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According to the CRC Handbook of Chemistry and Physics, melting point of $\ce{CaF2}$ is $\pu{1418 ^\circ C}$, of $\ce{Al2O3}$ (in its corundum form) is $\pu{2053 ^\circ C}$, and of $\ce{Na3AlF6}$ is $\pu{1009 ^\circ C}$ (lowest of the all three). Thus the cryolite should melt first.
I have read mentions of the prob... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/YRs49.jpg
For side chain oxidation of benzene, a benzylic hydrogen is required. But, for this compound the top branch connected to the benzene ring does not have a benzylic hydrogen. So, will the top branch be broken off in the process of ... |
In quantum mechanics, in the 'particle in a box' topic, I studied that by solving the Schrödinger equation, we can actually find out what the wave function of the particle in a box looks like. Corresponding to different energy levels, the particle can have different wave functions. For e.g., in it's ground state (lowes... |
In quantum mechanics, in the 'particle in a box' topic, I studied that by solving the Schrödinger equation, we can actually find out what the wave function of the particle in a box looks like. Corresponding to different energy levels, the particle can have different wave functions. For e.g., in it's ground state (lowes... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/YRs49.jpg
For side chain oxidation of benzene, a benzylic hydrogen is required. But, for this compound the top branch connected to the benzene ring does not have a benzylic hydrogen. So, will the top branch be broken off in the process of ... |
I realize that *n*-factor is an outdated concept however I am interested in its formal definition when it was introduced.
We have many definitions now on how to calculate *n*-factor depending on the type of reaction and compounds involved.
> 1. For acids, n-factor is defined as the number of H+ ions replaced by ... |
The definition of n-factor, what was it when it was introduced? |
[![ 4‐ethyl‐1,1‐dimethyl‐3,4‐dihydro‐2H‐naphthalene][1]][1]
Benzylic hydrogen is required for the side chain oxidation of benzene. But for this compound the top branch connected to the benzene ring does not have a benzylic hydrogen. So, will the top branch be broken off in the process of oxidation?
The reagents a... |
What product will be formed from the side chain oxidation of 4‐ethyl‐1,1‐dimethyl‐3,4‐dihydro‐2H‐naphthalene? |
My professor mentioned that borazine is aromatic, but not as much as, say, benzene. The reason he gave for this was that the B-N bonds in borazine, being polar, inhibit resonance. He also mentioned that the same inhibition of resonance occurs in h-BN. Why is this so? What difference does bond polarity make? |
Why is the polarity of the B-N bonds in borazine the reason for its reduced delocalisation of π electrons? |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/nZWbc.png
How are the bridge bonds different from any other bonds in $Al_2Cl_6$. We could have just mentioned the other bond formed by $Cl$ as a coordinate bond. Why introduce this extra concept? I can understand why 3 centred-2 electron bon... |
How are 3 centred-4 electron bonds any different from 2 centred-2 electron bonds? |
> $$\ce{CH3OH(g) + NOCl(g) <=> CH3ONO(g) + HCl(g)}$$
> The volume of the container is $\pu{433 cm^3},$ $T = \pu{50 °C}.$ Methanol was added until the pressure was $\pu{50.1 mbar},$ then $\pu{0.059 g}$ of $\ce{NOCl}$ was added. At equilibrium the partial pressure of $\ce{NOCl}$ is $\pu{27.6 mbar}.$
> Calculate $K.$
... |
What effect does temperature have on endothermic and exothermic reversible reactions? Please also explain the reason why it responds like this.
And what do people mean when they say something like "increasing pressure or volume shifts the reaction to left/right"? What do people mean by "left/right reaction shift"?
|
I read a problem which was as follows
> Equal volumes of 1M H3PO4 and 1M Na3PO4 are mixed. The pH of the resultant mixture is (along with this ka1,ka2,ka3 of the acid were mentioned)
The way I approached this problem was as follows:
$ka1 = \frac{[\ce{H2PO4^-}][\ce{H^+}]}{[\ce{H3PO4}]}$, similarly $ka2 = \frac{[\... |
[![Dimer of Aluminum Chloride][1]][1]
[1]: https://i.stack.imgur.com/nZWbc.png
How are the bridge bonds in $\ce{Al2Cl6}$ different from the terminal bonds?
We could have just mentioned the bridge bond formed by $\ce{Cl}$ as a coordinate bond. Why introduce this extra concept?
I can understand why 3 cent... |
How are 3 center-4 electron bonds any different from 2 center-2 electron bonds? |
In quantum mechanics, in the 'particle in a box' topic, I studied that by solving the Schrödinger equation, we can actually find out what the wave function of the particle in a box looks like. Corresponding to different energy levels, the particle can have different wave functions. For e.g., in it's ground state (lowes... |
I think this resembles the question [Confused about strong/weak dibasic and tribasic acids?][1]
Saying that the degree of dissociation $(\alpha)$ of citric acid is greater because its triprotic is not correct. The degree of dissociation should be calculated for each dissociation separately. The degree of dissociatio... |
Since the solution will be acid in water, the $\mathrm{pH}$ will be below all the $\mathrm{p}K_\mathrm{a}$ values.
Given that the $\mathrm{pH}$ is below all the $\mathrm{p}K_\mathrm{a}$ values, an upper limit is that the second $\mathrm{p}K_\mathrm{a}$ will contribute $10^{(3.09-4.75)} = 0.022$ protons for each pr... |
I have a question on the basics of DFT, which bases on the Hohenberg-Kohn theorem: there exist an unique mapping between the external potential, the electronic wave function and thus also the electronic density n(r). In other words, from [wikipedia][1], where ${\displaystyle v(\mathbf {r} )}$ is defined as an external ... |
I read a problem which was as follows:
> Equal volumes of $\pu{1M} \ \ce{H3PO4}$ and $\pu{1M} \ \ce{Na3PO4}$ are mixed. The $\mathrm{pH}$ of the resultant mixture is (along with this $K_\mathrm{a1}, K_\mathrm{a2}, K_\mathrm{a3}$ of the acid were mentioned)
The way I approached this problem was as follows:
$K_\ma... |
Is there a term that fills in the blank of "X is a _______ of Y" which means "X is in the same group of the periodic table as Y"? |
What is the name for the relationship between two elements in the same group? |
I read a problem which was as follows:
> Equal volumes of $\pu{1M} \ \ce{H3PO4}$ and $\pu{1M} \ \ce{Na3PO4}$ are mixed. The $\mathrm{pH}$ of the resultant mixture is (along with this $K_\mathrm{a1}, K_\mathrm{a2}, K_\mathrm{a3}$ of the acid were mentioned)
The way I approached this problem was as follows:
$K_\ma... |
Is there a term that fills in the blank of "X is a _______ of Y" which means "X is in the same group of the periodic table as Y"?
This is not a homework question. I searched around a bit on google and could not find an answer. |
***Background:***
I am a mathematician with very little knowledge in chemistry (I do know some
physics). I will probably teach a course "mathematics for (1st year) chemistry
students" in the future (1st semester 3h + 1h exercises per week, 2nd semester
2+1h). This will be the only (mandatory) mathematics course in ... |
If cell operates reversibly than change in Gibbs energy of system equals electrical work of the cell. As far as I know electrical work is work done by electric field when charge moves between certain potential difference which in case of electrochemical cells is potential difference between two electrodes: $$ W = -zF\D... |
What Does Electrical Work Represent in Context of Electrochemical Cells? |
I'm looking for a specific term which can be used to describe two elements in the same group of the Periodic Table. This would be useful since elements in the same group tend to have similar chemical/physical properties.
For example, is there a word that could fill in the blank: *"X is a _______ of Y"*, where X and ... |
***Background:***
I am a mathematician with very little knowledge in chemistry (I do know some
physics). I will probably teach a course "mathematics for (1st year) chemistry
students" in the future (1st semester 3h + 1h exercises per week, 2nd semester
2+1h). This will be the only (mandatory) mathematics course in ... |
There is a solubility chart in my college chemistry class text for "Solubility of Ionic compounds in water". I have copied and pasted image of chart below. I was surprised to find a dozen ionic compounds marked "--" meaning "no data".
[![ionic compounds solubility chart][1]][1]
Among the entries marked "no dat... |
I am studying conformational analysis of monosubstituted cyclohexane. "A-value" refers to the energy difference between conformers with substitutent in equatorial (more favored) and axial positions. A higher A-value means that the axial conformer will more readily convert to equatorial.
According to [Wikipedia](http... |
Why is the A-value of methoxy group lower than that of the hydroxyl group? |
While reading about Ellingham diagram in my textbook, I noticed that for:
$\ce{C_(_s_) + O_2_(_g_) -> CO_2_(_g_)}$,
the standard Gibbs free energy ($\ce{Δ_fG^°}$) doesn't seem to vary with temperature (I even compared the line's inclination with a horizontal line and they coincided completely!).
Going throu... |
Why is the formation free energy of carbon dioxide almost constant in Ellingham diagrams? |
While reading about Ellingham diagram in my textbook, I noticed that for:
$\ce{C_(_s_) + O_2_(_g_) -> CO_2_(_g_)}$,
the standard Gibbs free energy ($\ce{\Delta_fG^\circ}$) doesn't seem to vary with temperature (I even compared the line's inclination with a horizontal line and they coincided completely!).
Go... |
While reading about Ellingham diagram in my textbook, I noticed that for:
$\ce{C_(_s_) + O2_(_g_) -> CO2_(_g_)}$,
the standard Gibbs free energy ($\ce{\Delta_fG^\circ}$) doesn't seem to vary with temperature (I even compared the line's inclination with a horizontal line and they coincided completely!).
Goin... |
Structural isomerism is categorised into 5 main types; which are listed from highest priority to lowest as:
1. Tautomerism
2. Functional isomerism
3. Metamerism- Metamerism is a type of structural isomerism where the length of the carbon-side chain attached to a **polyvalent** functional group( here ether is th... |
Structural isomerism is categorised into 5 main types; which are listed from highest priority to lowest as:
1. Tautomerism
2. Functional isomerism
3. Metamerism- Metamerism is a type of structural isomerism where the **carbon-side chain/ alkyl group** attached to a **polyvalent** functional group differs( here ... |
Is this correct so far? Is there any other way to do this? Was it wrong of me to add KCN instead of HCN? Any help would be appreciated, thank you!
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/wvT6Z.png |
Starting from any a,ß-unsaturated carbonyl compound, how would you prepare the following Organic compound? |
The list of topics will be infinite (if that is allowed in mathematics) if you keep on thinking what chemistry students *must* know. This should not be the goal of this course to superficially glance over all the possible advanced and superadvanced topics which a chemist may encounter in his MSc/PhD.
We should keep... |
The list of topics will be infinite (if that is allowed in mathematics) if you keep on thinking what chemistry students *must* know. This should not be the goal of this course to superficially glance over all the possible advanced and superadvanced topics which a chemist may encounter in his MSc/PhD.
We should keep... |
If your sample is solid *and* crystalline, knowledge of the unit cell's dimension and symmetry (e.g., fcc) and density allows you to determine the molecular mass of your compound.
In fact, in crystallography, you may determine the macroscopic density of your sample (e.g., find a liquid which *i*) wets your crystals ... |
It depends on what you define as a bond. A three-center two electron bond is in general stronger than an ordinary two-center bond because delocalizing the bond over three atoms instead of two makes the bonding MO more stable. But, the bridge bond is also shared between two linkages so each individual linkage has less... |
The list of topics will be infinite (if that is allowed in mathematics) if you keep on thinking what chemistry students *must* know. This should not be the goal of this course to superficially glance over all the possible advanced and superadvanced topics which a chemist may encounter in his MSc/PhD.
We should keep... |
The definition of the **primary quantum yield** given in Atkins as "The primary quantum yield, φ, is defined as the number of photophysical or photochemical events that lead to primary products divided by the number of photons absorbed by the molecule in the same interval."
And from Wiki: The general definition of t... |
What is the difference between "primary quantum yield" and quantum yield? |
The definition of the **primary quantum yield** given in Atkins textbook Physical chemistry as "The primary quantum yield, φ, is defined as the number of photophysical or photochemical events that lead to primary products divided by the number of photons absorbed by the molecule in the same interval."
And from Wiki:... |
If we take the example of salicylic acid, hydrogen bonding is present in the acid as:
[![enter image description here][1]][1]
Even after deprotonation, it has intramolecular hydrogen bonding as:
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/XDyQw.jpg
[2]: https://i.stack.im... |
Why hydrogen bonding in some acids make them a stronger acid when it is present even before deprotonation? |
When NaCl is added to water, it dissociates into $\rm{Na^+}$ and $\rm{Cl^-}$. The newly formed $\rm{Na^+}$ and $\rm{Cl^-}$ do not react with water.
When $\rm{CH_3COONa}$ (sodium acetate) is added to water, it dissociates into $\rm{CH_3COO^-}$ and $\rm{Na^+}$. The newly formed $\rm{CH_3COO^-}$ reacts with water to fo... |
Why does acetate ion react with water? |
If we take the example of salicylic acid, hydrogen bonding is present in the acid as:
[![enter image description here][1]][1]
Even after deprotonation, it has intramolecular hydrogen bonding as:
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/XDyQw.jpg
[2]: https://i.stack.im... |
If we take the example of salicylic acid, hydrogen bonding is present in the acid as:
[![enter image description here][1]][1]
Even after deprotonation, it has intramolecular hydrogen bonding as:
[![enter image description here][2]][2]
# My doubt: #
>⚫ __p-hydroxybenzoic acid__(pKa=4.54) is less acidic ... |
In case of oxides of 15th group elements in form of M2O3 (M is the 15th group element), does oxidising power of oxides increase or decrease down the group?
I tried to check by comparing the SRP values or other related issues but didn't find any reliable sources.
Thank you in advance. |
As known aqua regia can't dissolve $\ce{Ag}$ because formation of $\ce{AgCl}$ precipitate. Similaraly will aqua regia precipate $\ce{Pb}$ as $\ce{PbCl2}$? **OR** It is not possible to obsverve this because aqua regia produce heat keeping solution warm ($\ce{PbCl2}$ is soluble in hot water). |
Can aqua regia/royal water dissolve lead? |
If we take the example of salicylic acid, hydrogen bonding is present in the acid as:
[![enter image description here][1]][1]
Even after deprotonation, it has intramolecular hydrogen bonding as:
[![enter image description here][2]][2]
# My doubt: #
__*p*-hydroxybenzoic acid__($\mathrm pK_\mathrm a = 4... |
Can aqua regia/royal water be produced with sources of chloride and nitrate other than hydrochloric acid and nitric acid? |
Yes, aqua regia can dissolve lead metal. From [here][1]:
> When we are working with an acidic chloride solution, like HCl (with
> an oxidizer) or **aqua regia, most of the lead will become an insoluble
> lead chloride** which if it is left to settle can be removed by careful
> decanting of the solution and filter... |
> 1. What metals (elemental, forget alloys) are neither attacked by nor dissolved in (freshly prepared) aqua regia?
[Wikipedia article of aqua regia][1] gives the answer (thanks to @Ian Bush):
> However, aqua regia does not dissolve or corrode silver, titanium,
> iridium, ruthenium, rhenium, tantalum, niobium, h... |
As known aqua regia can't dissolve $\ce{Ag}$ because formation of $\ce{AgCl}$ precipitate. Similarly will aqua regia precipitate $\ce{Pb}$ as $\ce{PbCl2}$? **OR** It is not possible to observe this because aqua regia produce heat keeping solution warm ($\ce{PbCl2}$ is soluble in hot water).
My question is clearly su... |
Aqua regia doesn't actually dissolve lead metal. It converts to insoluble lead salt. From [here][1]:
> When we are working with an acidic chloride solution, like HCl (with
> an oxidizer) or **aqua regia, most of the lead will become an insoluble
> lead chloride** which if it is left to settle can be removed by car... |
In case of oxides of 15th group elements in form of $\ce{M2O3}$ ($\ce{M}$ is the 15th group element), does oxidising power of oxides increase or decrease down the group?
I tried to check by comparing the standard reduction potential (SRP) values or other related issues but didn't find any reliable sources.
|
As known aqua regia can't dissolve $\ce{Ag}$ because formation of $\ce{AgCl}$ precipitate. Similarly will aqua regia precipitate $\ce{Pb}$ as $\ce{PbCl2}$? **OR** It is not possible to observe this because aqua regia produce heat keeping solution warm ($\ce{PbCl2}$ is soluble in hot water).
|
> 1. What metals (elemental, forget alloys) are neither attacked by nor dissolved in (freshly prepared) aqua regia?
At normal condition, most of the metals are impervious to aqua regia but if the conditions are changed like temperature, pressure, acid concentration or state of metal, they can be prone to attack.
... |
In my textbook, the following information is given about Ellingham diagram:
> The interpretation of $\ce{\Delta_rG^\circ}$ is based on ${K}$ ($\ce{\Delta G^\circ = -RTlnK}$). Thus it is presumed that the reactants and products are in equilibrium:
>
>$\ce{M_xO + A_r_e_d <=> xM + A_r_e_dO}$
>
>**This is not always... |
How can rearrangement happen in this case a non classical carbocation won't form? |
[![enter image description here][1]][1]
I am stuck at the point if a non classical carbocation should be formed on the 2nd Carbon of the side chain.
One of my friend gave me the following suggestion:
I guess $\ce{ICl}$ will break in the form $\ce{I+/Cl⁻}$ so considering this if $\ce{I+}$ gets attached to th... |
Does rearrangement take place in the reaction between ethenylcyclohexane and iodine chloride? |
If you Google "largest known cycloalkane", you will find this result:
[![enter image description here][1]][1]
For context, there has been discussions on "largest known alkane". There is [a related chem.SE question][2]. There is also a [scientific paper on it. The paper says that the longest linear alkane is $\ce{... |
Does the largest known cycloalkane contain 288 carbon atoms? |
It depends on what you define as a bond. A three-center two electron bond is in general stronger than an ordinary two-center bond because delocalizing the bond over three atoms instead of two makes the bonding MO more stable. But, the bridge bond is also shared between two linkages so each individual linkage has less... |
According to [*Makromol. Chem., Rapid Commun.* **1985,** *6* (3), 203–208](https://doi.org/10.1002/marc.1985.030060316)<sup>[1]</sup>, a paper by Kwang Sup Lee and Gerhard Wegner on the synthesis of $n>100, \ce{C_nH_{2n}}$ cyclo-alkanes and linear alkanes were successfully able to synthesis a linear alkane of $\ce{C38... |
It depends on what you define as a bond. A three-center two electron bond is in general stronger than an ordinary two-center bond because delocalizing the bond over three atoms instead of two makes the bonding MO more stable. But, the bridge bond is also shared between two linkages so each individual linkage has less... |
According to [*Makromol. Chem., Rapid Commun.* **1985,** *6* (3), 203–208](https://doi.org/10.1002/marc.1985.030060316)<sup>[1\]</sup>, Kwang Sup Lee and Gerhard Wegner, attempting the synthesis and study of $n>100, \ce{C_nH_{2n}}$ cyclo-alkanes and linear alkanes, were successfully able to synthesis a linear alkane of... |
When hf ≥ work function, Then the electron still comes out. So, if I say kinetic energy of ejected electron = 0, it should still come out. Right ?
Then, how does the electron even move out or gets ejected if its $v=0$? |
$\pu{48g}$ of graphite and $\pu{16g}$ of $\ce{O2}$ is given. The question is to count the no of molecules of $\ce{CO2}$ produced?
Now, the solution in book is this
No of $\ce{C}$ atoms = $\frac{\pu{48g}}{\pu{12g}}$ = $\pu{4mol}$. No of $\ce{O}$ atoms = $\frac{16}{16}$ =$\pu{1 mol}$ , and no of $\ce{O2}$ atoms = $... |
Some of the conformers of salicylic acid are given below, all of which are conformers planar in configuration.$\mathrm{^{[1]}}$
[![enter image description here][1]][1]
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/hmUjc.jpg
[2]: https://i.stack.imgur.com/PZ3pam.jpg
Although... |
Some of the conformers of salicylic acid are given below, all of which are conformers planar in configuration.$\mathrm{^{[1]}}$
[![enter image description here][1]][1]
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/hmUjc.jpg
[2]: https://i.stack.imgur.com/PZ3pam.jpg
Although... |
We know, solutes dissolved in water increases the boiling point of water. This question is an MCQ. The options are 96,99,100,104 degree Celsius. The correct answer is 96. Why? If the boiling point INCREASES after adding salt then why not 104? |
At which temperature does a concentrated aqueous solution of sodium chloride begin to boil? |
[![enter image description here][1]][1]
I am stuck at the point if a non classical carbocation should be formed on the 2nd Carbon of the side chain.
One of my friend gave me the following suggestion:
I guess $\ce{ICl}$ will break in the form $\ce{I+/Cl-}$ so considering this if $\ce{I+}$ gets attached to th... |
If your sample is solid *and* crystalline, knowledge of the unit cell's dimension and symmetry (e.g., fcc) and density allows you to determine the molecular mass of your compound.
In fact, in crystallography, you may determine the macroscopic density of your sample (e.g., find a liquid which *i*) wets your crystals ... |
Two rigid tanks are connected by a valve. Tank A contains 0.2 m^3 of water at 400 kPa an 80% quality. Tank B contains 0.5 m^3 of water at 200 kPa and 250 C. The valve is now opened, and the two tanks eventually come to the same state. Determine the pressure and the amount of heat transfer when the system reaches therma... |
If we look at system at constant temperature and volume which is galvanic cell, first law of thermodynamics states: $$ dU = dQ + dW'$$
Where W' is electrical work done by galvanic cell and Q is heat exchanged with surroundings.
As far as I know electrical work is work done by electric field when charge moves betw... |
Why Does Electrical Work Cause Changes in Internal Energy of the System? |
> Two rigid tanks are connected by a valve. Tank A contains $0.2\ \mathrm{m^3}$ of water at $400\ \mathrm{kPa}$ and $80\ \%$ quality. Tank B contains $0.5\ \mathrm{m^3}$ of water at $200\ \mathrm{kPa}$ and $250\ \mathrm{^\circ C}$. The valve is now opened, and the two tanks eventually come to the same state. Determine ... |
I'm kind of confused on how to distinguish the terms anode and cathode from oxidizer and reducer or oxidizing agent and reducing agent. Some references prefer to use one over the other in discussions depending on the topic. Are they suppose to mean the same thing in some cases? Like an anode has oxidation taking place ... |
What are the similarities / differences between the terms anode / cathode and oxidizing agent / reducing agent? |
In my book, it is written that:
$κ_{electrolytic solution} = κ_{electrolyte} + κ_{solvent}$
$G_{electrolytic solution} = G_{electrolyte} + G_{solvent}$
Where $κ$ and $ G$ are conductivity and conductance respectively. But why are conductance and conductivity additive in nature? Why is it that we can simply add c... |
Why are conductance and conductivity additive in nature? |
Rearrangement of cycloheptatrienyl carbene yields heptafulvene *via* a hydrogen shift.
[![Heptafulvene from Rearrangement of cycloheptatrienyl carbene][1]][1]
I see that the reaction is favorable because there is a conjugative effect with the $\pi$ system of the ring in the product.
Does this rearrangement hap... |
>What would be the wave function of the lowest energy molecular orbital of a hypothetical linear $\ce{H3+}$ molecule?
According to the LCAO method, I feel the lowest energy MO will be $\mathrm{1s(A) + 1s(B) + 1s(C)}$, where e.g. $\mathrm{1s(A)}$ is the wave function of the $\mathrm{1s}$ orbital of one of the Hydrog... |
There are some different applications.
For one, it tells you how many times an acid can lose a proton. For instance, you can have a diprotic ("with $\ce{2 H+}$") molecule, with $n=2$. For instance, $\ce{H2SO4}$, deprotonates to $\ce{HSO4-}$, which can then go to $\ce{SO4^{2-}}$.
Why is that important? Take an ac... |
[![enter image description here][1]][1]
We have to compare the relative basicity in this question.
I know that the more the electron and lone pair density is localised the more will be it’s basicity. So here’s my take on each option.
(**A**)The Nitrogen lone pair undergoes resonance. It’s not good for basi... |
Are there any chemicals that combine readily with oxygen? |
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