hydrogen electrode(SHE). So why don't we represent $E°_{cell}$ or $E_{cell}$ by $\Delta$ symbol in the same manner in which we represent $∆H°,∆G°,∆S°, etc$ as their values with respect to initial absolute zero temperature? |
Why is $E°_{cell}$ not $\Delta E°_{cell}$? |
WHY do we call the negative end "cathode" and positive end "anode" in [isoelectric focusing][1] but the positive end the "cathode" and negative end the "anode" in [galvanic cells][2]? in fact why do we use this terminology at all for IEF?
[1]: https://en.wikipedia.org/wiki/Isoelectric_focusing
[2]: https://en.w... |
As noted in [this question][1], magnesium carbonate is often used by rock climbers to help mitigate the effect of sweating whilst climbing. While this is not a major issue on artificial walls, the residue left by climbers on natural rock is unsightly and has lead to climbing bans or adverse public perceptions.
[![en... |
How to achieve lowdin transformation? |
I use Gaussian 09 to obtain the Hamiltonian and overlap matrices, $H_0$ and $S_0,$ where the B3LYP functional and the 6-31G basis set are adopted. Then how to
transform the system to an orthogonal basis using Löwdin transformation?
$$
\begin{align}
H_1 &= S_0^{-\frac{1}{2}}H_0S_0^{-\frac{1}{2}} \\
H &= U^\dagger... |
How to achieve Löwdin transformation? |
I will assume that by "a single sheet of graphite" you mean [graphene][1].
The link in the comments to the wikipedia page on [orders of magnitude of different forces][2], provided by @Alchimista in the comments, is helpful in getting a perspective on at least a few of your questions. Two useful reference values are... |
The following question was given in my FIITJEE study material:
> $$\ce{Benzene + \text{conc.} HNO_3 + HNO_2 ->}$$ Final product of the reaction is:
[![enter image description here][1]][1],
[![enter image description here][2]][2],
[![enter image description here][3]][3],
[![enter image description here][4]][4]
... |
I know that sulfuric acid is considered a strong acid, and the dissociation of its first $\ce{H+}$ ion is complete and of its second $\ce{H+}$ ion is partial.
Phosphoric acid is weak and all three of its $\ce{H+}$ ions dissociate partially.
I just wanted to clarify: are dibasic and tribasic acids considered stron... |
thanks for taking the time. I am physicist doing experiments in which I need certain Ions (at the moment, Ru(II)) in solution. I have no chemical training excepting what I'm learning right now. What I need is a research strategy on how to find which salts or compounds containing Ru(II) will dissolve in water in such a ... |
I want a certain Ion in my solution. How do I choose which chemical to buy? |
Let us assume we deal with ideal systems without interactions.
The gel phase and the supernatant solution phase are in thermodynamic equilibrium. The supernatant solution shall consist of different ion species $i$.
The gel is in free swelling equilibrium and the total chemical potential of each ion species $i$ is ... |
Post-script: After recently encountering a related post I re-read my answer here and realized I could have provided a much clearer and more useful definition of equilibrium (rather than my somewhat philosophical earlier answer) that encompasses the different cases you present: in thermodynamics, a system is in an equil... |
$E°_{cell}$ is the EMF of the cell for a reaction with respect to standard hydrogen electrode(SHE). So why don't we represent $E°_{cell}$ or $E_{cell}$ by $\Delta$ symbol, in the same manner in which we represent $∆H°,∆G°,∆S°, etc$ with respect to initial absolute zero temperature? |
Is there any molecular vibrational mode (or activity) that is neither Raman nor IR active?
In other words. Is there any activity in the molecules that can't be captured by either Raman spectrometer (all wavelenght) or IR absorption spectrometer (all wavelenght)? What are those?
|
Boiling point elevation of water by adding salt can be predicted with the formula:
$$\Delta T_b= K_b\, b_{solute} \, i$$
We look for $\Delta T_b=4$, using water $K_b=0.512$, and $i=2$ for salt $\ce{NaCl}$
$b$ is the molality, and an estimate $b=\pu{4 mol/kg}$ as the number $\ce{NaCl}$ moles per kilogram of so... |
Can anyone tell me whether or not air dissolves easily in the R-113? If yes, what is the solubility? From [this link][1] one can only find its solubility in water. It will be better if you could provide a link. Thank you in advance!
[1]: https://en.wikipedia.org/wiki/1,1,2-Trichloro-1,2,2-trifluoroethane |
Does air dissolve in the R-113 (i.e. Freon 113)? |
I have studied that the Grignard Reagent RMgX reacts with CO2 to form RCOOH after acid hydrolysis. But does the same apply for Sulphur Dioxide?
Grignard Reagents are good bases and also good nucleophiles.
So the alkyl anion will attack the electron deficient carbon atom in CO2.
But in the case of SO2 the follow... |
If an individual expelled their intestinal gas in an enclosed space, that smell would seemingly fade away. Why is this so? I would think of 3 possible explanations:
1. The gases dilute in the air. If that space were tightly enclosed and sufficiently small, that smell would persist.
2. The odorous gases decompose ... |
What makes the odor of flatulence fade away? |
Yes it is possible. While no normal modes can be both IR and Raman active in molecules with a centre of symmetry, as mentioned in a comment molecules with silent modes exist.
The easiest example is probably the HCH out-of-plane twisting of ethylene
( can't upload the rough sketch that I have prepared here .????)
D... |
For my thesis research, I dissolved PLA and PCL in chloroform: methanol (3:1), PMMA (350.000 MW, 13 wt%) in acetone, and collagen in acetate acid--and then, I mixed them together. The problem is when I tried to electrospinning with this solution, the needle clogging happened every time. It causes uncontinuous fiber syn... |
How to get rid needle clogging on electrospinning of PLA/PCL/PMMA/Collagen? |
After doing some research and reading I found some problems which I will to state as clearly as possible.
The definition of Gibbs Free Energy says "*the greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing its total volume ... |
What is the true meaning of Gibbs energy and chemical potential? |
After doing some research and reading I found some problems which I will try to state as clearly as possible.
The definition of Gibbs Free Energy says "*the greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing its total vol... |
I have read hat there is two types of electric fields exist in galvanic cell.I understand E because of charges accumulated on electrodes but what about other E -field? What does cause this field and what is the direction? Detailed answer with explanation in terms of ions and charge will be helpful. |
So my book says that the batteries we have considered so far( Daniell cells) are low life span, because they reach equilibrium too fast. In the next paragraph, it says they are also made by irreversible reactions and we call them primary battery. I know that the reactants and products of Daniell cell reach equilibrium ... |
I have studied that the Grignard reagent $\ce{RMgX}$ reacts with $\ce{CO2}$ to form $\ce{RCOOH}$ after acid hydrolysis. But does the same apply for sulfur dioxide?
Grignard reagents are good bases and also good nucleophiles.
So the alkyl anion will attack the electron deficient carbon atom in $\ce{CO2}.$
But in... |
what was the justification for the use the cathode and anode terminology in IEF?
There is no redox taking place in IEF, just proteins interacting with an electric field
[1]: https://en.wikipedia.org/wiki/Isoelectric_focusing
[2]: https://en.wikipedia.org/wiki/Galvanic_cell |
I just add a good mnemonic tool how to remember the naming convention :
**Anode** = **anabasis** ( from Greek ana = "upward", bainein = "to step or march") , electrons would be going upwards from the electrode to the wire = **oxidation**.
> Xenophon, [Anabasis][1], "The March Up Country"
**Cathode** = **cathabasis**... |
I am using charcoal toothpaste for an actor to spit bile on stage during a show. The paste is not the correct state for our needs.
I know that you can freeze toothpaste and it becomes "more" solid and stable at room temperature but still not stable enough.
What organic edible compound(s) could I add to the toothpast... |
I want to cast a cube out of super-absorbent powder (Fake Snow) for an art piece, and make it become shapeless by gradually exposing it to water over 7 days. I have 2 questions:
- What is the best type of glue that I can use to stick it together while keeping it exposable to water + keeping them together after expan... |
In ochem students are taught that shorter bonds (like alkynes) have more energy than longer bonds such as alkanes. However in biochem we are taught that thioesters are very energetic bonds and release alot of energy upon breaking.
Is there a specific mechanism that explains the relationships between bond energy and... |
What is the relationship between bond length and bond energy? Esters vs Thioesters |
I have read hat there is two types of electric fields exist in galvanic cell.I understand E because of charges accumulated on electrodes but what about other E -field? What does cause this field and what is the direction? Detailed answer with explanation in terms of ions and charge will be helpful.
Full thought and... |
Can anyone tell me whether or not air or N$_2$ dissolves easily in the R-113 (liquid solvent) under the saturation pressure of R-113? If yes, what is the solubility roughly? From [this link][1] one can only find its solubility in water.
It will be better if you could provide a link. Thank you in advance!
PS: In Ta... |
The following question was asked on myPAT website:
> [![enter image description here][1]][1]
> [![enter image description here][2]][2]
<hr />
I started with the solution by counting the __Hyper-conjugative__ structures available to each alkene. Based on this concept _only_, order is:
I > II = III > IV
T... |
The following question was asked on myPAT website:
> [![enter image description here][1]][1]
> [![enter image description here][2]][2]
<hr />
I started with the solution by counting the __hyper-conjugative__ structures available to each alkene. Based on this concept _only_, order is:
I > II = III > IV
T... |
I have read hat there is two types of electric fields exist in galvanic cell.I understand E because of charges accumulated on electrodes but what about other E -field? What does cause this field and what is the direction? Detailed answer with explanation in terms of ions and charge will be helpful.
Full thought and... |
For molecular complexes with a moderate amount of symmetry there are usually vibrational modes that are neither infrared nor Raman active. Sometimes these modes transform as some cubic polynomial in x,y,z. For example the $B_{1u}$ irrep in the $D_{4h}$ group which transforms as $xyz$.
My question is: it possible to ... |
Any way to see "cubic-active" vibrational modes in molecules? |
Sulphuric acid can attack benzene and other hydrocarbons (when mixed with hydrogen peroxide), Also Chlorine gas and bromine can replace hydrogen(s) in hydrocarbons like methane,ethane,propane,butane etc. in presence of sunlight and/or mild heating. Can Dil. or Conc. H2SO4 be used to attack Hydrocarbons and produce Sulp... |
Can Sulphuric acid attack a hydrocarbon/Paraffin ? under what conditions? |
Sulfuric acid can attack benzene and other hydrocarbons (when mixed with hydrogen peroxide). Also, chlorine gas and bromine can replace hydrogen(s) in hydrocarbons like methane, ethane, propane,butane etc. in a presence of sunlight and/or mild heating.
Can dil. or conc. $\ce{H2SO4}$ be used to attack hydrocarbons an... |
Can sulfuric acid attack a hydrocarbon/paraffin? Under what conditions? |
For molecular complexes with a moderate amount of symmetry there are usually vibrational modes that are neither infrared nor Raman active. Sometimes these modes transform as some cubic polynomial in x,y,z. For example the $B_{1u}$ irrep in the $D_{4h}$ group which transforms as $xyz$.
My question is: it possible to ... |
> Aqueous copper sulfate solution (blue) gives a green precipitation with aqueous potassium fluoride. Explain these experimental results.
I've read answers like, $\ce{H2O}$ is a weak ligand and fluorine can replace it, but isn't $\ce{H2O}$ a stronger ligand than fluorine according to the spectrochemical series? |
At low concentration, conductivity is proportional to concentration (a linear relationship).
Each ion will have its own unique mobility, as discovered by Kohlrausch. $\ce{H+}$ has the highest mobility. As you can see in your graph the acids have higher conductivities than the salts. $\ce{OH-}$ is also highly mobile.... |
> Arrange in their increasing order of equilibrium constants for hydration:
> [![enter image description here][1]][1]
> (**a**) A < B < C < D < E
> (**b**) A < C < B < E < D
> (**c**) A < C < E < B < D
> (**d**) C < A < B < E < D
How to compare figures E and D? Formaldehyde (figure D) doesn't have ste... |
After doing some research and reading I found some problems which I will try to state as clearly as possible.
The definition of Gibbs Free Energy says "*the greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing its total vol... |
After doing some research and reading I found some problems which I will try to state as clearly as possible.
The definition of Gibbs Free Energy says "*the greatest amount of mechanical work which can be obtained from a given quantity of a certain substance in a given initial state, without increasing its total v... |
In this question,
https://chemistry.stackexchange.com/questions/9743/is-there-an-energy-cost-associated-with-flipping-the-spin-of-an-electron?rq=1, it is shown that it is very unlikely for two hydrogen atoms to bond if their electrons have the same spin, the reason being the very low rate at which such a system would... |
How long would it take for a tank of same-spin hydrogen atoms to become a tank of $H_2$? |
In the question
[Is there an energy cost associated with flipping the spin of an electron?](https://chemistry.stackexchange.com/q/9743/), it is shown that it is very unlikely for two hydrogen atoms to bond if their electrons have the same spin. The reason is the very low rate at which such a system would be able to em... |
How long would it take for a tank of same-spin hydrogen atoms to become a tank of H₂? |
In the question
[Is there an energy cost associated with flipping the spin of an electron?](https://chemistry.stackexchange.com/q/9743/), it is shown that it is very unlikely for two hydrogen atoms to bond if their electrons have the same spin. The reason is the very low rate at which such a system would be able to em... |
qualitatively: Why are thioesters more reactive than regular esters? |
While studying about the entropy change of surroundings in irreversible adiabatic process, I cam across a sentence
> for infinite reservoir, all processes are considered reversible. ..
And suddenly it resumes with the equation:
q/T = dS (surrounding)
Can anyone explain the line and how the conclusion was drawn?
|
While studying about the entropy change of surroundings in irreversible adiabatic process, I came across a sentence.
> For infinite reservoir, all processes are considered reversible
And suddenly it resumes with the equation:
q/T = dS (surrounding)
Can anyone explain the line and how the conclusion was drawn?
|
This question has been asked before, but the answers are not clear and satisfactory.
If the pressure and the temperature are constant then G would be always zero. How would then G have a value other than 0? |
Why Gibbs energy change of a process can be negative at constant temperature and pressure? |
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