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Is it possible to use the laws of termodynamics for non-ideal systems? |
The above reasons to use LLE are focused on the compound thermal similarities and instabilities.
But it does not take into the account the amount of compounds. While distillation separation can be great for major components, it may fail for minor one, and definitely for trace ones.
The LLE is frequently used for ... |
Topic: Chemical Bonding (Application of Bent's Rule)
> Bent's rule is also consistent with Gillespie's VSEPR model, and may provide alternative rationalisation for effect of electronegativity. So it is restated as: '*more electronegative atom not only prefers to stay in the orbital having more $\mathrm{p}$ character b... |
After the edits by the original post, the OP clarified that they used a hypochlorite (not an oxygen bleach as stated earlier) and left a piece of steel wool in it. Due to corrosive nature of chloride/hypochlorite, the steel wool crumbled to iron (III) oxides. When you gently heat rust in highly alkaline medium in the p... |
After the edits by the original post, the OP clarified that they used a hypochlorite (not an oxygen bleach as stated earlier) and left a piece of steel wool in it. Due to corrosive nature of chloride/hypochlorite, the steel wool crumbled to iron (III) oxides. When you gently heat rust in highly alkaline medium in the p... |
Quoting a reddit post from chemist [nallen](https://www.reddit.com/r/askscience/comments/2h4inh/why_does_shampoo_lather_less_in_dirty_hair_than/ckpggdo/):
The short answer is that the dirt and oils from your hair compete for the surfactants making them less available to form lather, which is small bubbles.
To bet... |
This is balanced equation of fermentation of glucose:
$$\ce{C6H12O6(aq) -> 2C2H5OH(aq) + 2CO2(g)}$$
I know that the result of glucose fermentation is ethanol ($\ce{C2H6O}$). What represented in the aforementioned equation is slightly different. I would like to know what $\ce{C2H5OH}$ is?
What is the OH functi... |
I was reading about different types of radius existing between atoms. It was written that If any atom can possess all the three types of radius, then van der Waals radius will be greater than metal... |
I've been looking at instructions on how to get lanolin from fleece and a lot of the instructions mention that adding salt to the water before distillation will increase the lanolin yield. Why is this?
I would think that the distillation would separate the water but not the salt leaving the lanolin contaminated with... |
Why does adding salt to water help distillation? |
I was reading about different types of atomic radius. It was written that if any atom can possess all the three types of radius, then van der Waals radius will be greater than metallic radius. Howe... |
The paragraph you cite does not define Bent's rule (see [What is Bent's rule?](https://chemistry.stackexchange.com/q/15620/4945), [Utility of Bent's Rule - What can Bent's rule explain that other qualitative considerations cannot?](https://chemistry.stackexchange.com/q/15671/4945)).
If you compare $\ce{H3CCl}$ and ... |
The above reasons to use LLE are focused on the compound thermal similarities and instabilities.
But it does not take into the account the amount of compounds. While distillation separation can be great for major components, it may fail for minor one, and definitely for trace ones.
The LLE is frequently used for ... |
What is the mechanism for trans-stilbene to stilbene dibromide?
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/IVSzx.png |
What is the mechanism for trans-stilbene to stilbene dibromide? |
I'm new to VASP and as such don't know much of its intricacies yet. I want to find out the interlayer binding energy of a given molecule and to do that I already opted for the use of different functionals (DFT-D3, SCAN, etc.) to find the total energy of my system in case of the bulk material and in case of the isolated... |
How to do RPA (Random Phase Approximation) in VASP? |
Given their places on the periodic table I'd assume Aluminium has a higher ionization energy, because it has fewer energy levels, and is on a "righter" row on the periodic table, but in reality it is the opposite. Does anyone here know why? |
Why does Calcium have a higher ionization energy than Aluminium? |
[NIST Webbook Chemistry][1] is a reference which I would recommend as a first (as in *initial*) resource to consult for enthalpies of small organic molecular and inorganic materials. The entry about [methanol][2] lists for one temperature the value in question, the experimental method of acquisition, and the primary l... |
I've noticed that in most papers the interlayer binding energy is given in units of $meV/A$ (A being Angström, can't seem to get it shown here). But how do I get these units? Do I divide the interlayer binding energy I get by the area of my unit cell? |
Interlayer binding energy - how to convert to $meV/A^2$? |
I've noticed that in most papers the interlayer binding energy is given in units of meV/Ų. But how do I get these units? Do I divide the interlayer binding energy I get by the area of my unit cell? |
Interlayer binding energy: how to convert to meV/Ų? |
H-NMR with 10H integration? |
Good question. We frequently "salt out" semi-soluble organic compounds from water because the ionic nature of the salt is more compatible with the water and less compatible with the (less ionic) organic compound. This is used, for instance, to drive sodium stearate (soap) from water. Adding salt could help drive more l... |
I just had a question about molecular orbitals. I was just wondering if the energies of the LUMO (virtual orbitals) derived from CCSD(T)/cc-pTVZ calculations could be trusted. I remember reading some time ago that these orbital energies could not be trusted since they contained no electrons. If they cannot be trusted, ... |
Hi, I have a question regarding my university assignment. In this case; it’s medroxyprogesterone. We all know that it’s a hydrophobic drug, hence, we are assigned to create a sterile injection in aqueous formulation. Aqueous means it has to be solu... |
I have a question regarding the stepwise stability constants of metal complex formation/substitution.
My lecture notes say that if we have a metal complex, say $[MX_{6}]$, and a substitution reaction $[MX_{6}] + L\longrightarrow [MX_{5}L]+X$ with equilibrium constant $K_{1}$, and 5 other equilibrium constants $K_{2... |
Why do statistical effects impact stepwise stability constants? |
When thinking about orbital energy levels, it is not a good idea to think of them as fixed energy 'levels' that can be filled with electrons. This kind of picture is often found in introductory textbooks, but it is wrong. For example, it is known that even for the Hartree-Fock theory, the energy of a molecule is not a ... |
What is the mechanism for trans-stilbene to stilbene dibromide?
This is what I know:
The bond between the hydrogen and bromine is broken and the bromine is given a negative charge while the h protonates the double bond between the two Ph groups. After that, I am unsure what the H2O2 does
[![enter image descriptio... |
I read on my book this:
$$H_{2}SO_{3}+H_{2}O\rightarrow HSO_{3}^{-}+H_{3}O^{+}$$
while I rather would write (not balanced):
$$H_{2}SO_{3}+H_{2}O\rightarrow 2H^{+}+SO_{3}^{2-}+2H_{2}O\rightarrow SO_{3}^{2-}+2H_{3}O^{+}$$
I mean I don't understand why the book writes only a partial deprotonated acid. Someone could ex... |
I read in my book this:
$$\ce{H2SO3 + H2O -> HSO3- +H3O+}$$
while I rather would write (not balanced):
$$\ce{H2SO3 + H2O -> 2 H+ + SO3^2- + 2 H2O -> SO3^2- + 2H3O+}$$
I mean I don't understand why the book writes only a partial deprotonated acid. Someone could explain this? |
What is the mechanism for *trans*-stilbene to stilbene dibromide?
[![trans-stilbene to stilbene dibromide][1]][1]
This is what I know:
The bond between the hydrogen and bromine is broken and the bromine is given a negative charge, while the $\ce{H}$ protonates the double bond between the two $\ce{Ph}$ groups. ... |
>[![enter image description here][1]][1]
I got this data from an assignment problem. In the case of Copper it makes complete sense for the stability constant of formation of $\ce{[Cu(en)_3]^{2+}}$ to be that low given that we have $d^9$ configuration and strong Jahn Teller distortion leading to strain in the rings f... |
Should we expect Jahn Teller distortion in bis(ethylenediamine)nickel(II)? |
>[![enter image description here][1]][1]
I got this data from an assignment problem. In the case of Copper it makes complete sense for the stability constant of formation of $\ce{[Cu(en)_3]^{2+}}$ to be that low given that we have $d^9$ configuration and strong Jahn Teller distortion leading to strain in the rings f... |
So in a titration to decide the iron content of a pill we disolved the iron in Sulfuric acid and then titrated it with Cerium(IV)sulfate. But i just wondered whats wrong with using Nitric and Hydrochloric Acid in this scenario?
|
When disolving a iron pill for titration, why do i use Sulfuric acid instead of Nitric or Hydrochloric Acid? |
The key feature in the product that shows what is going on is the *trans* configuration of the two bromines. This is characteristic of the addition of elemental bromine *via* a brominium ion [mechanism here][1].
So where does the Br2 come from as we started with HBr? This is where the hydrogen peroxide comes in. It... |
I realize that there are exceptions but as a general rule of thumb, is an ion or a polar molecule attracted to water? I think that it would be ions since the charge is much larger than the net dipole of polar molecules but I can't find anything definitive regarding this. |
Is an ion or a polar molecule more attracted to water in general? |
I have been given a question that asks me to choose one that has the biggest ionization energy:
1. Br- and Kr
2. Cl- and Ar
3. Cl and Cl-
However, I am not sure how I can compare the ionization energy between an ion and an element? |
https://youtu.be/0F8cE4N42NQ
I understand that the anode can be oxidised but what is the reduction reaction at the cathode? They are using a salt water solution Na+ Cl- and a copper cathode.
Ered Cu=0.337
Ered Na=-2.71
Ered Al=-1.662
Thus we can see that the Al is oxidised but there are no Cu2+ ions to be reduce... |
What is the electrochemical reaction of this battery? |
Yes, in principle it could be different, but the effect would be very small unless the increase in pressure were very large.
Let's call your liquid "$X$". At equilibrium, the chemical potential of $X_{(l)}$ equals the chemical potential of $X_{(g)}$. The pressure of $X_{(g)}$ at which that occurs is called the va... |
> Thus we can see that the Al is oxidised but there are no Cu2+ ions to
> be reduced also Na+ reduction would lead to a negative Ecell standard
> and a positive Gibbs. Is it an air cathode where O2 is being reduced?
Well, there is no free lunch in this world. This is not a conventional cell in which each electrode... |
In a titration to decide the iron content of a pill we dissolved the iron in sulfuric acid and then titrated it with cerium(IV) sulfate. But I just wondered what's wrong with using nitric and hydrochloric acid in this scenario?
|
When disolving a iron pill for titration, why do I use sulfuric acid instead of nitric or hydrochloric acid? |
I've watched a YouTube video [Soda Can Battery - Power From Trash - DIY Project](https://youtu.be/0F8cE4N42NQ). I understand that the anode can be oxidised, but what is the reduction reaction at the cathode? They are using a salt water solution $\ce{Na+}$ $\ce{Cl-}$ and a copper cathode.
$$
\begin{array}{cc}
\hlin... |
Consider this positive result from the Lucas test (adding $\ce{ZnCl2/HCl}$ to a tertiary alcohol):
[![enter image description here][1]][1]
My question is quite straightforward but I can't find the answer. What is in the top layer (thin and clear) and what is in the bottom milky layer? Also, what is making it milky?... |
Why is the bottom white in a lucas test? |
I have a question regarding the stepwise stability constants of metal complex formation/substitution.
My lecture notes say that if we have a metal complex, say $\ce{[MX_{6}]}$, and a substitution reaction $\ce{[MX_{6}] + L -> [MX_{5}L]+X}$ with equilibrium constant $K_{1}$, and 5 other equilibrium constants $K_{2}$... |
>Which is more reactive towards Electrophilic Substitution, Cresol or Para-Cresol?
Both Oxygen and Methyl are activating group, I don't know on what basis do I compare their reactivity. There's just a change in the position of one of the group.
My book says Cresol is more reactive and the reason given was, "If t... |
Is Cresol or Para-Cresol more reactive towards Electrophilic Substitution? |
>Which is more reactive towards Electrophilic Substitution, Meta-Cresol or Para-Cresol?
Both Oxygen and Methyl are activating group, I don't know on what basis do I compare their reactivity. There's just a change in the position of one of the group.
My book says Meta-Cresol is more reactive and the reason given ... |
Is Meta-Cresol or Para-Cresol more reactive towards Electrophilic Substitution? |
Part of the Clapeyron equation involves replacing ∆S with ∆H/T. I can see the step from ∆S to ∆q/T but I'm not sure why you can replace ∆q with ∆H. From my understanding dH = dq +Vdp when assuming no work other than pv work is done. I don't understand how you can substitute ∆H for ∆q without assuming that the pressure ... |
Why when deriving the Clapeyron equation can you assume that ∆H = q, as surely the pressure is not constant? |
While finding the concentration of NaOH via titration with $0.05M$ Oxalic acid solution (in our lab) we put NaOH in the burette whereas added phenopthaline to oxalic acid in titration flask. But in [this](https://youtu.be/EJ_nSCNwqmg) video the demonstrator does just opposite ( i.e., NaOH in flak with phenopthaline). I... |
For performing an exploratory study, we need Ca/PO4/acetate solution containing 2mmol/L calcium, 2 mmol/L phosphate and 0.075 mol/L acetate at pH 4.5.
Can anybody help us with the method to prepare such a solution, if possible using compounds/mixtures available commonly in the market?
Will appreciate hints or p... |
Acid-base titration: Unknown base in burette or flask? |
Part of the Clapeyron equation involves replacing ∆S with ∆H/T. I can see the step from ∆S to ∆q/T but I'm not sure why you can replace ∆q with ∆H. From my understanding dH = dqv +Vdp when assuming no work other than pv work is done. I don't understand how you can substitute ∆H for ∆q without assuming that the pressure... |
Why when deriving the Clapeyron equation can you assume that ∆H = qp, as surely the pressure is not constant? |
Part of the Clapeyron equation involves replacing $\Delta S$ with $\Delta H/T$. I can see the step from $\Delta S$ to $\Delta q/T$ but I'm not sure why you can replace $\Delta q$ with $\Delta H$. From my understanding $\mathrm dH = \mathrm dq_V +V\mathrm dp$ when assuming no work other than $pV$ work is done. I don't u... |
> (ii) The stepwise stability constants of the following complexes in aqueous solution at $\pu{25 °C}$ are given below:
> $$
\begin{array}{cll}
\hline
\ce{M} & \ce{[M(en)2(H2O)2]^2+} & \ce{[M(en)3]^2+} \\
\hline
\ce{Cu} & \pu{1E9} & 0.1~\text{(estimated)} \\
\ce{Ni} & \pu{1E6} & \pu{1E4} \\
\hline
\end{array... |
Should we expect Jahn–Teller distortion in bis(ethylenediamine)nickel(II)? |
For performing an exploratory study, we need Ca/PO4/acetate solution containing 2mmol/L calcium, 2 mmol/L phosphate and 0.075 mol/L acetate at pH 4.5.
Can anybody help us with the method to prepare such a solution, if possible using compounds/mixtures available commonly in the market?
Will appreciate hints or poi... |
Why when deriving the Clapeyron equation can you assume that dH = dq, as surely the pressure is not constant? |
This question raises more important issues than just the technical "why methyl ester," so I'll address those too.
The easiest explanation for their focus on the methyl ester is that the ethyl ester just isn't nearly as sweet. [This report][1] says it is approximately $10\times$ less sweet (see Table VI on page 2689 ... |
> Thus we can see that the Al is oxidised but there are no Cu2+ ions to
> be reduced also Na+ reduction would lead to a negative Ecell standard
> and a positive Gibbs. Is it an air cathode where O2 is being reduced?
Well, there is no free lunch in this world. This is not a conventional cell in which each electrode... |
I want to ask a question about alkenes and their reactivity with acids.
From high school studies, I recall that if you had an acid $\ce{H3O+}$ i.e. $H^+$ that it would react with an alkene as shown below:
[![enter image description here][1]][1]
However, when I was given a lecture today on Allylic alcohols ... |
Calcium hydroxide is soluble in glycerol. Assuming anhydrous conditions, could such a solution be electrolysed to yield calcium metal, or would glycerol OH groups interefere with the process? |
Here the issue in question is about rate. Of course, in a real life scenario, both reactions probably take place, the question is which reaction is faster?
Well, looking at the reactants here, you are having a strong acid. The hydroxy group is way more basic/nucleophilic than the double bond simply due to electronic... |
I crushed my antibiotics (amoxicillin + potassium Clavulanate ). Does it deform in the stomach acid and therefore become useless ? Or does it has no effect and goes directly into the intestines and blood stream subsequently? |
Does Amoxcillin (as trihydrate) degrade in stomach acid? |
Can someone please help me out with this question? I know that I have to find Qsp and compare this to the Ksp given and if Qsp is bigger, then a precipitate will form. However, I do not know how to find Qsp when 2 substances are mixed together.
I also have the answer which is "YES, Q = 4.0 x 10-4 which is greater than... |
> $\pu{105 mL}$ of $\pu{0.10 M}$ $\ce{AgNO3}$ is added to $\pu{125 mL}$ of $\pu{0.35 M}$ $\ce{K2CrO4}.$ Will a precipitate form? $(K_\mathrm{sp}$ for $\ce{Ag2CrO4}$ is $\pu{1.12E-12}.)$
Answer:
>! Yes, $Q = \pu{4.0E-4}$ which is greater than $K_\mathrm{sp}.$
Can someone please help me out with this question? I... |
I need to find by how much the activation energy decreases when the rate constant increases by a '$x$' factor when a catalyst is used in the reaction.
I'm just super confused about how to solve this. Using Arrhenius relation I have
$$\frac{k_2}{k_1} = \frac{A\mathrm e^{-E_\mathrm{a2}/(RT)}}{A\mathrm e^{-E_\math... |
In the synthesis of DMAD, we eliminate two bromides from dibromosuccinic acid in basic environment to get acetylenedicarboxlyic acid (Step 2).
[![dmad][1]][1]
However, this reaction could also happen:
[![alternate_mech][2]][2]
The reaction in *Organic Syntheses* (http://www.orgsyn.org/demo.aspx?prep=cv2p0010) w... |
Why doesn't this reaction happen? |
[![enter image description here][1]][1]
[![enter image description here][2]][2]
The number of enolizable hydrogen atoms according to me is four, but the answer given for the question says it has seven enolizable hydrogens. Where are the rest of them?
[1]: https://i.stack.imgur.com/6pyUJ.jpg
[2]: https:/... |
I use a mineral based fertilizer in powder form which - according to the label - should not contain any fiber and is fully soluble in water.
The NPK + Mg + trace elements add up to about 60%.
What constitutes the rest? |
Shouldn't mineral NPK fertilizer ingredients add up to 100%? |
How to make copper salicylate with electrolysis? |
I use a mineral based fertilizer in powder form which - according to the label - should not contain any fiber and is fully soluble in water:
[![NPK fertilizer label][1]][1]
The NPK + Mg + trace elements add up to about 60%.
What constitutes the rest?
[1]: https://i.stack.imgur.com/UCzt4.jpg |
I use a mineral based fertilizer in powder form which - according to the label - should not contain any fiber and is fully soluble in water (I dissolved 2 times the recommend dosage and found no solids remaining in the solution):
[![NPK fertilizer label][1]][1]
The NPK + Mg + trace elements add up to about 60%.... |
I don't have a problem understanding the chemical mechanisms underlying freezing point depression or colligative properties in general, but what I cannot seem to grasp is how if you add salt to ice you end up with a salt-ice-water solution that is actually colder than the ice you started with.
Two other places on t... |
I don't have a problem understanding the chemical mechanisms underlying freezing point depression or colligative properties in general, but what I cannot seem to grasp is how if you add salt to ice you end up with a salt-ice-water solution that is actually colder than the ice you started with.
Two other places on t... |
**Phase change is not at constant temperature, phase equilibrium is**
>[OP] it's a phase transition so the temperature of the ice should remain constant
Here is a counter example: If you add ice cubes to hot water, the ice will melt, cooling down the hot water. In this system, there is no thermal equilibrium, so ... |
I am quite new to the field. So try to figure out what is meant by the equilibrium state of an electrochemical cell?
Is it, where both half cells passing the same number of electrons to either side? if yes, how do the electrons transfer during non-equilibrium state (is it like, there is a net electron transfer due ... |
I crushed my antibiotics (amoxicillin + potassium Clavulanate). Does it deform in the stomach acid and therefore become useless? Or does the acid have no effect and the amoxicillin goes directly into the intestines and blood stream subsequently? |
Does Amoxicillin (as trihydrate) degrade in stomach acid? |
In a particular question in one of my reference book, I was asked if the given compound (meso-butane-2,3-diol) was a meso compound or not. In it’s solution part, to show that the compound was actually meso, they did the following.
[![enter image description here][1]][1]
As I was not convinced about rotation of C2, ... |
Since glass is a mix of silicates of sodium and calcium produced by heating or fusing together $\ce{Na2O}$ (Lewis base) with sand or $\ce{SiO2}$ (Lewis acid). Since $\ce{Na2O/NaOH(aq)}$ is a strong base and is used to create water glass(es)$(\ce{Na2SiO3},$ $\ce{Na_xSiO_y}$ etc.).
Is there some procedure in place to ... |
My understanding is that disposable plastic water bottles should not be reused or used at all after some time, because the bottle will eventually leech microplastics into the water. Since coca cola is pretty acidic and can be used as toilet cleaner, doesn't that mean it would "dissolve" its contain bottle and get those... |
Why aren't plastic bottles of coca cola full of microplastics? |
First of all, it is useful to envision an adiabatic process: add ice at the normal melting temperature to water or cold brine slightly above the MP in a perfectly insulated container (zero heat transfer to the outside) at constant pressure. What do you expect to happen? If the salt concentration is nil (pure water) the... |
First of all, it is useful to envision an adiabatic process: add ice at the normal melting temperature to water or cold brine slightly above the MP in a perfectly insulated container (zero heat transfer to the outside) at constant pressure. What do you expect to happen? If the salt concentration is nil (pure water) the... |
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