instruction stringlengths 15 21.8k |
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Why does this luminesce? |
Not long ago, I performed a reaction between siloxene and cerium(IV) sulphate. When the two were mixed, the mixture produced an orange-yellow glow. WHy did these glow, though? What is it about the two chemicals in particular that makes this happen?
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## Method for synthesising siloxene:
> Carefully measure out... |
Not long ago, I did an experiment where siloxene and cerium(IV) sulphate were mixed together. The mixture produced an orange-yellow glow. Why does it glow? What is it about the two chemicals in particular that makes this happen?
---
## Method for synthesising siloxene:
> Carefully measure out 50 cm<sup>3</sup> o... |
Why does a mixture of siloxene and cerium(IV) sulfate luminesce? |
Despite very similar skeletal structures, the difference in acid strength is quite significant. **What is the reason for that**?
It seems that the inductive effect plays a role, but **how can we explain the inductive effect in ethanedioic acid** as there is same group on opposite sides?
**How does the inductive... |
Some intra-molecular bonds are rotatable in the sense that the torsion angle around this bond is flexible (for example, Psi and Phi angles of a protein backbone). Others are essentially fixed (for example, the Omega angle in the peptide bond of a protein backbone). Is there an operational definition, or a published stu... |
Is there a definition of rotatable bond? |
Some intramolecular bonds are rotatable in the sense that the torsion angle around this bond is flexible (for example, $\psi$ and $\phi$ angles in a protein backbone). Others are essentially fixed (for example, the $\omega$ angle in the peptide bond in a protein backbone).
Is there an operational definition, or a p... |
Despite very similar skeletal structures, the difference in acid strength is quite significant. What is the reason for that?
It seems that the inductive effect plays a role, but what is the explanation for the inductive effect in oxalic acid as there is same group on opposite sides?
How does the inductive effect ... |
I am looking to produce hydrogen gas in a small amount with supplies I currently have. Most of the methods I have seen involve reacting zinc or magnesium with $\ce{HCl}$ to obtain the gas, but I do not have zinc or magnesium at the moment.
Is there any reason why aluminum cannot be used just as effectively as zinc? ... |
Can aluminum and hydrochloric acid be used to generate hydrogen gas? |
I have a buffer containing 0.2 M of the acid $\ce{HA}$, and 0.15 M of its conjugate base $\ce{A-}$, with a pH of 3.35. I need to find the pH after 0.0015 mol of $\ce{NaOH}$ is added to 0.5 L of the solution.
I started by converting everything to moles, writing out an equation for $\ce{HA}$ and $\ce{OH-}$ reacting to... |
Several sources ([1][1], [2][2]) suggest that charging Li-ion batteries in low-temperature conditions result in lithium plating. This seems pretty logical since low temperature reduces ion mobility, and provided there exists a high enough charge current, lithium ions don't have time to intercalate into carbon layers of... |
Why is lithium plating irreversible in Li-ion cells? |
- [discover][1]
- [invent][2]
- [create][3]
- [innovate][4]
Create is totally weird with chemistry, you can create item, but substance?
Innovate is more about improving something existing.
This leaves us with discover and invent, which in case of chemistry seems to me almost equivalent. For "invent" I w... |
So we have to select the set of elements which will have almost the same atomic radii:
1. O, S, Se, Te
2. Li, Be, B, C
3. Fe, Co, Ni, Cu
4. Li, Be, B, C
Now I googled the atomic radii of the third set and found them to be extremely close to one another: all of them are nearly 135 pm (according to empiric... |
$$\ce{NH_3 + HCl -> NH_4Cl}$$
The electronic structure of ammonia is such so that the nitrogen atom has an outer shell with a lone pair of electrons.
When ammonia reacts with hydrochloric acid (above), the hydrogen from the $\ce{HCl}$ moves to the ammonia. However, it leaves its electrons behind because there is ... |
It's very difficult to get accurate information concerning household bleach residues. Imagine, for instance, that you pour pure (or diluted) bleach onto fabric or synthetic foam and let it dry without rinsing (as a scientific experiment). [Some sources][1] say: it will totally "vanish" (with air and/or light), leaving ... |
Does bleach (without rinsing) leave residue(s) and can vinegar, baking soda, or vitamin C neutralize it/them? |
I have noticed that, when exposed to water for a few days, the steel in my wagon turns into rust. After several more weeks, the rust that formed is dissolved in the water, and once I pour the water out there isn't any rust where there previously was rust.
This is unusual because iron oxides and iron hydroxides (the ... |
If place a can of pressurized liquid butane (such as a lighter refill canister) into a freezer to get it below its boiling point of $-1\ \mathrm{^\circ C}$,
and then release it into a container kept at a freezing temperature, will it remain in the liquid state without boiling off (until it reaches its boiling point), ... |
How can I measure the resistance of a gel electrolyte using a multimeter? I know the formula to measure the conductivity of a gel electrolyte is k = (1/R) * (d/a)
where k is the conductivity (S/cm), R is the resistance (of the electrolyte), d is the distance between the two electrodes, and a is the effective area of... |
Is there proof or a theory that shows that the first amino acid syntheses on Earth were influenced by a change in heat, gravity, radiation, or something similar? |
How did the first amino acids appear on Earth? |
Peptide bonds are synthesized when the carboxyl group of one amino acid molecule reacts with the amino group of the other amino acid molecule, causing the release of a molecule of water.
Water molecules consist of a **hydroxyl from a carboxyl group** and a **hydrogen from an amino group**.
And that seems a bit st... |
Do carboxyl groups behave like bases and amino groups behave like acids when peptide bonds are created? |
So we have to select the set of elements which will have almost the same atomic radii:
1. O, S, Se, Te
2. Li, Be, B, C
3. Fe, Co, Ni, Cu
Now I googled the atomic radii of the third set and found them to be extremely close to one another: all of them are nearly 135 pm (according to empirical data). Is there ... |
Some intramolecular bonds are rotatable in the sense that the torsion angle around this bond is flexible (for example, $\psi$ and $\phi$ angles in a protein backbone). Others are essentially fixed (for example, the $\omega$ angle in the peptide bond in a protein backbone).
Is there an operational definition, or a p... |
The wikipedia [article][1] on trinitromethane claims that:
>There is some evidence that the anion (which obeys the 4n+2 Hückel rule) is aromatic.
Unfortunately the citation is behind a paywall so I can't read it but my first obvious question is how can the trinitromethane anion obey Hückel's rule? Two of the requir... |
What are hybridisation states of each carbon atom in the following compounds?
$\ce{CH2=C=O}$
$\ce{CH3CH=CH2}$
$\ce{(CH3)2CO}$
$\ce{CH2=CHCN}$
$\ce{C6H6}$ |
Yesterday, my girlfriend remarked on how pleased she was with the effects of the hair moisturizer she has been using: "I started using it just a month ago, and look, it's healed all the damage." I complimented her, then said "...but hair is dead, so it couldn't have helped heal it." She replied, "Well it fills in the c... |
Do any substances work like consumers of hair moisturizer believe it to work? |
> Is there an operational definition, or a published study where a
> general definition is given, which would allow me to recognize in a
> generic molecule (or at least an organic molecule) whether a given
> bond is rotatable or not?
It depends on your purpose. Why do you want to identify some bonds and call the ... |
Electrical properties of very simple systems can be calculated using [NEGF][1]. Is there a way to calculate the resistance (and other electrical properties) of a conjugated polymer, as a function of degree of polymerization (DP)?
[1]: http://www.physics.udel.edu/~bnikolic/QTTG/shared/reviews/nanoscale_device_mod... |
Resistance of conjugated polymers as a function of degree of polymerization (DP)? |
> Is there an operational definition, or a published study where a
> general definition is given, which would allow me to recognize in a
> generic molecule (or at least an organic molecule) whether a given
> bond is rotatable or not?
It depends on your purpose. Why do you want to identify some bonds and call the ... |
I am attempting to use sodium polyacrylate as a sodium transport mechanism in a sulfur-bromine cell. I can upset the sodium balance with sodium salts, but the contamination introduced by the non-metallic ion from that salt is unacceptable. Water is a solvent that can be ultimately coerced into a solution compatible wit... |
What are the non-aqueous solvents for sodium polyacrylate? |
How long would it take to dissolve a human body using Fluoroantimonic Acid?
I understand that since the human body isn't homogenous, it's a bit tough to get the exact calculation, but lets say we create a mannequin using the material in the human body that Fluoroantimonic acid takes the longest time to dissolve - ho... |
How long would it take to dissolve someone using Fluoroantimonic Acid? |
How does oil on the surface of water prevent rust? |
Despite very similar skeletal structures, the difference in acid strength between oxalic acid (ethanedioic acid) and malonic acid (propanedioic acid) is quite significant. What is the reason for that?
It seems that the inductive effect plays a role, but what is the explanation for the inductive effect in oxalic acid... |
Can you predict the resistance of conjugated polymers as a function of degree of polymerization (DP)? |
After writing [an answer][1] on worldbuilding.SE, I came here to ask a question. How long would it take to dissolve a human body using fluoroantimonic acid?
I understand that since the human body isn't homogenous, it's a bit tough to get the exact calculation, but lets say we create a mannequin using the material in... |
How long would it take to dissolve someone using fluoroantimonic acid? |
For example, polyacetylene is a [conjugated system][1], i.e. with de-localized p-orbitals, but accroding to [Chiang et. al. (1977)][2] polyacetylene is semiconducting, and becomes conductive only when doped with Cl/Br/I/AsF<sub>5</sub>.
Isn't the conjugation alone enough to allow conductivity?
[![Electrical condu... |
Does the delocalization on p-orbitals ensure conductivity? |
Does the delocalization of p-orbitals ensure conductivity? |
For example, polyacetylene is a [conjugated system][1], i.e. with de-localized p-orbitals, but accroding to [Chiang et. al. (1977)][2] polyacetylene is semiconducting, and becomes conductive only when doped with Cl/Br/I/AsF<sub>5</sub>. One reason they mention is:
Isn't the conjugation alone enough to allow conducti... |
Beryllium Hydride Doesnt Match the Octet Rule! Isn't this impossible? Unless there are more elements involved? |
Beryllium hydride doesn’t match the Octet Rule! Isn't this impossible? Unless there are more elements involved? |
Beryllium hydride does not obey the octet rule. Isn't this impossible, unless there are more elements comprising the molecule? |
For example, polyacetylene is a [conjugated system][1], i.e. with de-localized p-orbitals, but accroding to [Chiang et. al. (1977)][2] polyacetylene is semiconducting, and becomes conductive only when doped with Cl/Br/I/AsF<sub>5</sub>.
Isn't the conjugation alone enough to allow conductivity?
[![Electrical condu... |
When you put Mg into water a few H2 bubbles appear. But when you put Mg into a NaCl solution there is a vigorous release of H2, why is this and what reactions are taking place?
Ray |
There is a question on my assignment about stoichiometry.I spent 2 whole days searching and review this topic but still clueless.Please help me
Reaction in lithium ion battery
Li(s) + CoO2(s) → LiCoO2(s)
When the battery is recharged, electrical energy will reverse the reaction. How do the relatives amounts of li... |
Does relative amount of lithium and cobalt oxide change in recharged battery? |
When you put $\ce{Mg}$ into water a few $\ce{H2}$ bubbles appear. But when you put $\ce{Mg}$ into a $\ce{NaCl}$ solution there is a vigorous release of $\ce{H2}$, why is this and what reactions are taking place? |
Why does Mg react vigorously in NaCl solution and less so in water? |
There is a question on my assignment about stoichiometry. I spent 2 whole days searching and review this topic but still clueless.
Reaction in lithium ion battery
$$
\ce{Li(s) + CoO2(s) → LiCoO2(s)} \, .
$$
When the battery is recharged, electrical energy will reverse the reaction. How do the relatives amounts o... |
I distinctly remember a side-by-side comparison from a book where there are two nails submerged in water, in two beakers: one nail had a layer of oil on top of the water, and that nail didn't rust; the other did.
It seems that oiling iron/steel products is supposed to prevent them from rusting:
http://www.justans... |
I distinctly remember a side-by-side comparison from a book where there are two nails submerged in water, in two beakers: one nail had a layer of oil on top of the water, and that nail didn't rust; the other did.
It seems that oiling iron/steel products is supposed to prevent them from rusting:
http://www.justans... |
I completed an electrolysis experiment. I used copper electrodes and a copper sulphate solution, and my independant variable was the temperature of the electrolyte. I was just wondering if increasing the temperature has a positive correlation? |
About maximum 20% (as i remember, perhaps more now) of the Li goes (as Li+) out of the structure of $LiCoO_2$, through the elctrolyte, and into the electrode on the other side of the battery. That electrode consist mainly of graphite, which intercalates the Li in its layers in a quasi-metallic form.
So it is $Li_{1-... |
In the Hoesch reaction, an alkyl cyanide reacts with a polyhydric benzene ring, and forms an imine salt by attacking the activated benzene ring. Most acid derivatives (and even alkyl cyanide itself with phenol) results in attack at the alcohol's oxygen, which is more nucleophilic than the benzene ring. In this case how... |
Why does RCN attack the benzene ring in Hoesch Reaction? |
[![enter image description here][1]][1]
In the first example, if you add up the number of carbon which has a substituent, you will get 2+4+4 = 10. However, if you start from left to right, then you'd get 2+2+4=8. Why don't we follow the latter one when it gives us a lower number? (Lowest set of locant rule.)
The ... |
Delocalized $\pi$ orbitals **do** allow for mobile charges. The catch there is "allow." Just because these systems *can* have mobile charges does not make them *conductive*.
Conductivity can be defined as:
$\sigma = n e \mu$
where $e$ is the charge on an electron, $\mu$ is the charge mobility, and $n$ is the numbe... |
About maximum $20~\%$ (as I remember, perhaps more now) of the $\ce{Li}$ goes (as $\ce{Li+}$) out of the structure of $\ce{LiCoO2}$, through the elctrolyte, and into the electrode on the other side of the battery. That electrode consists mainly of graphite, which intercalates the $\ce{Li}$ in it's layers in a quasi-met... |
Delocalized $\pi$ orbitals **do** allow for mobile charges. The catch there is "allow." Just because these systems *can* have mobile charges does not make them *conductive*.
Conductivity can be defined as:
$\sigma = n e \mu$
where $e$ is the charge on an electron, $\mu$ is the charge mobility, and $n$ is the numbe... |
I'm comparing a model with chemistry at equilibrium versus a kinetic chemistry.
I take a network of two reactions: methane steam reforming (MSR) and water gas shift (WGS) at 700°C.
I calculated extent of reaction of both reaction, with the equilibrium hypothesis, solving a system of two non-linear equation cont... |
Since I calculate NMR spectra for a while by simply using one of recommendations by [CHEmical SHIft REpository][1]:
mPW1PW91/6-311+G(2d,p)-SCRF//B3LYP/6-31+G(d,p)
without thinking to much how it actually works*, there is a common misprediction that I'd like to understand.
It seems to be that the shift/shie... |
Would 44.5 mg/L be a measurement of weight or volume? |
Is 44.5 mg/L a measurement of weight or volume? |
Today, my chemistry teacher gave the organic conversion as homework.
benzene to 3 bromoiodobenzene
I tried something like,
![enter image description here][1]
[1]: https://i.stack.imgur.com/6pf70.jpg
I am not sure about it, can someone review my conversion(as I have got exam tomorrow)?
|
Today, my chemistry teacher gave the organic conversion as homework.
Benzene to 3-bromoiodobenzene
I tried something like:
![enter image description here][1]
[1]: https://i.stack.imgur.com/6pf70.jpg
I am not sure about it, can someone review my conversion (as I have got an exam tomorrow)?
|
The internet is full of videos like [this][1] showing water bottles for drinking used to supercool water. These bottles, not unexpectedly, appear a bit finicky, since they have lots of edges to serve as nucleation sites for ice crystals. What container would work best for this sort of demonstration?
Is the most impo... |
The internet is full of videos like [this][1] showing water bottles for drinking used to supercool water. These bottles, not unexpectedly, appear a bit finicky, since they have lots of edges to serve as nucleation sites for ice crystals. What container would work best for this sort of demonstration?
Is the most impo... |
Indeed, the first compound in your sketch is numbered incorrectly according to IUPAC. [IUPAC rules for branched hydrocarbons][1] say: "When series of locants containing the same number of terms are compared term by term, that series is "lowest" which contains the lowest number on the occasion of the first difference. T... |
I'm looking for a reasonably accurate density of a mixture of two gases that act quite unlike ideal gases (generally steam and water-miscible solvents). We can get a first order estimate by taking a molar average but that can be an order of magnitude off, as in the case of water/ammonia.
Literature is the obvious p... |
In the [Hoesch reaction][1], an alkyl cyanide reacts with a polyhydric benzene ring, and forms an imine salt by attacking the activated benzene ring. Most acid derivatives (and even alkyl cyanide itself with phenol) results in attack at the alcohol's oxygen, which is more nucleophilic than the benzene ring. In this cas... |
You need to incorporate all $3N-5$ modes (both bends and both stretches) in order to accurately calculate the ZPE even if, per Jan's answer, you can neglect one of the bending modes in constructing an accurate model of the PES. Even though the bends appear identical in mind's eye, both of their (degenerate) ZPE's must ... |
You need to incorporate all $3N-5$ modes (both bends and both stretches) in order to accurately calculate the ZPE even if, per Jan's answer, you can neglect one of the bending modes in constructing an accurate model of the PES. Even though the bends appear identical in mind's eye, both of their (degenerate) ZPE's must ... |
If the transfer of 1kj of energy to a quantity of water causes its temperature to rise 10degrees C, what is the mass of the water? ok so I know how to do the math and everything but im so confused with significant figures. so if 1 Kj or 100 J only has 1 sig fig than would i write 23.90 as 20? |
If the transfer of $1~\mathrm{kJ}$ of energy to a quantity of water causes its temperature to rise $10~^\circ\mathrm{C}$, what is the mass of the water? I know how to do the math and everything but I'm so confused with significant figures. If $1~\mathrm{kJ}$ or $100~\mathrm{J}$ only has 1 significant figure, than woul... |
How to recognise the significant figures in given input values for the calculated output value? |
According to the article [Extending the Shelf Life of Fresh Sliced Mushrooms][1], it states that 5% (v/v) hydrogen peroxide is an effective means for the preservation of sliced mushrooms.
In regards to the preservation:
> In the USA hydrogen peroxide
is an approved bactericide for some dairy products and is used... |
According to the article [Extending the Shelf Life of Fresh Sliced Mushrooms][1], it states that 5% (v/v) hydrogen peroxide is an effective means for the preservation of sliced mushrooms.
In regards to the preservation:
> In the USA hydrogen peroxide
is an approved bactericide for some dairy products and is used... |
[![enter image description here][1]][1]
In the first example, if you add up the number of carbon which has a substituent, you will get 2+4+4 = 10. However, if you start from left to right, then you'd get 2+2+4=8. Why don't we follow the latter one when it gives us a lower number? (Lowest set of locant rule.)
The ... |
I want to prepare a sample of Lithium Metaborate (LiBO2)and need to dissolve it for this purpose. The only solvents I found so far are water and ethanol, wheras in ethanol one cannot dissolve enough. Water is quite nice from the concentration point of view but its high surface tension and tendency of wetting forbids (m... |
I want to prepare a sample of Lithium Metaborate ($\ce{LiBO2}$) and need to dissolve it for this purpose. The only solvents I found so far are water and ethanol, whereas in ethanol one cannot dissolve enough. Water is quite nice from the concentration point of view but its high surface tension and tendency of wetting f... |
Alternative to water as solvent for Lithium metaborate? |
Seems so simple but is confusing me as when I take into account final weight I don't get one of the answers.
An iron ore was analysed by dissolving a $1.1324~\mathrm{g}$ sample in concentrated $\ce{HCl}$ and converting it to give $0.5394~\mathrm{g}$ of pure $\ce{Fe2O3}$. The $\mathrm{m\%}_\ce{Fe}$ in the sample is e... |
I want to prepare a sample of lithium metaborate ($\ce{LiBO2}$) and need to dissolve it for this purpose.
The only solvents I found so far are water and ethanol. In ethanol, one cannot dissolve enough of the solute. Water is quite nice from the solubility point of view, but its high surface tension and tendency of w... |
Alternative to water as solvent for lithium metaborate? |
Seems so simple but is confusing me as when I take into account final weight I don't get one of the answers.
An iron ore was analysed by dissolving a $1.1324~\mathrm{g}$ sample in concentrated $\ce{HCl}$ and converting it to give $0.5394~\mathrm{g}$ of pure $\ce{Fe2O3}$. The $\mathrm{m\%}_\ce{Fe}$ in the sample is e... |
If the transfer of $1~\mathrm{kJ}$ of energy to a quantity of water causes its temperature to rise $10~^\circ\mathrm{C}$, what is the mass of the water? I know how to do the math and everything but I'm so confused with significant figures. If $1~\mathrm{kJ}$ or $100~\mathrm{J}$ only has 1 significant figure, than woul... |
I would like to know what precautions should be taken when handling liquids like trichloroethylene, tetrachloroethylene, dichlormethane, and mercury. Of these, which is most toxic?
I have seen people handle mercury in rooms without fume hoods. I don't have access to a fume hood, so is it adequate protection if I we... |
What is the branch of chemistry that deals with skin adhesives? Is there an adhesive that is not water soluble that is safe to use every day? |
My 10th grade chemistry book states that:<br>
"Metals react with water and produce a metal oxide and hydrogen gas. Metal oxides that are soluble in water dissolve in it to further form metal hydroxide.
Metals like potassium and SODIUM react violently with cold water. In case of sodium and potassium, the reaction is s... |
Does sodium produce water when it reacts with water? |
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