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I have read numerous online questions similar to the one I am about to ask. But for most of them the answer has been that the reason one can add water to the unknown concentration solution during a titration is because:
1) Water has a pH of 7
2) This is a volumetric analysis, so as long as one record the volume o... |
How do I interpret a flux quoted in cm⁻² s⁻¹ in atmospheric chemistry? |
I read about entropy from different sources. Still don't get why entropy change has to be greater than zero for a process to go forward. Is it a result of pure observation or is there any theoretical background of this phenomena? |
I suppose that the configurations assigned are opposite as in the left isomer, the left chlorine atom is coming out of the plane of the paper while the other is going into the plane of paper. So it must be trans. Am I going wrong somewhere?![enter image description here][1]
[1]: https://i.stack.imgur.com/XFRin.jpg |
Is the correct configuration assigned to the given pair of geometrical isomers? |
I read about entropy from different sources. Still don't get why (universal) entropy change has to be greater than zero for a process to go forward. Is it a result of pure observation or is there any theoretical background of this phenomena? |
Why is there a difference in the colours of K₂Cr₂O₇ and K₂CrO₄? |
A question in a practice paper I did recently showed the aldol condensation of benzaldehyde with ethanoic acid. I think I am right in saying that carboxylic acids do not form enolates because the carboxyl proton is much more acidic and so this reaction could not take place under basic conditions but it is possible to p... |
Can carboxylic acids be used in the aldol reaction? |
I read about entropy from different sources. Still don't get why (universal) entropy change has to be greater than zero for a process to go forward. Is it a result of pure observation or is there any theoretical background of this phenomena?
I am looking for a simple explanation in classical thermodynamics. |
Excuse me if the cuestion is silly, I have very little knowledge of chemistry.
We can find oxygen in many places in the universe, but all the combustibles we use to ligth fire seems to be organic: carbon, oil, wood, alcohol... so if that is true we could only find fire on Earth, as long as we don´t find organic mate... |
It is possible to find fire outside the Earth? |
Excuse me if the question is silly, I have very little knowledge of chemistry.
We can find oxygen in many places in the universe, but all the combustibles we use to light fire seems to be organic: carbon, oil, wood, alcohol... so if that is true, we could only find fire on Earth, as long as we don´t find organic mater... |
Is it possible to find fire outside the Earth? |
Excuse me if the question is silly, I have very little knowledge of chemistry.
We can find oxygen in many places in the universe, but all the combustibles we use to light fire seems to be organic: carbon, oil, wood, alcohol... so if that is true, we could only find fire on Earth, as long as we don´t find organic mater... |
Is there any way to estimate the alcohol level of a drink with a electric test ? Does alchool in a liquid (wine for ex) is dependent of conductivity more or less ?
Anthony |
How electronically calculate alcoholic level of a liquid? |
What's the byproduct of this reaction? After all, it is a "lysis" reaction. So ... would HCl be a byproduct? |
What is the byproduct from hydrogenolysis of an acyl chloride? |
What's the byproduct of this reaction? After all, it is a "lysis" reaction. So ... would HCl be a byproduct?
|
Zinc Sulfide, Copper Iodide and Copper Bromide all adopt the Zinc Blende structure. My lecture notes suggest that this structure is adopted preferentially over the Wurtzite structure if the bonding is more covalent (why is this?); thus, it's adopted where there is a polarizing cation and a polarizable anion.
Howeve... |
What's the byproduct of this reaction? After all, it is a "lysis" reaction. So ... would HCl be a byproduct?
![enter image description here][1]
[1]: https://i.stack.imgur.com/zf5Wo.jpg |
Is there any way to estimate the alcohol level of a drink with an electric test? Is alcohol in a liquid (e.g wine) dependent on the drink's conductivity?
|
Is there any way to estimate the alcohol content of a drink with an electric test? Is alcohol in a liquid (e.g wine) dependent on the drink's conductivity?
|
Why are the axial bond lengths greater than those of the equatorial bonds in a pentagonal bi-pyramid (PBP) geometry molecule; but the opposite is true for trigonal bi-pyramid (TBP) geometry molecules? I think that it might have something to do with the angles between the bonds, so I intuitively thought of a possible ex... |
Why are the axial bonds in a PBP geometry molecule longer than those in a molecule with TBP geometry? |
I read about entropy from different sources. Still don't get why (universal) entropy change has to be greater than zero for irreversible process. Is it a result of pure observation or is there any theoretical background of this phenomena?
I am looking for a simple explanation in classical thermodynamics. |
> I would like to understand the term stability in organic chemistry.
We can speak of **kinetic** stability or **thermodynamic** stability when we discuss chemical compounds. If a compound is kinetically stable, that indicates that it has a high barrier (large activation energy) to cross and is therefore less react... |
According to Wikipedia, Tin-112 is a stable nuclide, but indium-112 is radioactive (half-life only 14 mins). What is the explanation for this? |
Why is Tin-112 stable, but indium-112 radioactive? |
What is the distance between successive tetrahedral voids in a FCC
Crystal structure?
The distance between a face centered atom and a tetrahedral void is $\sqrt{\frac{3a}{4}}$ if the cube's edge length is $a$. Now If I know the angle made , between the line joining a tetrahedral void and the face centered atom, and t... |
![enter image description here][1]
In this picture, the last two molecules are both rings. However, the second last molecule has a halogen substituent and was named "bromobenzene". The last molecule had a chlorine and a hydroxyl group and was named "4-chlorophenol". Assuming there was no alcohol group, how would w... |
Difference between Phenyl and Benzyl? |
We know that there are silicon analogs of alkanes, but according to Wikipedia, silicon analogs of alkenes or alkynes are virtually unknown. How come? |
How come there aren't any silicon analogs of alkenes or alkynes? |
I suppose that the configurations assigned are opposite as in the left isomer, the left chlorine atom is coming out of the plane of the paper while the other is going into the plane of paper. So it must be trans. Am I going wrong wrong somewhere?![enter image description here][1]
[1]: https://i.stack.imgur.com/Tu4R... |
Is this an error? Why is the nitro group reduced as the benzene ring is oxidized? I don't see any possible reducing agents here..
Also, what is the mechanism of aromatic fluorination by xenon difluoride? This appears analogous to electrophilic aromatic substitution in which benzene acts as a nucleophile and attacks... |
How could we be sure that one certain reaction in equilibrium is dynamic? Since there would be no visible change in vessel, which property of the reaction would provide a proof besides color? Which laboratory technique could be used? |
The reaction as pictured is incorrect, the nitro group is not reduced. As you suggest this is (predominantly) an electrophilic aromatic substitution reaction.
Usually $\ce{HF}$ is used as a catalyst in these reactions and the following equilibrium is established.
$$\ce{XeF2 + HF <=> XeF+ + HF2^-}$$
The elec... |
Zinc sulfide, copper iodide and copper bromide all adopt the zincblende structure. My lecture notes suggest that this structure is adopted preferentially over the wurtzite structure if the bonding is more covalent (why is this?); thus, it’s adopted where there is a polarizing cation and a polarizable anion.
However... |
Why does ionization energy increase as we go from left to right in a period?
In my textbook, the explanation is as follows:
"This is consistent with the idea that electrons added in the same principal quantum level do not completely shield the increasing nuclear charge caused by the added protons. Thus electrons ... |
Why does ionization energy increase as we go from left to right in a period? |
My book says that to favour a reaction by SN1 mechanism we need to use a polar protic solvent and a polar aprotic solvent in a reaction by SN2.
* My Prior Knowledge:*
> There are two types of polar sovents : Polar Protic Solvents contain a hydrogen bonded to a highly electronegative atom. They can solvate both positiv... |
How can I turn Natural gas from liquid to gas? |
I don't if it is a right place to ask this but; Is there any kind of paper or thin material, into what, after freezing it up in refrigerator, if you blow cool air, it will cool it (the air) up and pass it to other side as more cool? |
I keep hearing about this product known as **Triclosan**, and that it is used in sanitizing soap. And I also heard that it is *harmful*, and causes some sort of muscle problems.
> However some people aren't **affected** by it. Why is this, and should I
> be worried about washing my hands? |
Is triclosan harmful? |
I am really confused about how reducing partial pressure of a gas by a certain percentage would impact the behavior of an equilibrium system.
e.g POCl3 (g) <=> POCl (G) + Cl2 (g) is at equilibrium. How would this system behave if the partial pressure of Cl2 is reduced by 75%?
I understand the partial pressure ... |
At 25°C (298 K), the reduction of copper(I) oxide ($ \Delta$H =
58.1 kJ, $ \Delta$S= 165 J/K) is nonspontaneous $ \Delta$G = 8.9 kJ).
Calculate the temperature at which the reaction becomes
spontaneous.
So for this question I'm thinking I use the equation
$$ \Delta G = \Delta H - T\Delta S$$
Then plug in th... |
Calculating the temperature at which a reaction becomes spontaneous? |
I am really confused about how reducing partial pressure of a gas by a certain percentage would impact the behavior of an equilibrium system.
e.g $\ce{POCl3_{(g)} <=> POCl_{(g)} + Cl2_{(g)}}$ is at equilibrium. How would this system behave if the partial pressure of $\ce{Cl2}$ is reduced by 75%?
I understand t... |
$\ce{MgB2}$ is 1 gram-molecule of $\ce{MgB2}$ but 3 gram-atoms of $\ce{MgB2}$.
Why is this so? Let us consider this problem in the familiar mole:
If we were asked how many moles of the substance (molecule) were in this, we would state 1 mole, if there were ${45.3g}$ of substance. However, if we were asked how man... |
Cesium has a larger size and the effective nuclear charge that the valence electron experiences will be far less compared to that of lithium's, right? ...but lithium is still considered the strongest reducing agent among all the alkali metals. Why is this so? |
Why is Lithium the strongest reducing agent, and not Cesium? |
You cannot use values but must determine from looking
The equation I have trouble with is as follows:
>$$\ce{2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2}$$
According to my teacher the entropy is positive. I also got the entropy to be positive, but now that I think of it, the moles is decreasing and one is becoming aqueo... |
![enter image description here][1]
The textbook states that a) has 2 gauche interactions, b) has 3 gauche interactions and c) has 3 interactions
But how do we determine this? I thought a gauche interaction would occur when two methyl groups are side by side, however im unsure where these answers are coming from... |
Determine how many gauche interactions? |
The classic voltaic cell has a Zn anode and Cu cathode. The reduction half reaction occuring at the cathode combines aqueous copper ions and electrons supplied by the anode to form solid Cu. So what is the purpose of the Cu cathode? Cu is produced anyways from the electrons supplied by the anode. Why can't we have inst... |
Why does the cathode have to be made out Cu in a Zn-Cu voltaic cell? |
I don't if it is a right place to ask this but; Is there any kind of paper or thin material, into what, after freezing it up in refrigerator, if you blow cool air, it will cool it (the air) up and pass it to other side as more cool?
EDIT: Is this a clearer version of your question?
Is there a porous thin material... |
The reaction as pictured above is incorrect, the nitro group is not reduced. As you suggest this is (predominantly) an electrophilic aromatic substitution reaction.
Usually $\ce{HF}$ is used as a catalyst in these reactions and the following equilibrium is established.
$$\ce{XeF2 + HF <=> XeF+ + HF2^-}$$
Th... |
PROBLEM:
When I apply paint to my home’s exterior stucco(currently white), the paint changes color. The grays change to purple. The whites change to yellow. Greenish-beige becomes orange. I have purchased many samples of paint, and a color change is apparent for all but the darkest colors. The change in color starts h... |
Paint Changes Color on Stucco. Chemical Reaction is Occurring, but What is Reacting? |
> I would like to understand the term stability in organic chemistry.
We can speak of **kinetic** stability or **thermodynamic** stability when we discuss chemical compounds. If a compound is kinetically stable, that indicates that it has a high barrier (large activation energy) to cross and is therefore less react... |
So, I'm considering an Artsy Fartsy project with hard drive platters. Bring mildly aware of the world around me, I've come to the conclusion that I probably shouldn't grind up modern (or any) electronics and drink it for tea. To that end, is there anything in hard drive platters that is majorly toxic, or are they fine ... |
Do hard drive platters contain toxic chemicals? |
The [Royal Institution of Great Britain][1] has a [Facebook page][2], and I shared this question there, hoping they would respond here. Instead they answered [my inquiry on Facebook][3] itself. Therefore I am quoting it here:
> Hi Martin. I'm afraid David Thompson is a little mistaken. We have multiple examples of F... |
I was just going through my last year's school textbooks and while I was reading this chapter on Redox, this above question crossed my mind.
Shouldn't it be true that since ALL metals lose electrons to get stable, they should also get oxidized. And since they getting oxidized themselves, they should act as reducing ag... |
If losing electrons means getting oxidized, then does it mean that ALL metals are reducing agents, since they themselves get oxidized? |
No, not always.
For example, in the classic Galvanic cell: ![enter image description here][1]
[1]: https://i.stack.imgur.com/W9DBC.gif
In the above image, you have zinc metal acting as a reducing agent at the anode, true to your line of thinking. However, it is also the case that the copper metal at the ca... |
No, not always.
For example, in the classic Galvanic cell: ![enter image description here][1]
[1]: https://i.stack.imgur.com/W9DBC.gif
In the above image, you have zinc metal acting as a reducing agent at the anode, true to your line of thinking. However, it is also the case that the copper metal at the ca... |
I keep hearing about this product known as triclosan, and that it is used in sanitizing soap. And I also heard that it is harmful, and causes some sort of muscle problems.
However some people aren't affected by it. Why is this, and should I
be worried about washing my hands? |
> At $25~^\circ\mathrm{C}$, $298~\mathrm{K}$,, the reduction of copper(I) oxide, $ \Delta H = 58.1~\mathrm{kJ}$, $\Delta S= 165~\mathrm{J/K}$, is nonspontaneous, $ \Delta G = 8.9~\mathrm{kJ}$.
Calculate the temperature at which the reaction becomes spontaneous.
So for this question I'm thinking I use the equation... |
How to calculate the temperature at which a reaction becomes spontaneous? |
A simple explanation would be that the "o on top" denotes standard state and the one without the "o on top" denotes conditions that are not standard state. However, that may not allow you to "get it" so let's look at the equations.
1. $\Delta G^{\circ} = -RT\ln K$
2. $\Delta G = \Delta G^{\circ} + RT \ln K... |
I want to know the difference between $\Delta G$ and $\Delta G$ **"with an o on top"**? I couldn't figure it out.
Ex:
1. $\Delta G^\circ = -RT\ln K$
2. $\Delta G = \Delta G^\circ + RT \ln K$
What is the difference, is it that $\Delta G^\circ$ is the value predicted by the standard free energies and that $\D... |
###Carboxylic acids form enolates
> I think I am right in saying that carboxylic acids do not form enolates because the carboxyl proton is much more acidic and so this reaction could not take place under basic conditions...
They do, if you beat them to it:
1. Dissolve the carboxylic acid in a polar, aprotic so... |
In reading the article abstract [What Oxidation State of Iron Determines the Amethyst Colour?][1], the author states that in regards to the gemstone amethyst, from clear quartz:
> The crystal was transformed into violet amethyst by gamma-irradiation. The change in colour was accompanied by changes in the Mössbauer s... |
How does radiation facilitate the formation of tetravalent iron? |
While I do not think that cocaine is a particularly interesting molecule, the crystal structure has been reported in [Ronald J. Hrynchuk, Richard J. Barton, and Beverley E. Robertson, *Can. J. Chem.*, **1983**, *61*, 481][1]. There is also an open access paper of the XII IUCr Congress available, [R. D. Hrynchuk, R. J. ... |
In reading the article abstract [What Oxidation State of Iron Determines the Amethyst Colour?][1], the author states that in regards to the gemstone amethyst, from clear quartz:
> The crystal was transformed into violet amethyst by gamma-irradiation. The change in colour was accompanied by changes in the Mössbauer s... |
I am studying Syntex's naproxene syntheses and I came across a couple of electrophilic substitutions whose mechanism I can't understand.
The first one is a Friedel-Crafts acylation:
the products are the ones indicated in the picture and they are separated before proceeding. No other byproducts are shown.
![first... |
Some concepts in thermodynamics are unclear due to historic issues.
At first: "In an equilibrium there is a spontaneous direction (the side that is favored) but the reverse reaction also occurs". Thermodinamics arised as a **macroscopic** subjet, in the XIX century two elemental reactions in oposite directions were... |
I am studying Syntex's naproxene syntheses and I came across a couple of electrophilic substitutions whose mechanism I can't understand.
The first one is a Friedel-Crafts acylation:
the products are the ones indicated in the picture and they are separated before proceeding. No other byproducts are shown.
![first... |
I am trying to calculate a cost per hour use of a gas we buy in a cylinder. The details I have been working with are:
[Gas used CP-grade N2 material number: 110628-L can][1]
- Gas: `N`, density = `1.251 g/L @ 0.101 MPa` M (molar mas) = `14.007`
- Gas cylinder: Pressure = `200 bar` or `20 MPa` Cylinder volume `... |
I am trying to calculate a cost per hour use of a gas we buy in a cylinder. The details I have been working with are:
[Gas used CP-grade N2 material number: 110628-L can][1]
- Gas: `N`, density = `1.251 g/L @ 0.101 MPa` M (molar mas) = `14.007`
- Gas cylinder: Pressure = `200 bar` or `20 MPa` Cylinder volume `... |
A double bond/alkene reacts as a nucleophile. I have never seen a reaction where it takes part in an $S_N1$ or $S_N2$ reaction with a halogenoalkane for example. This would presumably be a very useful reaction yet I have never seen it. I assume this is because it doesn't work. Is this the case? If so why? |
How can we say that if a charged nucleophile/base is present we can safely rule out the possibility that the reaction can take place via SN1/E1 mechanism? I have been trying to figure this out since hours. Help would be appreciated. Thank you. [Source][1]
[1]: http://www.masterorganicchemistry.com/2012/11/30/decidi... |
I am trying to calculate a cost per hour use of a gas we buy in a cylinder. The details I have been working with are:
[Gas used CP-grade N2 material number: 110628-L can][1]
- Gas: `N`, density = `1.251 g/L @ 0.101 MPa` M (molar mas) = `14.007`
- Gas cylinder: Pressure = `200 bar` or `20 MPa` Cylinder volume `... |
![question][1]
[1]: https://i.stack.imgur.com/r0L5x.jpg
In this question immediate reaction is to make a grignard reagent with B by reacting it with magnesium and have it attack COX(N(Me)2) to form C
Im not sure how it would be possible to make COX(N(Me)2) from standard reagents.
Are there any obvious ... |
Phosgene chloride (O=CCl2) is a potent toxin and in no way would I consider it a safe or even standard laboratory reagent (at least on an undergraduate level).
Allow me to lead you down the garden path of organic synthesis...
We have a haloalkane. What do we know about such compounds; they have a polarised C-X bo... |
Phosgene (O=CCl2) is a potent toxin and in no way would I consider it a safe or even standard laboratory reagent (at least on an undergraduate level).
Allow me to lead you down the garden path of organic synthesis...
We have a haloalkane. What do we know about such compounds; they have a polarised C-X bond (x=hal... |
I’m not sure if I’m missing your question, but I thought that perhaps you could use the relation $\mathrm{pH}=\mathrm{p}K_\text{a}$ at the half equivalence point? The answer would be still incorrect but closer?
Otherwise, you could probably use stoichiometry to solve for $K_\text{a}$ at the beginning or the end of t... |
I'm reading a review article on photocatalytic water splitting (using semiconductors) and I came across the following:
"To achieve photocatalytic water splitting using a single photocatalyst, the bandgap of the semiconductor must straddle the reduction and oxidation potentials of water, which are +0 and +1.23 V vs t... |
Why We find big spaces left in the periods of the Periodic Table
between H and He; Be and B, or Mg and Al?
What is the logic of such organization of
the periods? |
Why We find big spaces left in the periods of the Periodic Table between $\ce{H}$ and $\ce{He}$; $\ce{Be}$ and $\ce{B}$, or $\ce{Mg}$ and $\ce{Al}$?
What is the logic of such organization of the periods? |
Why do we find big spaces in the periods of the Periodic Table between $\ce{H}$ and $\ce{He}$, $\ce{Be}$ and $\ce{B}$, and $\ce{Mg}$ and $\ce{Al}$?
What is the logic of such organization of the periods? |
Solomons and Fryhle has an example in which they have showed a very simple substitution reaction. The question was to synthesize methyl iodide. What they have done is taken methyl chloride and produced methyl iodide in the presence of NaI and ethanol through an SN2 mechanism. My question is -why did they use ethanol? I... |
Why do we use ethanol in SN2 reaction? |
> No other byproducts are shown
I haven't checked the original Syntex patent (if you've ever written a patent you know that sometimes important details are omitted), but it seems odd to me that those two isomers are claimed to be the most significant isomers formed. As you point out, the 2-methoxy-5-acetoxy isomer i... |
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