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I'm working on a chemical design project where zeolite crystals containing Na+ cations is ion-exchanged via an aqueous solution of AgNO3, Cu(NO3)2, and Zn(NO3)2, also containing HNO3. The solid product now containing Ag+, Cu2+, and Zn2+ cations is removed from the solution and dried. I expect the remaining Ag+, Cu2+, Z... |
What happens to dissolved ions when an aqueous solution evaporates? |
I'm working on a chemical design project where zeolite crystals containing Na+ cations is ion-exchanged via an aqueous solution of $\ce{AgNO3}$, $\ce{Cu(NO3)2}$, and $\ce{Zn(NO3)2}$, also containing $\ce{HNO3}$. The solid product now containing $\ce{Ag+}$, $\ce{Cu^2+}$, and $\ce{Zn^2+}$ cations is removed from the solu... |
My preconception is that when you fill an empty orbital by exciting an electron (with a photon), the empty orbital should be filled by an electron with the same spin. However, I've seen examples of that happening and not happening. For example, on [this University of Calgary
web page](http://www.chem.ucalgary.ca/cour... |
Does an electron's spin change when being excited? |
I am confused with my teacher's explanation for the nomenclature of this organic compound.
[![enter image description here][1]][1]
He said that we should start numbering from the sulphonic acid at the bottom of the structure. But one of the students asked if we should start numbering from the other sulphonic acid... |
When you carry out iodometric titration for determining the Peroxide value of a phospholipid mixture, the end point is the solution turning colourless. But, after some time the colour reappears. Do you stop at the first discoloration or continue titrating with sodium thiosulphate? |
The [Committee on Data of the International Science Council (CODATA)](https://en.wikipedia.org/wiki/Committee_on_Data_for_Science_and_Technology) was established as ICSU Committee on Data for Science and Technology in 1966.
Avogadro constant, [CODATA recommended values](https://physics.nist.gov/cuu/Constants/index.... |
The [Committee on Data of the International Science Council (CODATA)](https://en.wikipedia.org/wiki/Committee_on_Data_for_Science_and_Technology) was established as ICSU Committee on Data for Science and Technology in 1966.
Avogadro constant, [CODATA recommended values](https://physics.nist.gov/cuu/Constants/index.... |
I read some information about phenolphthalein indicator, some websites suggested phenolphthalein indicator of 1%, others mentioned phenolphthalein indicator of 0.1%. What is the difference of both of these concentrations when we use them in titrations?
I assume that 1-2 drops of phenolphthalein indicator of 1% can b... |
What concentration is phenolphthalein indicator ? 1% or 0.1% |
My preconception is that when you fill an empty orbital by exciting an electron (with a photon), the empty orbital should be filled by an electron with the same spin. However, I've seen examples of that happening and not happening. For example, on [this University of Calgary
web page](http://www.chem.ucalgary.ca/cour... |
I've been told how to apply the ECR to GaAs{001}(2×4) in my lectures but it makes no sense to me and I don't seem to be able to find any other sources that explain this. (This is a further question on another one posted [here](https://physics.stackexchange.com/questions/605758/which-is-the-correct-gaas0012%c3%974-struc... |
How is ECR (Electron Counting Rule) done in a structure? |
Porous materials: Is the expression of a mean free path $\overline{\ell}$ of the gas molecule valid for a binary mixtures? |
As I understand it Lipoic acid is [synthesized from octanoic acid][1]:
> Lipoic acid is synthesized de novo in mitochondria from octanoic acid, an 8-carbon fatty acid (C8:0), bound to the acyl-carrier protein (ACP; see article on Pantothenic Acid) during the process of fatty acid synthesis (Figure 2).
However, I... |
How much lipoic acid is contained within octanoic acid? |
I have a question concerning acid/base reactions. Is it true that an alcohol is a better base than water?
My Professor listed the basicity (because we talked about E1/E2 and Sn1/Sn2 reactions) of the following compounds the following way: RO- > OH- > ROH > H2O (with stronger base being the RO- and the weakest here H2O... |
Base/acid reaction -> alcohol amphoteric? why no pkb value? |
As I understand it, Lipoic acid is [synthesized from octanoic acid][1]:
> Lipoic acid is synthesized de novo in mitochondria from octanoic acid, an 8-carbon fatty acid (C8:0), bound to the acyl-carrier protein (ACP; see article on Pantothenic Acid) during the process of fatty acid synthesis (Figure 2).
However, ... |
Neither the 1.7 electtonegativity difference rule nor the metal-nonmetal rule for ionic bonding us really correct, as Ivan points out in the comments. Following are some well-documented exceptions to both rukes:
* The chart given [here](https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=16329), illustrated below, ... |
Neither the 1.7 electtonegativity difference rule nor the metal-nonmetal rule for ionic bonding is really correct, as Ivan points out in the comments. Following are some well-documented exceptions to both rules:
* The chart given [here](https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=16329), illustrated below, ... |
At the weekend, my son and I tried the volcano experiment. You know the one: vinegar introduced to sodium bicarb (and a little red dye) within a conical "volcano".
[![An erupting papier mache volcano][1]][1]
<sub>*Not actually ours; photo borrowed from [here][2].*</sub>
So, after assiduously funnelling some (s... |
Why did my vinegar not create the traditional volcano? |
AlCl3 is said to be an electron deficient compounds as Al only has 6 electrons in its valence shell. Why doesn’t it just form a dative bond with one of the chlorine’s? I know this gives the more electronegative chlorine a positive formal charge, but then the diner AlCl3 shouldn’t exist either.
How does forming a da... |
Why doesn’t AlCl3 form the dative bond with itself? |
AlCl3 is said to be an electron deficient molecule as Al only has 6 electrons in its valence shell. Why doesn’t it just form a dative bond with one of the chlorine’s? I know this gives the more electronegative chlorine a positive formal charge, but then the diner Al2Cl6 shouldn’t exist either.
How does forming a da... |
Why doesn’t AlCl3 form the dative bond within the same molecule? |
In a [concentration cell][1], one can measure a voltage because in one of the half cells (the one with lower concentration electrolyte), the atoms tend to dissipate more into the electrolyte as ions, leaving more electrons behind (compared to the other half cell), thus creating a current.
I am not sure if I understa... |
Why does lower concentration cause the metal atoms to dissipate more? |
I've come across an interesting protocol for photochemical reduction of benzophenone to benzhydrol (diphenyl methanol) with sodium alcoholate in alcohol, the 2nd protocol in <https://prepchem.com/synthesis-of-diphenylmethanol/>. The reaction proceeds via [ketyl radical](https://en.wikipedia.org/wiki/Ketyl) initially to... |
Photochemical reduction of benzophenone: why inverted flask? |
As I understand it, lipoic acid is [synthesized from octanoic acid][1]:
> Lipoic acid is synthesized de novo in mitochondria from octanoic acid, an 8-carbon fatty acid (C8:0), bound to the acyl-carrier protein (ACP; see article on Pantothenic Acid) during the process of fatty acid synthesis (Figure 2).
However, ... |
Why is H2O a weaker acid than acetylacetone? Shouldn't a hydrogen connected to an oxygen be more acidic than a hydrogen connected to a carbon atom? |
The [Committee on Data of the International Science Council (CODATA)](https://en.wikipedia.org/wiki/Committee_on_Data_for_Science_and_Technology) was established as ICSU Committee on Data for Science and Technology in 1966.
Avogadro constant, [CODATA recommended values](https://physics.nist.gov/cuu/Constants/index.... |
>General Chemistry perspective: Looking at the molecular orbitals of water, we can see that the oxygen is $\mathrm{sp}^3$ hybridized.
No. One could say that, but $\mathrm{sp}^2$ is equally possible. In fact, it may seem more likely, we’ll get to that in a second.
>Group Theory and Quantum Chemistry perspective: W... |
[![enter image description here][1]][1]
In a zinc-copper voltaic cell,
What causes the initial electron movement from the zinc to the copper?
I understand that copper would pull the electrons more strongly than zinc, but only if it is electron deficient. Both half cells of the voltaic cell are electrically... |
What start the reaction in a voltaic cell? |
If I have some solid material like biomass and incinerate it at 1000 Celsius degrees for 15 minutes in an oxidized atmosphere within an incineration oven. As an output it gives me ash. Is the incineration complete or incomplete? Like for example we have incomplete combustion (lack of oxygen) and complete combustion (en... |
Is incineration of a solid fuel complete or incomplete? |
I was doing research on buckwheat sprouts (as to whether I should include them in my diet) and I came across a website that said eating too much can cause fagopyrism, which is caused by compounds called fagopyrins:
[![enter image description here][1]][1]
I was just wondering how they came to the conclusion that i... |
Is there a way to predict whether a compound will be toxic or not? |
How are the toxic components in a mixture identified? |
I'm studying equilibria and thermodynamics and came across these two terms.
My problem is, unlike other thermodynamic properties that I can understand physically like Volume, Pressure, Enthalpy etc. **do these two quantities have physical significance** or, is it just that we define fugacity(without any physical mea... |
Could mechanical blending denature alpha amylase / glucoamylase enzymes? |
I think a really full answer will require delving into the theory of NUS, which (just like the Fourier transform) goes way beyond NMR as a field: the idea of undersampling a signal and then reconstructing it is of great interest in a variety of engineering areas. I can't give that level of detail, but there are a few t... |
I think a really full answer will require delving into the theory of NUS, which (just like the Fourier transform) goes way beyond NMR as a field: the idea of undersampling a signal and then reconstructing it is of great interest in a variety of engineering areas. I can't give that level of detail, so I don't pretend th... |
Could shear force from blending denature alpha amylase / glucoamylase enzymes? |
I'm studying equilibria and thermodynamics and came across these two terms.
My problem is, unlike other thermodynamic properties that I can understand physically like Volume, Pressure, Enthalpy etc. **do these two quantities have physical significance** or, is it just that we define fugacity(without any physical mea... |
The question came to my mind as to whether the effect of a catalyst on a reaction included the modification of the frequency factor (or pre-exponential factor) of a reaction, shown in Arrhenius' Equation below as "$A$":
$$K=Ae^{\frac{-E_a}{RT}}$$
On the one hand, we know that catalysts reduce the activation energ... |
The question came to my mind as to whether the effect of a catalyst on a reaction included the modification of the frequency factor (or pre-exponential factor) of a reaction, shown in Arrhenius' Equation below as "$A$":
$$ k = A\exp{\left(\frac{-E_\mathrm{a}}{RT}\right)}$$
On the one hand, we know that catalysts ... |
I would have said that the answer was no, because lithium is less reactive than potassium is, so you would expect the reaction to go the other way: with potassium and lithium chloride reacting to produce lithium metal and potassium chloride.
However, this Youtube video from Cody's Lab appears to show that the answer... |
Can you get potassium by reducing KCl with lithium? |
I would have said that the answer was no, because lithium is less reactive than potassium is, so you would expect the reaction to go the other way: with potassium and lithium chloride reacting to produce lithium metal and potassium chloride.
However, this Youtube video from Cody's Lab appears to show that the answer... |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
**Please edit the table to include missing data**
Avogadro constant in the "CRC Handbook of Chemistry and Physics"
| Edition | Years(s) | page | value | CODATA? |
|---------|-----------|-------|--------------|-------------------|
| 1 [(Link)](https://books.google.com/books?id=07AHIEp6vYQC&printse... |
The $\ce{[PbCl4]^{2-}}$ complex ion is formed when $\ce{PbCl2}$ is exposed to excess $Cl^-$ ions in solution as explained [here](https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Supplemental_Modules_(Analytical_Chemistry)/Qualitative_Analysis/Characteristic_Reactions_of_Select_Metal_Ions/Characteristic_Reac... |
WHY DOES THE INFRARED SPECTRUM OF HCl ONLY HAVE ONE PEAK? |
It is known that the inhibition of acetylcholinesterase by isomalathion can proceed either with diethyl succinate as the leaving group or thiomethyl, depending on the specific stereoisomer of isomalathion. Does the mechanism of inhibition of AChE by the Parathion isomer O,S-Diethyl O-4-Nitrophenyl thiophosphate (Or its... |
Does the mechanism of AChE inhibition by Isoparathion depend on chirality? |
Neither the 1.7 electtonegativity difference rule nor the metal-nonmetal rule for ionic bonding is really correct, as Ivan points out in the comments. Following are some well-documented exceptions to both rules:
* The chart given [here](https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=16329), illustrated below, ... |
This is regarding a situation where an atom has five electron domains; two domains are lone pairs, and three are bonds to other atoms.
The course materials I am using (focusing on VSEPR theory) suggest that, as a rule of thumb, T-shaped geometry is the configuration the electron domains around an atom will take in ... |
Why is T-shaped geometry preferred to trigonal planar geometry for the bonds around atoms with 3 bonds and 2 lone pairs? |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/lbT0T.jpg
So I understand that if twice as much of the reactants are present, then twice as much energy is released. But isn’t the energy released *per* mole of reactant still the same? You are just scaling up both sides of the equation, I.e. t... |
Why does $/Delta H$ change when the coefficients change in a reaction? |
The answer is simple: By convention, the values given for the changes in thermodynamic state functions $(\Delta G, \Delta H, \Delta S, \Delta A, \Delta U$, etc.) are for the reaction *as written*, and **not** per mole.
The reason for this is that, if it were per mole, then the question would arise: per mole of *w... |
The answer is simple: By convention, the values given for the changes in thermodynamic state functions $(\Delta G, \Delta H, \Delta S, \Delta A, \Delta U$, etc.) are for the reaction *as written*, and **not** per mole.
The reason for this is that, if it were per mole, then the question would arise: per mole of *w... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/lbT0T.jpg
So I understand that if twice as much of the reactants are present, then twice as much energy is released. But isn’t the energy released *per* mole of reactant still the same? You are just scaling up both sides of the equation, I... |
Why does Delta H change when the coefficients change in a reaction? |
How do oxide formations affect volatic cells? |
How do oxide formations affect voltaic cells? |
How would it be found the Gibbs energy at a certain temperature, if they just give you another Gibbs energy at a temperature? For example: Given $\Delta G = -230 Kcal/mol$ at $773K$ for the reaction $4/3Al + O_2 > 2/3Al_2O_3$, find the Gibbs energy at $573K$
With that data I can only think of doing $(-230*573)/773$... |
I have been trying to solve this problem
[![enter image description here][1]][1]
Part a) can be proved using the formula [![enter image description here][2]][2].
For part b), the expectation value of the potential energy can be calculated from the integral
[![enter image description here][3]][3],
where ... |
Hydrocortisone Cream seems to be sold as 1% w/w but my cream is 1% m/m which is confusing are they the same units or the same concentrations? |
Is 1% m/m the same as 1% w/w? |
Hydrocortisone cream seems to be sold as 1% w/w, but my cream is 1% m/m, which is confusing. Are they the same units or the same concentrations? |
I am studying the very BASIC introduction of catalysis in general chemistry and encountered an example of a heterogeneous catalyst, which is catalytic hydrogenation of alkene into alkane using Pt/C or Pd/C, I have some questions:
1. why sometimes we need to use Pt, and sometimes we need to use Pd? Are there any diff... |
My sir gave us a compound:
CH3CH(OH)CH(Br)CH(OH)CH3
And he told us the middle carbon is chiral being a recorded class I was not able ask him this question .
Since there are two identical groups around it I would guess it should not be chiral
Has he made and error ?
|
How is this carbon chiral? |
My teacher told us the middle carbon in 3‐bromopentane‐2,4‐diol is chiral:
$$\ce{CH3-CH(OH)-\overset{\star}{C}H(Br)-CH(OH)-CH3}$$
Since there are two identical groups around it, I would guess it should not be chiral.
It was a pre-recorded class and I was not able ask this question. Has my teacher made a mistak... |
How is the central carbon in 3‐bromopentane‐2,4‐diol chiral? |
Are there any tables with empirical equations to calculate properties of air as a function of a temperature at 1 atm?
For example, NIST provides such equations for a large number of gases, but I was not able to find such solution for air, where I would specifically like to obtain:
- Dynamic viscosity,
- Speci... |
From my understanding, if you were to look at a pressure-volume graph of a reversible, isothermal expansion, the area under it would represent reversible work. Similarly, if you were to graph an irreversible, isothermal expansion on top of this graph, you’d see a smaller rectangular area representing the irreversible w... |
How does an irreversible process maintain internal energy while dissipating excess heat? |
First, let's debunk a commonly taught myth, which is that the bonding in $\ce{SF6}$ involves promotion of electrons to the 3d orbitals with a resulting $\mathrm{sp^3d^2}$ hybridisation. **This is not true.** Here's one reference: [*J. Am. Chem. Soc.* **1986,** *108,* 3586](http://pubs.acs.org/doi/abs/10.1021/ja00273a00... |
**TL;DR** Fluorine is electronegative and can support the extra negative charge that is dispersed on the six X atoms in $\ce{SX6}$, whereas hydrogen cannot.
-----
First, let's debunk a commonly taught myth, which is that the bonding in $\ce{SF6}$ involves promotion of electrons to the 3d orbitals with a resulting... |
From [Wikipedia](https://en.wikipedia.org/wiki/Aluminium_isopropoxide#Structure):
> A tetrameric structure of the crystalline material was verified by NMR spectroscopy and X-ray crystallography. The species is described by the formula $\ce{Al[(μ-O-i-Pr)2Al(O-i-Pr)2]3}$. The unique central $\ce{Al}$ is octahedral, an... |
**TL;DR** Fluorine is electronegative and can support the extra negative charge that is dispersed on the six X atoms in $\ce{SX6}$, whereas hydrogen cannot.
-----
First, let's debunk a commonly taught myth, which is that the bonding in $\ce{SF6}$ involves promotion of electrons to the 3d orbitals with a resulting... |
An oxidizing agent pulls the electron cloud of the substance being oxidized towards itself, for example:
$$\ce{F2 + 2 X- -> 2F- + X2}\qquad (\ce{X} = \ce{Cl}, \ce{Br}, \ce{I})$$
We also know that fluorine has very high charge/mass ratio as it is very small in size and its electron gain enthalpy is know to be ver... |
[![enter image description here][1]][1]
In a zinc-copper voltaic cell,
What causes the initial electron movement from the zinc to the copper?
I understand that copper would pull the electrons more strongly than zinc, but only if it is electron deficient. Both half cells of the voltaic cell are electrically... |
I am studying the very BASIC introduction of catalysis in general chemistry and encountered an example of a heterogeneous catalyst, which is catalytic hydrogenation of alkene into alkane using Pt/C or Pd/C, I have some questions:
1. why sometimes we need to use Pt, and sometimes we need to use Pd? Are there any diff... |
Why is boiling point of Ammonia greater than Arsine? |
An acid/base nwutralization will create a salt + water. If one uses water itself as the acid or base, and have an acid/base neutralization, how come that doesn't create a salt?
For example:$$ HCN (aq) + H_2O(aq) = H_3O^+ + CN^- = H_3OCN$$
Why doesn't that happen? What is keeping those conjugate bases and acids f... |
Why doesn't base/acid reacting with water create a salt? |
What starts the reaction in a voltaic cell? |
For both electrodes, regardless of their galvanic connection, are ongoing the opposite processes
$$\ce{M(s) <=> M^n+(aq) + n e-}$$.
The forward process charges the electrode negatively, but slows down at more negative potentials.
The backward process charges the electrode positively, but slows down at more po... |
I've learned that HCl escapes HDPE. I looked up why and it turns out it's because of the small size of the molecule. That factor is unlikely to be affected by the concentration of HCl in water, but I was thinking: does water exert an "attractive" effect on HCl such that HCl would escape an HDPE container from a solutio... |
An acid/base nwutralization will create a salt + water. If one uses water itself as the acid or base, and have an acid/base neutralization, how come that doesn't create a salt?
For example:$$ \ce{HCN(aq) + H2O(aq) <<=> H3O+ + CN- ->[??] H3OCN}$$
Why doesn't that happen? What is keeping those conjugate bases and ... |
For both electrodes, regardless of their galvanic connection, are ongoing the opposite processes
$$\ce{M(s) <=> M^n+(aq) + n e-}$$.
The forward process charges the electrode negatively, but slows down at more negative potentials.
The backward process charges the electrode positively, but slows down at more po... |
Why does the infrared spectrum of HCl only have one peak? |
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