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I refer you to the second link in my answer for [How does one recognized Td/Oh symmetry in molecules?](http://chemistry.stackexchange.com/a/327/84), which (according to the abstract) describes some high symmetry species of unusual point groups $T$, $O$ and $I$. Additionally, the molecule [\[6.6\]chiralane][1] has $T$ s... |
Burning metals like sodium should not be extinguished with standard fire extinguishers, but they require either sand or a special class D fire extinguisher.
Now, if there is a fire in the lab and the closest fire extinguisher is one of those class D extinguishers meant for metal fires, can those be used for other t... |
Can class D fire extinguishers be used for other fire types than metal fires? |
In studies like this: http://www.fda.gov/food/foodsafety/foodcontaminantsadulteration/chemicalcontaminants/acrylamide/ucm053549.htm
how do they determine the concentration of acrylamide from solid foods? |
How do you determine the amount of acrylamide in foods such as baked fries? |
I cannot find much guidance in the literature. Any ideas as to what the mechanism of this reaction might be?
I'm a new user so I can't post an image yet, but here's a link:
http://malaria.ourexperiment.org/data/files/2141.png |
I cannot find much guidance in the literature. Any ideas as to what the mechanism of this reaction might be?
![http://malaria.ourexperiment.org/data/files/2141.png][1]
[1]: https://i.stack.imgur.com/WX7Mw.png |
There are many food studies which determine the concentration of a substance in a food item.
For example, [this study][1] determines the concentration of acrylamide in solid foods like fries.
By what experimental technique is this done?
[1]: http://www.fda.gov/food/foodsafety/foodcontaminantsadulteration/c... |
I'm wondering why a lot of drugs are in this hydrochloride form.
+ Cetirizine Hydrochloride
+ Methylphenidate hydrochloride
+ Tramadol hydrochloride
+ etc.
I'm really curious to know why this form is so common for the presentation of a drug ? |
Why so many drugs are in the hydrochloride form? |
Why are many drugs in the hydrochloride form? |
I tried to fractionate the protein as a function of their size with a ultrafiltration membrane. I observed a higher concentration of chloride in my permeate than in my feed or retentate. The protein do not pass through the membrane and the filtration has been done at pH=7. A was asking how is a possible to have a highe... |
I tried to fractionate proteins as a function of their size with an ultrafiltration membrane. I observed a higher concentration of chloride in my permeate than in my feed or retentate. The proteins do not pass through the membrane and the filtration has been done at pH=7. I asked, how is it possible to have a higher co... |
I tried to fractionate proteins as a function of their size with an ultrafiltration membrane. I observed a higher concentration of chloride in my permeate than in my feed or retentate. The proteins do not pass through the membrane and the filtration has been done at pH = 7. I asked, how is it possible to have a higher ... |
Adding solid copper, 5% vinegar, and hydrogen peroxide (H2O2) together causes copper acetate to form. The process will occur very slowly without hydrogen peroxide. Adding H2O2 speeds the formation of copper acetate. How can I test the solution to see if all of the acetic acid has been converted into copper acetate? Ple... |
How to optimize copper acetate formation? |
Mixing solid copper, 5% vinegar, and hydrogen peroxide ($\ce{H2O2}$) causes copper acetate to form. The process will occur very slowly without hydrogen peroxide. Adding $\ce{H2O2}$ speeds the formation of copper acetate.
How can I test the solution to see if all of the acetic acid has been converted into copper ac... |
How can one optimise the formation of copper acetate? |
Mixing solid copper, 5% vinegar, and hydrogen peroxide ($\ce{H2O2}$) causes copper acetate to form. The process will occur very slowly without hydrogen peroxide. Adding $\ce{H2O2}$ speeds the formation of copper acetate.
How can I test the solution to see if all of the acetic acid has been converted into copper acet... |
How can one optimize the formation of copper acetate? |
How can one optimise the formation of copper acetate? |
<p>
Chemistry - Stack Exchange is for <span class="revision-comment">scientists, academics, teachers and students of <b>chemistry</b></span>.
</p>
<p>Question may be of any level, but should be of the following types:</p>
- Questions asking for explanation of a chemistry concept
- Questions relating to obser... |
$\ce {CO2}$ capture and recycling (CCR) has been suggested as one form of round-trip electricity storage, with a round trip being:
- electricity
- -> something that can hang around for hours to months
- -> electricity some time later
The proposal goes something like this: capture the $\ce {CO2}$ produced f... |
Energ-efficiency aside, what are the chemical constraints on CO2 capture and methanation? |
$\ce {CO2}$ capture and recycling (CCR) has been suggested as one form of round-trip electricity storage, with a round trip being:
- electricity
- $\to$ something that can hang around for hours to months
- $\to$ electricity some time later
The proposal goes something like this: capture the $\ce {CO2}$ prod... |
Energy-efficiency aside, what are the chemical constraints on CO2 capture and methanation? |
I was reading up on a wonderful little chemical compound known as chlorine trifluoride (ClF<sub>3</sub>). For a primer, check out Dr. Derek Lowe's blog post here: [Sand Won't Save You This Time][1]. The title of the post is quite telling; this compound is so reactive with other compounds - any other compound, really - ... |
Flammability (NFPA) - how is it defined? |
I was reading up on a wonderful little chemical compound known as chlorine trifluoride (ClF<sub>3</sub>). For a primer, check out Dr. Derek Lowe's blog post here: [Sand Won't Save You This Time][1]. The title of the post is quite telling; this compound is so reactive with other compounds - any other compound, really - ... |
How does Polytetrafluoroethylene (Teflon) differ from Polyvinylidene fluoride (PVDF) as a membrane material? |
How does Polytetrafluoroethylene (Teflon) differ from Polyvinylidene fluoride (PVDF) as a protein binding membrane material? |
You have found one of biggest flaws in the [NFPA "Fire Diamond"](http://en.wikipedia.org/wiki/NFPA_704). The NFPA rates the flammability of the compound **as a fuel**. ClF<sub>3</sub> is not a fuel. It is an oxidant. ClF<sub>3</sub> is playing the role that oxygen normally does. It causes fuels (reductants) to burn by... |
I have adapted the lab experiment described in this [_J. Chem. Ed._ article](http://pubs.acs.org/doi/abs/10.1021/ed101195v) for the organic chemistry lab course I teach. In the past year, the first year of implementation, I have had 67 failures (100% failure rate) on the extraction part of this experiment.
The exper... |
I have adapted the lab experiment described in this [_J. Chem. Ed._ article](http://pubs.acs.org/doi/abs/10.1021/ed101195v) for the organic chemistry lab course I teach. In the past year, the first year of implementation, I have had 67 failures (100% failure rate) on the extraction part of this experiment.
The exper... |
I am in high school, I would like to potentially an experiment on this for a project. I've done quite a bit of research into the different methods I could use (see 2.4.2 here: http://www.acgpubs.org/RNP/2011/Volume%205/Issue%201/17_RNP-1008-300.pdf) but I still cannot find much information that I could use to formulate... |
How does temperature affect the concentration of flavonoids in orange juice? |
I am in high school, and I would like to do an experiment on this for a project.
I've done quite a bit of research into the different methods I could use (see 2.4.2 [here][1]) but I still cannot find enough information to formulate a hypothesis. It would be useful iff you could point me in the right direction. So... |
I am looking into implementation of Ewald summation techniques for a number of point charges in periodic 3D space (i.e. a molecular simulation box with periodic boundary conditions). The “mainstream” Ewald-type techniques I know are:
- original Ewald scheme
- particle-mesh Ewald (PME)
- smooth particle-mesh Ewald ... |
I'm working with some very basic free-radical initiated polymerization reactions. For the most part, I just follow a recipe I'm given (by a member of my group or the broader literature), it works, and I don't worry too much about the chemistry of why it works. Clearly, that will only work for so long, and I'd like to b... |
Are there any general chemical rules for choosing initiators for a polymerization reaction? |
$\ce {CO2}$ capture and recycling (CCR) has been suggested as one form of round-trip electricity storage, with a round trip being:
- electricity
- $\to$ something that can hang around for hours to months
- $\to$ electricity some time later
The proposal goes something like this: capture the $\ce {CO2}$ prod... |
I understand that covalent bonding is an equillibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other? Also, am I right to thing that repulsion occuring when atoms are too close together comes from electrostatic interaction? |
I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
Also, am I right to think that "repulsion occurs when atoms are too close together" comes from electrostatic interaction? |
When looking at excited states of molecules, $\delta$ bonds are relatively common, but I've never come across a molecule with a $\delta$ bond in its ground state.
Are there molecules with $\delta$ bonds in their ground states?
What about even higher angular momentum states ($\phi$ and $\gamma$ bonds)? |
Are there any molecules with delta bonds in their ground states? |
How does brewing time and brewing temperature affect the flavonoid concentration of green tea? |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
> I understand that covalent bonding is an equilibrium state between attractive and repulsive forces, but which one of fundamental forces actually causes atoms to attract each other?
**The role of Pauli Exclusion in bonding**
It is an unfortunate accident of history that because chemistry has a very convenient an... |
PTFE and PVDF (durapore) are both used in protein binding filter membranes. Chemically speaking the two polymers differ quite significantly due to the additional fluorides and molecular weight. Their protein-binding properties also differ. I'm curious about how the chemical differences affect their properties as a memb... |
PTFE and PVDF (durapore) are both used in protein binding filter membranes (Millipore specifically). Chemically speaking the two polymers differ quite significantly due to the additional fluorides and molecular weight. Their protein-binding properties also differ. I'm curious about how the chemical differences affect t... |
Well, I would name it [tetrahydrofuran](http://en.wikipedia.org/wiki/Tetrahydrofuran), aka THF, but of course that's only because I already know the molecule. It's a very common organic solvent.
If you didn't know its common name, you could try to name it according to IUPAC nomenclature. It's a [ester][1], and it's ... |
What are some qualitative guidelines one should know regarding the temperature dependencies (of tha gas and maybe the radiation, if that makes sense) for and absorption spectroscopy measurement.
How does for example a rise in temperature influence the absorption lines? |
Well, the molecule you draw is [**tetrahydrofuran**](http://en.wikipedia.org/wiki/Tetrahydrofuran), aka THF, but of course the only way you can guess that is if you already know the molecule. It's a very common organic solvent.
If you didn't know its common name, you could try to name it according to IUPAC nomenclat... |
What are some qualitative guidelines one should know regarding the temperature dependencies (of the gas and maybe the radiation, if that makes sense) for an absorption spectroscopy measurement?
How does, for example, a rise in temperature influence the absorption lines? |
I picked up a metal fence loop cap today and took it home just because I liked the shape.
![fence loopcap][1]
(^ not mine)
I cleaned it, but some of the paint is chipping off. I'm only vaguely thinking about lead, and I'm not going to chew on it, so I don't want to buy a test kit. Is there a way I could test for ... |
Can I test for lead with household chemicals? |
If you're testing for whether it's entirely made of lead, you can do it with a simple density calculation rather than anything chemical - an easy typical way to do this is to immerse it in a known volume of water and see how much volume the object adds, then divide the weight by that. Lead is the one of the heaviest co... |
I know ***phenols are more acidic as compared to alcohols***, but are they considered different from alcohol?
Sure you can study something as a subset, but are **phenols** considered a subset of alcohols or are they considered as completely different from alcohol. My confusion is due to the fact that both of them c... |
1. Meh, personally I'm not worried about the vapours. You'll be sane and be doing this in an at least somewhat ventilated space, right? Don't do anything outright stupid, but also don't fear the substances so much that your defences cause you to trip and break a toe. HCl and NaOH aren't exactly harmless, but they're no... |
I'm working with some very basic free-radical initiated polymerization reactions. For the most part, I just follow a recipe I'm given (by a member of my group or the broader literature), it works, and I don't worry too much about the chemistry of why it works. Clearly, that will only work for so long, and I'd like to b... |
General remark: get a bit of lead (metal or salt - whatever you look for) to have a positive control for your experiments.
More non-chemical tests for lead (metal):
- lead is soft: you can cut/scrape it quite easily with a normal knife.
- sheats of lead are easily bent, and they stay so.
- For bigger pie... |
Is $CCl_4$ an electrolyte all by itself or does it needs something to be added to it so that it becomes an electrolyte ?
Also is it *weak* or *strong* ? |
Is $CCl_4$ an electrolyte? |
If you're testing for whether it's entirely made of lead, you can do it with a simple density calculation rather than anything chemical - an easy typical way to do this is to immerse it in a known volume of water and see how much volume the object adds, then divide the weight by that. Lead is the one of the heaviest co... |
Is CCl4 an electrolyte? |
Someone gave me definition as follows:
> The number of electron or proton present in a **neutral atom** is called atomic number. It is represented by `Z`.
What does neutral mean here. Why doesn't he just said "..present in an atom is called..."? |
What is a neutral atom? |
Someone gave me definition of atomic number as follows:
> The number of electron or proton present in a **neutral atom** is called atomic number. It is represented by `Z`.
What does neutral mean here. Why doesn't he just said "..present in an atom is called..."? |
Someone gave me definition of atomic number as follows:
> The number of electron or proton present in a **neutral atom** is called atomic number. It is represented by `Z`.
What does neutral mean here? Why doesn't he just say "..present in an atom is called..."? |
Someone gave me definition of atomic number as follows:
> The number of electron or proton present in a **neutral atom** is called atomic number. It is represented by $Z$.
What does neutral mean here? Why doesn't he just say "..present in an atom is called..."? |
Why or when does non-thermal plasma become thermal? How do we know before hand if the ion temperature will differ from the electron temperature, on what parameters does it depend - where is the quantitative gap between the two options?
(Has it to do with the heat release in ion-recombination reactions?) |
Some recent research I'm dealing with has required me to look for tables of experimental pressure/volume/temperature values (equivalently, a table of compressibility/compression factors in terms of any two of pressure, volume, or temperature) for various substances. Thus far, I've managed to obtain compression factor t... |
Where can I obtain tables of P-V-T/compression factor data? |
I know ***phenols are more acidic as compared to alcohols***, but are they considered different from alcohols?
Sure, you can study something as a subset, but are **phenols** considered a subset of alcohols, or are they considered as completely different from alcohols? My confusion is due to the fact that both of the... |
Is $CCl_4$ an electrolyte all by itself, or does something need to be added to it so that it becomes an electrolyte?
Also, is it *weak* or *strong*? |
Is carbon tetrachloride an electrolyte? |
I can't make heads or tails of information on the net, although there seems to be plenty of it, it seems contradictory.
Supposedly calcium carbonate is used in antacids, yet there are warnings about ingestion and contact with skin.
I need to handle it in pure powder form, I'm mainly concerned about skin contact, ... |
Looking at the [Material Safety Data Sheet (MSDS)](http://www.sciencelab.com/msds.php?msdsId=9927119), most of the issues with it seem to stem from the physical consequences of it being in fine dry powder form. This means that if you get it on your skin, it can get into cracks and pores and easily dry out your skin to ... |
I can't make heads or tails of the information on the net — although there seems to be plenty of it, it seems contradictory.
Supposedly, calcium carbonate is used in antacids—yet there are warnings about ingestion and contact with skin.
I need to handle it in pure powder form. I'm mainly concerned about skin cont... |
Synthesising $\ce {CH4}$ from air and water (in a non-biological process) has been proposed as one form of energy storage. What are the chemical constraints at play here? That is to say, **what sort of catalysts might be used, and what are the performance / lifetime issues with them?**
More specifically:
$\ce {CO... |
In Nuclear magnetic resonance (H-NMR) spectroscopy, the chemical shift of aliphatic hydrogen atoms are very much closer to the 1.0 ppm than that of aromatic hydrogen atoms.
When tetra methyl silane is used as a standard for NMR spectroscopy, aromatic hydrogen atoms have a chemical shift value of about 7.0-9.0 ppm wh... |
Why does aromatic hydrogen atoms have a higher chemical shift compared to aliphatic hydrogen atoms? |
Why does aromatic hydrogen atoms have a higher chemical shift value compared to aliphatic hydrogen atoms? |
In Nuclear magnetic resonance (H-NMR) spectroscopy, the chemical shift of aliphatic hydrogen atoms are very much closer to the 1.0 ppm than that of aromatic hydrogen atoms.
Aromatic hydrogen atoms have a chemical shift value of about 7.0-9.0 ppm whereas the chemical shift value of aliphatic hydrogen atoms ranges bet... |
Why do aromatic hydrogen atoms have a higher chemical shift value compared to aliphatic hydrogen atoms? |
I read in the local paper that common food products like turmeric can be adulterated. It continued to specify the adulterant which they called metanil yellow. On searching on the Net, I was able to find that metanil yellow is prepared using some basic raw materials like metanilic acid and diphenylamine. The paper conti... |
Energy-efficiency aside, what are the chemical constraints on $\ce {CO2}$ capture and methanation? |
Why do peroxides tend to explode with little provocation? In general, what are typical products of their explosion? |
Why are peroxides explosive? |
I remember that one of my old organic chemistry profs referred to mercury as being a "fancy proton". I think it was in the context of oxomercuration reduction. What gives? |
Why is mercury a "fancy proton"? |
I remember that one of my old organic chemistry profs referred to mercury as being a "fancy proton". I think it was in the context of oxymercuration reduction.
What might have been his rationale for offering this comparison? |
Energy-efficiency aside, what are the chemical constraints on CO2 capture and methanation? |
I'm only directly attacking your direct question, "what sort of catalysts might be used, and what are the performance / lifetime issues with them?" because the rest is ill-defined. I'll mention some electrochemical conversion aspects. I hope to illustrate why your question is problematic.
There are several different... |
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