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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:
$$\ce{-NR3+} > \ce{-NH3+} \qquad \ce{-OR} > \ce{-OH}$$
I don't understand why it should be that way, as an alkyl group... |
[![Acetamidine and 2-Imidazoline][1]][1]
My approach:
1. Conjugate acids of both molecules have the same number of stable resonance structures. So no conclusion from here.
2. Conjugate acid of 2-Imidazoline will have negative inductive on the lone pair donating nitrogen by the other nitrogen atom. Since this e... |
>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:
>$−NR_3^+>−NH_3^+$<br><br>
>$−OR>−OH$
About comparing $−NR_3^+$ and $−NH_3^+$, at first, the electron-donating indu... |
My speculation, on what is occurring, is that the Iron pipe in your shower is displacing some dissolved copper (possibly as bicarbonate). The likely acidic rainwater may also contain chloride or nitrate salts, which may further complex with the fresh active copper precipitate. Here is a related illustrative source, per... |
>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:
>$−NR_3^+>−NH_3^+$<br><br>
>$−OR>−OH$
About comparing $−NR_3^+$ and $−NH_3^+$, at first, the electron-donating indu... |
My speculation, on what is occurring, is that the Iron pipe in your shower is displacing (upon standing over time) some dissolved copper (possibly as bicarbonate). The likely acidic rainwater may also contain chloride or nitrate salts, which may further complex with the fresh active copper precipitate. Here is a relate... |
My speculation, on what is occurring, is that the Iron pipe in your shower is displacing (upon standing over time) some dissolved copper (possibly as bicarbonate). The likely acidic rainwater may also contain chloride or nitrate salts, which may further complex with the fresh active copper precipitate. Here is a relate... |
First, thanks for reporting some obvious unexpected chemistry occurring. Others in your community may also have similar metal leaching issues, which especially for children, may be a health concern (see, for example, [this article](https://www.ewg.org/childrenshealth/22713/nitrates-tap-water-what-parents-need-know)).
... |
As far I know ethanol is soluble in water in all proportion, and since water is polar it would imply that ethanol is also polar and only possible polar group in ethanol is the -OH group.
Since oxygen is much more electronegative than hydrogen, so oxygen have to attract the electron pair towards itself forming a pola... |
Why ethanol don't conduct electricity? |
I read that Mg^2+ and cl^-1 come together because of electrostatic force or coulomb force and form an ionic bond. Then why is the formula MgCl2.why does 1 mg^2+ attract 2 clorides only if coulomb's law is at work and form an ionic bond with 2 clorides only? Because when the ions come close and form a bond ,they dont d... |
Why is it MgCl2 and not MgxCly? |
For temperature dependence of Gibbs energy, Why we Gibbs-Helmholtz equation rather than finding directly in the same way as Gibbs energy dependence of Pressure? |
I read that Mg^2+ and cl^-1 come together because of electrostatic force or coulomb force and form an ionic bond. Then why is the formula MgCl2.why does 1 mg^2+ attract 2 clorides only if coulomb's law is at work and form an ionic bond with 2 clorides only? When the ions come close and form a bond ,they dont distribut... |
Does the toxicity of an element depend on the state of matter (liquid, solid, gas)?
Could there be an element, which is totally non-toxic when it is solid, but toxic when it is liquid. Which elements would fall in that category? |
Does toxicity depend on state of matter? |
For temperature dependence of Gibbs energy, Why we Gibbs-Helmholtz equation rather than finding directly in the same way as Gibbs energy dependence on pressure?
$$dG/dP = V => dG = VdP \tag{for Solids and liquids}$$
By pressure I mean external pressure applied. Like for gases $dG = nRT \ln(p_f/p_i)$. Why we use... |
I read that e.g. $\ce{Mg^{2+}}$ and $\ce{Cl-}$ come together because of electrostatic force or coulomb force and form an ionic bond. Then why is the formula $\ce{MgCl2}$? Why does one $\ce{Mg^{2+}}$ attract only two chlorides (if Coulomb's law is at work) and form an ionic bond with two chlorides only? When the ions co... |
Why do ionic compounds form in the exact ratios that they do instead of more variable ratios? |
How many deuterium atoms (symbol D for deuterium) are present in $\pu {3.00 x 10^{-6} g}$ of water?
**Answer:**
$$\pu{3.00 x 10^{-6} g} \;\ \ce{H2O} \times \frac{\pu{1 mol} \;\ce{H2O}}{\pu{18.015 g} \;\ce{H2O}}\times \frac{\pu{2 mol} \;\text{H}}{\pu{1 mol} \;\ce{H2O}}\times 0.000156 \times \frac{N_\mathrm A \;\te... |
For temperature dependence of Gibbs energy, Why we Gibbs-Helmholtz equation rather than finding directly in the same way as Gibbs energy dependence on pressure?
$$\frac{\mathrm dG}{\mathrm dp} = V \Rightarrow \mathrm dG = V\,\mathrm dp \quad\text{for solids and liquids}$$
By pressure I mean external pressure ap... |
[![Acetamidine and 2-imidazoline][1]][1]
My approach:
1. Conjugate acids of both molecules have the same number of stable resonance structures. So no conclusion from here.
2. Conjugate acid of 2-imidazoline will have negative inductive on the lone pair donating nitrogen by the other nitrogen atom. Since this e... |
Is there any single element (e.g. possibly carbon) that can be eaten, which has a nutritional value such that it provides calories?
I found on Wikipedia ([dietary element][1]) that there are certain elements that our bodies require. I suppose oxygen could count as such a nutritional element, although we breathe it ... |
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 the result of my limited chemistry understanding. Something with ar... |
I would like to get the molecular structure as SMILES from Gaussian output files. OpenBabel seems to be the tool made for such tasks.
However, the structure is not always correct.
One example:
[![enter image description here][1]][1]
OpenBabel conversion Gaussian09 to SMILES (left):
N1(c2ccccc2)[C]2C=CC... |
Is there a way to convert Gaussian input files (`.gjf`) to SMILES-codes (`.smi`)?
I'm aware of `Open Babel` (http://openbabel.org/docs/2.3.0/FileFormats/Overview.html), but this lists `.gjf` as a "write-only" format. Is there, nevertheless, a way (which ideally can be integrated into a Python application) to convert... |
Is there free software that can calculate the fluorescence emission spectra of organic molecules?
Let's say, for example, rubrene
There is a bunch of quantum free quantum chemistry software:
https://en.wikipedia.org/wiki/List_of_quantum_chemistry_and_solid-state_physics_software
However, which one would be the m... |
Sorry for a layman question. I'm having difficulties understanding some basic math apparently.
According to a [paper][1], for a coronavirus, the UVGI dose for 90% inactivation is 339–423 μW sec/cm2.
I have a UV lamp with the following specifications:
- it's 15 watts
- it takes _1h30_ min to 90% inactivate cor... |
As far I know ethanol is soluble in water in all proportions, and since water is polar it would imply that ethanol is also polar and the only possible polar group in ethanol is the -OH group.
Oxygen is much more electronegative than hydrogen, so oxygen has to attract the electron pair towards itself forming a polar ... |
Why doesn't ethanol conduct electricity? |
I read that e.g. $\ce{Mg^{2+}}$ and $\ce{Cl-}$ come together because of electrostatic force or coulomb force and form an ionic bond. Then why is the formula $\ce{MgCl2}$? Why does one $\ce{Mg^{2+}}$ attract only two chlorides (if Coulomb's law is at work) and form an ionic bond with two chlorides only? When the ions co... |
As far I know ethanol is soluble in water in all proportions, and since water is polar it would imply that ethanol is also polar and the only possible polar group in ethanol is the -OH group.
Oxygen is much more electronegative than hydrogen, so oxygen has to attract the electron pair towards itself forming a polar ... |
>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^+$<br><br>
>$−OR>−OH$
About comparing $−NR_3^+$ and $−NH_3^+$, at first, the electron-donating indu... |
Why should pure water and pure ethanol dissociate ? Substances get dissociated into ions if they win some stability in this process. NaCl is more stable in the dissociated state than in the covalent. In ionic NaCl, all atoms look like rare gases, and respect the octet rule. In a theoretically covalent structure, Na doe... |
I see a lot of questions on electron configurations from students at various levels here. Students mechanically remember how to fill orbitals and sorry to say many teachers do the same. Not a single general chemistry or even undergraduate physical chemistry book discusses the "why" part of orbital filling and what is t... |
For longitudinal relaxation, one would think that the magnetic moment obeys this simple relationship
$$M_z = M_0\left[1 - 2\exp\left(\frac{t}{T_1}\right)\right].$$
However there is always a point of inflection when magnetisation is zero. Does anyone knows why?
edit: I deleted the image and added some from my ... |
[![Structures of acetamidine and imidazoline][1]][1]
My approach:
1. Conjugate acids of both molecules have the same number of stable resonance structures. So no conclusion from here.
2. Conjugate acid of 2-imidazoline will have negative inductive on the lone pair donating nitrogen by the other nitrogen atom. ... |
For longitudinal relaxation, one would think that the magnetic moment obeys this simple relationship
$$M_z = 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?
edit: I deleted the image and added some from my... |
> Why we use this equation [and ...] not this equation?
It depends what problem you want to solve.
$\frac{dG}{dT}$ is of interest, for example, if you want to know the maximum work available from a process at different temperatures.
$\frac{d(G/T)}{dT}$ is of interest, for example, if you want to know how the e... |
[![enter image description here][1]][1]
I guess my main question is looking only at the newman projection how does one determine the stereochemistry?
In the molecule to the right, I get for the first carbon, (et, H, Me,) R ( I flipped it after moving the H back) and for C2 (Et, Br, Me) I get S.
[![enter ima... |
How to figure out the most stable conformation of the diastereomer? |
It is observed that the order of second ionisation energy of these three elements is $\ce{Zn > Cd < Hg}$.
Why is there an anomaly in the observation? |
Today I was introduced to the Orbital Wave Function for electrons.
Ψ is a mathematical function for coordinate of electrons and has no physical meaning.
But ψ^2 gives probability of an electron.
How does a function for coordinate give probability distribution when squared ? How is the ψ working ?
Please explain ... |
Why does ψ^2 ( square of orbital wave function ψ) give the probability of an electron in a given region? |
Today I was introduced to the Orbital Wave Function for electrons.
$\Psi$ is a mathematical function for coordinate of electrons and has no physical meaning.
But $\Psi^2$ gives probability of an electron.
How does a function for coordinate give probability distribution when squared ? How is the $\Psi$ working ?
... |
Like any other linear polymer sucu as proteins and DNAs, RNA structure has two ends. Like carboxylic acid end and amine end notation given for proteins, two ends of a RNA (and DNA) call 3'-end and 5'-end (see the diagram below):
[![RNA Structure][1]][1]
Note that these notations are derived from the numbering of... |
Like any other linear polymer sucu as proteins and DNAs, RNA structure has two ends. Like carboxylic acid end and amine end notation given for proteins, two ends of a RNA (and DNA) call 3'-end and 5'-end (see the diagram below):
[![RNA Structure][1]][1]
Note that these notations are derived from the numbering of... |
The reaction:
$$\ C\ (s)+O_2\ (g) \to CO_2\ (g)$$
Is exothermic and entropically favorable. My question is: why is this reaction entropically favorable?
Clearly there are more ways to arrange $C\ (s)$ and $O_2$ in a container than $CO_2$.
Sure, the $CO_2$ has degrees of freedom in it's vibrations, but thes... |
Why does the combustion of graphite have a positive $\Delta$S? |
>The following reaction is exothermic and entropically favorable:
>$$\ce{C (s) + O2 (g) \to-> CO2 (g)}$$
>My question: Why is this reaction entropically favorable?
Clearly there are more ways to arrange $\ce{C (s)}$ and $\ce{O2 (g)}$ in a container than $\ce{CO2}$.
Sure, the $\ce{CO2}$ has degrees of freed... |
>The following reaction is exothermic and entropically favorable:
>$$\ce{C (s) + O2 (g) -> CO2 (g)}$$
>My question: Why is this reaction entropically favorable?
Clearly there are more ways to arrange $\ce{C (s)}$ and $\ce{O2 (g)}$ in a container than $\ce{CO2}$.
Sure, the $\ce{CO2}$ has degrees of freedom ... |
Why does the combustion of graphite have a positive Delta S? |
Do molecules with bridges through rings (like this one) exist?
[![example diagram][1]][1]
I sometimes get results like this when doing Energy Minimization on molview.org. For example: [![molview.org Jmol result][2]][2]
Is this actually a thing?
[1]: https://i.stack.imgur.com/86Cq3.png
[2]: https://i.... |
Do molecules with bridges through rings exist? |
The following articles suggest that the data reported from Solomons, Fryhle and Snyder Organic Chemistry is likely **incorrect.**
- Maya Paabo, Roger G. Bates and R. A. Robinson ("[Dissociation of Acetic Acid-d3 in Aqueous Solution and Related Isotope Effects from 0 to 50°](https://doi.org/10.1021/j100874a037)", J.... |
Do molecules with bridges through rings (like this one) exist?
[![example diagram][1]][1]
I sometimes get results like this when doing Energy Minimization on molview.org. For example: [![molview.org Jmol result][2]][2]
Is this actually a thing?
EDIT: As a more realistic example, consider this: [![slightly l... |
I'm interested in trying a new gel electrophoresis buffer using lithium acetate. Before making a financial commitment, someone was able to provide me with enough lithium acetate from a different lab to try the buffer first. Lithium acetate is produced in both anhydrate and dihydrate form. The problem is that this batch... |
Suppose I release 1 mole of pure argon into the atmosphere. What is the entropy of mixing? The equations I have found seem to only apply to the case of a fixed volume. Should I use an estimate of the volume of the whole atmosphere? Some sort of infinite approximation? |
What is the entropy of mixing a gas into the whole atmosphere? |
Okay so no one answered OP properly. Molality(m) is independent of the temperature as long as the temperature change does not actually change the amount of solute. I understand that most resources would not mention this simple fact and expect you to understand it presumptuously. Again, molality(m) is independent of tem... |
I was given this problem recently to compute the number of ions in a unit cell of Ferrous oxide $\ce{FeO}$. The data given was:
> Side length $a = \pu{5 Å}$
> Density $d = \pu{4 g/cc}$
Using the formula $d = \frac {ZM}{N_0 a^3}$, I obtained $Z = 4.18$. However, the answer had rounded Z off to 4.
**Could a uni... |
Does a unit cell have to contain a whole number of atoms? |
My textbook says
> Molarity is dependent on temperature, whereas molality is not.
I'm aware of the definitions of both molarity and molality, but consider this scenario:
A solution of $\ce{NaCl}$ in $\ce{H2O}$ is heated. Eventually, all the water will escape and I will be left with only $\ce{NaCl}$ crystals. A... |
Can anyone inform me what the term **stoichiometric amounts** means? I know what stoichiometry means. It is the:
> The relationship between the relative quantities of substance taking part in a reaction or forming a compound.
But what is "stoichiometric amount" supposed to be? |
What does "stoichiometric amounts" mean? |
Great question!
When I was teaching, Anslyn and Dougherty was a decent text for this. Here are some general comments:
1. First, please note that you _cannot_ be sure about a mechanism. That's the real killer. You can devise experiments that are consistent with the mechanism but because you cannot devise and run a... |
I want to make a very shiny surface, like a mirror. I tried to use chrome paint but it's barely shiny. It's more like gray even though I bought one of the most expensive chrome looking paint.
I know mirrors can be produced using Tollen's reagent on glass (seen some demonstrations on YouTube).
But glass is quite ... |
I found a video on YouTube making a [mirror on PET bottles][1].
Just that it consumes quite a lot of substance, and is not using Tollens reagent. My question is specifically about Tollens reagent.
What she uses is some "secret mixture" called RA-205.
It just proves that Ag can precipitate on PET bottles, whi... |
Would a [2]catenate whose each ring consist of a different number of methylene groups only, be optically active if one hydrogen atom of a random methylene group is replaced with e.g. chlorine? I think yes, but I need a second opinion.
The compounds attached seem to be enantiomers. I don't see how, by rotation, they ... |
It depends on what you mean by ceiling. Are we talking about a practical or theoretical limit?
At a high enough energy, the stress-energy tensor will be large enough that you're going to make a black hole. I'm not sure we understand the astrophysics well enough to know what this will look like in the limits you refe... |
There are a number of possible explanations for the entropy difference, which can be computed based on [standard free energies][1] and [enthalpies][2] of formation as $\pu{3.0 J/molK}$. First, it could be that the entropy change is so small ($TΔS^∘<\pu{1 kJ}$, compare this to $ΔH^∘=\pu{−393.5kJ/mol}$) and measurement t... |
Which change occurs in all exothermic reactions? |
> Which change occurs in all exothermic reactions?
> **A**) Bubbles of gas are released from the mixture.
> **B**) Light energy is produced.
> **C**) The temperature of the mixture decreases.
> **D**) The temperature of the mixture increases.
I'm stuck with choosing between **A**, **B** and **C**, but I ... |
Despite wide variety of existing experimental methods producing electron/charge density maps, I failed to find a good dataset of experimental data for small (1-3 atoms) molecules.
There are datasets for integral properties such as https://cccbdb.nist.gov/ . It is fairly trivial to find atomic spectra data on NIST s... |
Is there any collection of charge density maps for small molecules? Any good data at all? |
I have fond that similar question has been asked already (https://chemistry.stackexchange.com/questions/78767/why-dont-carbons-use-sp3-instead-of-sp2-orbitals-to-make-double-bonds), but I don't think it was formulated in a manner that was touching the concept I am interested in.
I would like to know is it reasonable... |
Multiple bonds solely with sp3 hybridised orbitals? |
Why are some elements like Ge and Si have liquids denser than their solids? In water it is explainable by H bonding, but no H bonds or such are there in Ge and Si. |
Why is liquid germanium denser than solid germanium? |
Why are some elements like Ge and Si have liquids denser than their solids? In water it is explainable by H bonding, but no H bonds or such are there in Ge and Si.
Well, I want an explanation about the structure formed by Ge and Si in their solid state which makes them less dense than their liquids, and also the bonds... |
Some years ago, due to a translation error that I only discovered later, I made cyanotypes using a mixture of ammonium ferric citrate and potassium ferr**o**cyanide instead of ferr**i**cyanide. This worked, although they seemed to be less sensitive (reacted slower to sunlight) than the guide I was trying to follow, but... |
We performed an experiment in class where we placed a piece of Copper wire in a solution of Silver Nitrate, we were tasked with predicted the mass of Copper that should react and the mass of Silver that should be formed. My question is this, **what are indicators of Cu(I) and Cu(II) ions?**
2AgNO<sub>3(aq)</sub> + C... |
I recently broke a Quickfit distillation thermometer and the bulb had liquid metal in it. I assumed it's mercury and acted accordingly. However, the column looks like spirit filled (blue liquid). Has anyone seen those, and if so, do you know if the metal is indeed mercury or something else? The model is Quickfit MF 31/... |
Mercury bulb on spirit thermometer? |
I recently broke a Quickfit distillation thermometer and the bulb had liquid metal in it. I assumed it's mercury and acted accordingly. However, the column looks like spirit filled (blue liquid). Has anyone seen those, and if so, do you know if the metal is indeed mercury or something else? The model is Quickfit MF 31/... |
> In the reaction in equilibrium
>
> $$\ce{2HI <=> H2 + I2}$$
>
> The value $K_c$ is $0.0198$ at $\pu{721 K}$. Calculate $\ce{[HI]}$ at $\pu{721 K}$ if $\ce{[H2]} = \pu{0.0120 M}$ and $\ce{[I2]} = \pu{0.0150 M}$.
We use an ICE box. Since $K < 1$, the equilibrium is to the left. We are spending products to crea... |
My background is macromolecular crystallography; while experimental data was kept locked in the research laboratories in the 1980s, they are now widely available through the international protein database. For example, you can view the electron density of crambin at http://www.rcsb.org/3d-view/1EJG.
The database for... |
Pursuing a question raised in [these comments](https://chemistry.stackexchange.com/a/6379/5354):
**Are there any known pharmaceuticals that increase in potency or toxicity during storage, or over periods of months to years?**
If not, what if we broaden the question to include any bioactive chemical?
My hypothe... |
Do any pharmaceuticals increase in potency or toxicity over time? |
Pursuing a question raised in [these comments](https://chemistry.stackexchange.com/a/6379/5354):
**Are there any known pharmaceuticals that increase in potency or toxicity during storage, or over periods of months to years?**
If not, what if we broaden the question to include any bioactive chemical?
My hypothe... |
Pursuing a question raised in [these comments](https://chemistry.stackexchange.com/a/6379/5354):
**Are there any known pharmaceuticals that increase in potency or toxicity during storage, or over periods of months to years?**
If not, what if we broaden the question to include any bioactive chemical?
My hypothe... |
I have a few questions regarding rate and rate constant. I am wondering what effect certain concentrations, temperature, etc., has on rate and rate constant. Would be of great help if you can clarify this for me!
If a concentration was halved (and all other factors remained the same), does that mean rate would decre... |
What effect is on the rate and rate constant when concentration or temperature increases/decreases? |
I would like to solder a drain fitting onto my ultrasonic cleaner's tank. The fitting and the tank are both stainless steel. During its operation, the tank is filled with a cleaning solution and heat is applied to accelerate the process.
I'm concerned the silver solder joint and or the tank itself may become comprom... |
Should I be concerned about a galvanic reaction between silver solder and stainless steel? |
I was given this problem recently to compute the number of ions in a unit cell of ferrous oxide $\ce{FeO}$. The data given was:
> Side length $a = \pu{5 Å}$
> Density $d = \pu{4 g/cc}$
Using the formula $\displaystyle d = \frac {ZM}{N_0 a^3}$, I obtained $Z = 4.18$. However, the answer had rounded $Z$ off to $... |
For my Chemistry investigation, I used stamm's potassium permamganate method to investagte tea tannins with potassium permanganate to find the tannin content of teas. The method assumes complete oxidation of tea polyphenols to carbon dioxide. Assuming that the tea polyphenols consist of only theaflavins, C29H24O12, and... |
Redox: Could someone give me the equation for the reaction of oxidation of tea teaflavins and EGCG with potassium permanganate? |
For my chemistry investigation, I used Stamm's potassium permamganate method to investagte tea tannins with potassium permanganate to find the tannin content of teas. The method assumes complete oxidation of tea polyphenols to carbon dioxide.
Assuming that the tea polyphenols consist of only theaflavins, $\ce{C29H2... |
We performed an experiment in class where we placed a piece of copper wire in a solution of silver nitrate, we were tasked with predicted the mass of copper that should react and the mass of silver that should be formed. My question is, **what are indicators of Cu(I) and Cu(II) ions?**
$$\ce{2 AgNO3(aq) + Cu(s) -> C... |
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