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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.
- sheets of lead are easily bent, and they stay so.
- For bigger pie... |
I hope to keep this short.
Metanil yellow is an *azo dye* synthesized from the coupling of metanilic acid and diphenylamine, as described [here][1]. Here's a sketch:
![metanil yellow][2]
Now, the thing with most azo dyes like metanil yellow is that when they are taken internally, liver enzymes or intestinal fl... |
"Take a glass rod and rub vigorously the wall of the flask"
The substance will crystallize out of the solution.
" take a fire polished stirring rod and etch (scratch) the glass of your beaker. The small pieces of glass that are etched off of the beaker serve as nuclei for crystal formation"
"But reaching back ... |
Is Ozone has a color? Some of them are saying ozone has a bluish color. Anyone can explain it scientifically.
|
Is Ozone(o3) gas Has a color? |
Does ozone have a color or is it colorless? I have heard that ozone has a bluish color.
Could someone explain this observation scientifically?
|
Does ozone(O3) gas have a color? |
Does ozone (O3) gas have a color? |
I got this question wrong on a test and I don't know why:
Question: Which conformation is more stable?
![enter image description here][1]
[1]: https://i.stack.imgur.com/qZYGP.png
ANSWER: the chair on the left is more stable.
I thought that the ring conformation has zero ring strain so i'm confused... |
Which cyclohexane is more stable? |
Before modern chemical techniques, say in the 19th century and earlier, how did (al)chemists determine whether a substance was an element or a compound? If it was a compound, how did they determine its molecular formula and structure? |
How were elements and molecular formulæ determined in the old days? |
I got this question wrong on a test and I don't know why:
> Question: Which conformation is more stable?
>
> ![enter image description here][1]
>
>
>
>
> Answer: the chair on the left is more stable.
I thought that the ring conformation has zero ring strain so I'm confused.
[1]: https://i.sta... |
Which cyclohexane conformation is more stable? |
Amines left out in the atmosphere will air-oxidize to give N-oxides, which typically have a yellow color. These N-oxides can decompose to give further byproducts. I would store your sparteine under nitrogen or argon atmosphere.
[edit to give examples and mechanism]
The reaction proceeds through a radical chain mech... |
The quick way of answering that unhelpful question is to look for *too many principal $C_n$ axes*. (Since the next step is to look for a principal axis anyway, this is a natural step to take.) In particular, you are looking for more than one axis of order > 2. A threefold axis with three twofold axes perpendicular to i... |
Grease & Thermal resistant cardboard for the foods industry? |
The quick way is to look for *too many principal $C_n$ axes*. (Since the next step is to look for a principal axis anyway, this is a natural step to take.) In particular, you are looking for more than one axis of order > 2. A threefold axis with three twofold axes perpendicular to it? Just $D_{3*}$ (where $* = d$, $h$,... |
Almost certainly, yes. Applications of modern organic synthesis methods have drastically shortened the synthetic routes for such previously "daunting" targets such as strychnine [see Vanderwal](http://totallysynthetic.com/blog/?p=2585), tetracyclines [Myers](http://www.chem.harvard.edu/groups/myers/page2/page4/page4.ht... |
This is more of a chemical engineering question, but technically physics encompasses chemistry and engineering as well, so I thought I'd give it a shot before I get shot down, so to speak.
So-- here's what I'm looking to accomplish. I'm trying to create something, and there is one portion of it which is far beyond m... |
A quick method for separating liquids? |
I'm looking for a way to take 3 separate liquids (liquids which function as paint-- they will all be different colors), put them together into a container, and then rapidly separate them back to distinct colors.
All the electrical engineering aspects of my project I can handle, but this portion is beyond me. Does an... |
The quick way of doing that first step in the flowchart is to look for *too many principal $C_n$ axes*. (Since the next step is to look for a principal axis anyway, this is a natural step to take.) In particular, you are looking for more than one axis of order > 2. A threefold axis with three twofold axes perpendicular... |
The only thing that comes to my mind is laminar flow.
Watch [this video][1] and tell me if that's something like what you're look for.
Problem is, you're not really separating "three liquids"...
[1]: http://www.youtube.com/watch?v=p08_KlTKP50 |
I had a discussion with my supervisor today after I was a touch careless pumping down a flask with a liquid nitrogen cold trap attached. I checked, and there are [reports of explosions][1] after running air through a liquid nitrogen trap.
Given this, why does liquid oxygen not condense when you leave an open dewer ... |
Why does oxygen not condense onto open dewers of liquid nitrogen? |
I have seen in a TV show that some guy uses dry ice (liquid co2) to make ice cream and in an another TV show,liquid nitrogen is used with tequila ;both are edible .I know that both gases are inert but whether these gases can be poisonous or create any side-effects to our body(may in larger concentrations) or not .If ... |
I have seen on a TV show that some guy uses dry ice (solid $\small\ce{CO2}$) to make ice cream and on an another TV show, liquid nitrogen ($\small\ce{N2}$) is used with tequila. Both are edible.
I know that both gases are inert, but could these gases (perhaps in larger concentrations) be poisonous or create any ... |
What is the effect on humans of using dry ice and liquid nitrogen as food additives? |
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 - ... |
Did you notice any change of colour (e.g. to brown) and/or the formation of gunk upon adding the 3M NaOH?
I'd assume one would have to boil it, but is the following scenario conceivable under your conditions:
1. alkaline hydrolysis of the acetaminophen (paracetamol) to p-aminophenol
2. aerial oxidation to the co... |
I am looking at two phase diagrams, one has axes of T and %MgClO4 in a H2O-MgClO4 mix, and the other has axes of T and relative humidity. The authors of the second phase diagram say "The stability diagram is modified from [the earlier phase diagram] by converting salt concentration to RH using the Pitzer model and param... |
Deliquescence/efflorescence: How can I convert between salt concentration and RH? |
I am looking at two phase diagrams, one has axes of $T$ and $\%\ce{MgClO4}$ in a $\ce{H2O-MgClO4}$ mix, and the other has axes of $T$ and relative humidity. The authors of the second phase diagram say "The stability diagram is modified from [the earlier phase diagram] by converting salt concentration to relative humidit... |
In some parts of the world food is stored with formalin so it looks fresh forever!! This is astonishing but true. As formalin is very bad for health and does damage kidneys and liver very quickly, I am looking for a way to remove it.
When I buy fish, I know it has formalin in it. Every fruit I bought has formalin. ... |
What is the difference between temperature and thermodynamic temperature? |
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..."? |
In some parts of the world food is stored with formalin so it looks fresh forever! This is astonishing, but true ([See refs here][1]). As formalin is very bad for health and damages kidneys and liver very quickly, I am looking for a way to remove it.
When I buy fish, I know it has formalin in it. Every fruit I boug... |
I'm a little confused what reaction count as inonization. Is there any requirement for the educts for example? Some references suggest that it's only an ionization if you produce charged atoms/molecules and it's dubbed detachment otherwise. Then "double ionization" wouldn't be possible, strictly speaking. (There is a r... |
What is the exact nomenclature of ionization? |
I'm a little confused as to what reactions are considered ionizations. Is there any requirement for the educts, for example?
Some references suggest that it's only considered an ionization if you produce charged atoms/molecules and it's dubbed detachment otherwise. Then "double ionization" wouldn't be possible, str... |
I'm a little confused as to what reactions are considered ionizations. Is there any requirement for the educts, for example?
Some references suggest that it's only considered an ionization if you produce additional charged atoms/molecules from the educts (and some processes are dubbed detachment, which intuitively ... |
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 - ... |
Is it possible to extract information on elemental ratios from X-ray photoelectron spectroscopy (XPS)? For example, I am reading a paper and in it they say that the carbon to oxygen (C:O) ratios of the four samples are 2.8, 2.9, 5.1, and 23.3. However, the authors do not provide the actual XPS spectra, not even in a ... |
I'm researching cyanide for a biology project and noted that one of the largest sources of carbohydrates in the tropics is the cassava root -- which I previously researched as a food that contains a cyanogenic glycoside that is metabolized into hydrogen cyanide.
Most of the sources I reviewed claimed that, while boi... |
I can't tell if the modifier "formal" applies only to "definition" or to "algorithm" also, in the first sentence of your question's body. In case any algorithm would do: this looks like a [pretty standard instance of the cycle-detection problem](http://stackoverflow.com/questions/261573/best-algorithm-for-detecting-cyc... |
I have processed a si/polymer hybrid using a silane coupling agent which I need to determine the energy gap / band gap. Would you please let me know the procedure to go about determining the band gap? |
How to find energy gap for a compound? |
So there is the [standard formation enthalpy](http://en.wikipedia.org/wiki/Formation_enthalpy) $\Delta H^0_f$ and there is also formation entropy.
Are there more (independend) quantities? Is there a theoretical structure where one can show one got all the conserved quantities associated with a chemical reaction? It... |
So there is the [standard formation enthalpy](http://en.wikipedia.org/wiki/Formation_enthalpy) $\Delta H^0_f$ and there is also formation entropy.
Are there more (independend) quantities? What about the heat capacity? Is there a general theoretical structure where one can show one got *all* the conserved quantities... |
So there is the [standard formation enthalpy](http://en.wikipedia.org/wiki/Formation_enthalpy) $\Delta H^0_f$ and there is also formation entropy.
Are there more (independent) quantities? What about the heat capacity? Is there a general theoretical structure where one can show one got *all* the conserved quantities... |
How to find band gap for a compound? |
How to find the band gap for a compound? |
On [this Wikipedia page][1], the electrical conductivity of various materials are given in the third column ($\sigma \text{ (S/m) at 20}^\circ \text{C}$). I am interested in the entry for **Carbon (graphite)**:
- $2$ to $3 \times 10^5 \text{ S/m} \perp \text{basal plane}$
- $3.3 \times 10^2 \text{ S/m} \paralle... |
Pointing out the stable conformations of cyclohexane was a major part of Barton's [Nobel Prize][1]. His original review is [here][2] (paywalled, but you can see the first page).
The topic is discussed by Henry Rzepa on his blog starting with a little history:
>Like benzene, its fully saturated version cyclohexane r... |
I know that standard latex and nitrile gloves don't stop common organic solvents such as DCM and acetone. However, I was reading a [Reddit thread][1] and there were comments that if you are coming into contact with solvents you are just wearing the wrong type of gloves. In a non-manufacturer specific fashion, what type... |
What type of gloves for various solvents? |
I know that standard latex and nitrile gloves don't stop common organic solvents such as DCM and acetone. However, I was reading a [Reddit thread][1] and there were comments that if you are coming into contact with solvents you are just wearing the wrong type of gloves. In a non-manufacturer specific fashion, what type... |
What type(s) of gloves are effective against DCM and acetone? |
I am looking at two phase diagrams, one has axes of $T$ and $\%\ce{MgClO4}$ in a $\ce{H2O-MgClO4}$ mix, and the other has axes of $T$ and relative humidity. The authors of the second phase diagram say "The stability diagram is modified from [the earlier phase diagram] by converting salt concentration to relative humidit... |
I'm planning to do an experiment where I extract burnt toast and test how that affects the growth of mung beans. I know burnt food contains PAHs, but what are some other chemicals present and how would they affect plant growth? |
What chemicals are present in burnt toast? |
Is there a quick way to determine if a salt (or ionic compound in general) crystal should be birefringent from its formula without having to know/look up the crystal structure? When I'm looking for protein crystals, if I know the condition has a lot of salt in it, but it shouldn't be birefringent (e.g. NaCl), it's a h... |
What salts are/are not birefringent? |
I just did a bit of an experiment. My lab uses [Kimberly Clark nitrile gloves][1], and we have a huge jug of acetone. First, I put a glove on my hand, and poured acetone all over it. My hand felt cold, but not nearly as cold as it feels when I spill acetone on my bare hand. I allowed the acetone to evaporate from the g... |
This question is sort of a sequel to [my previous question about cyclic voltammetry (CV)][1]. One of the responses made reference to the fact that an ideal capacitor gives rise to a rectangular cyclic voltammogram. Can you please help me understand why this is the case? In other words, why does an ideal capacitor re... |
Why does an ideal capacitor give rise to a rectangular cyclic voltammogram (CV)? |
This question is sort of a sequel to [my previous question about cyclic voltammetry (CV)][1]. One of the responses made reference to the fact that an ideal capacitor gives rise to a rectangular cyclic voltammogram. Can you please help me understand why this is the case? In other words, why does an ideal capacitor re... |
Hey guys I'm confused about the octet rule - as far As I understand you need to complete the valance shell of the elements by sharing electrons. Now carbon has 6 electrons which means it has 4 valance electrons because it has 6 electrons in total it exceeds the first shell with 4 electrons. The second shell has 4 orbit... |
I'm confused about the octet rule. As far as I understand, you need to complete the valence shell of the elements by sharing electrons.
Now, carbon has 6 electrons which means it has 4 valence electrons, but because it has 6 electrons in total it exceeds the first shell with 4 electrons. The second shell has 4 orb... |
In nearly all default parameter sets for 2D NMR experiments on Bruker spectrometers, the window function is set to a pure sqared cosine function for both dimensions (`QSINE` with `SSB = 2`). In contrast to that, 1D spectra are often processed with the `efp` command, which uses an exponential window function.
Why is ... |
Why is a sqared cosine window function commonly used for 2D spectra? |
In nearly all default parameter sets for 2D NMR experiments on Bruker spectrometers, the window function is set to a pure squared cosine function for both dimensions (`QSINE` with `SSB = 2`). In contrast to that, 1D spectra are often processed with the `efp` command, which uses an exponential window function.
Why is... |
Why is a squared cosine window function commonly used for 2D spectra? |
For the first part of your question, you are correct that Mg has 12 electrons, which are arranged in shells in the pattern 2 - 8 - 2. But magnesium is a typical metal in that it tends to lose electrons to form a cation that then forms solids by ionic bonding. The octet rule predicts that the resulting cation will be st... |
In a [recent question][1] it was explained that Gaussian window functions are not used in 2D NMR spectra as they can introduce artifacts into the spectrum baseline by truncating the FID. Why then are they used with 1D spectra instead of sin or cosine functions?
[1]: http://chemistry.stackexchange.com/questions/8... |
Why is the Guassian Window Function used to enhance resolution in 1D NMR spectra? |
Mixing solid copper, 5% vinegar, and hydrogen peroxide (H2O2) causes copper acetate to form. The process will occur very slowly without hydrogen peroxide. Adding H2O2 speeds the formation of copper acetate. How does Hydrogen Peroxide promote the formation of Copper (II) Acetate?
|
What Role Does HOOH Have In Copper (II) Acetate Formation? |
I allways hear that some big corporations use "diamond dust" to filter water 7 times to make "diamond clear" vodka. I tried googling something about using diamonds for filtering but could not find anything except corporate sites that tell us only the best things about "diamond dust filtration technology"
Is this jus... |
Diamond filtering - is it real or bogus? |
I always hear that some big corporations use "diamond dust" to filter water 7 times to make "diamond clear" vodka. I tried googling something about using diamonds for filtering but could not find anything except corporate sites that tell us only the best things about "diamond dust filtration technology"
Is this just... |
Why is the Gaussian Window Function used to enhance resolution in 1D NMR spectra? |
I need to set a number of threaded bars into cement, to hold a new gatepost. When I cut the bar into shorter pieces, the metal near the cut became red hot, presumably hot enough to evaporate some or all of the zinc with which the entire rod was plated.
Now I want to plate zinc back onto the ends, and have had mixed ... |
The most common drying agent I encountered when using a vacuum dessicator was phosphorus pentoxide in the form of Sicapent. But I've recently encountered people using KOH as a cheaper alternative (in a practical course for students, where such costs are amplified due to the high number of students).
What are the dif... |
Differences between KOH and phosphorus pentoxide as drying agents? |
In certain applications some sorts of stainless steel (V2A, 1.4301) corrode when exposed to $Cl^-$ in water, or at least it is strongly advised to use other steels.
The conditions that were explained to me as beeing especially bad were: redox potential >0, acidic environment.
Now, under these conditions, why do I n... |
Why does Chloride corrode steel under certain conditions? |
Mixing solid copper, 5% vinegar, and hydrogen peroxide ($\small\ce{H2O2}$) causes copper acetate to form. The process will occur very slowly without hydrogen peroxide. Adding $\small\ce{H2O2}$ speeds the formation of copper acetate.
How does Hydrogen Peroxide promote the formation of Copper (II) Acetate?
|
In certain applications some sorts of stainless steel `(V2A, 1.4301)` corrode when exposed to $\small{Cl^-}$ in water, or at least it is strongly advised to use other steels.
The conditions that were explained to me as being especially bad were: redox potential >0, acidic environment.
Under these conditions, why ... |
Has anyone come across a scientific study of the S-Plasma Ions that Samsung claims will purify air from microbes, allergens and free radicals? I would prefer publicly available research findings. |
In certain applications some sorts of stainless steel `(V2A, 1.4301)` corrode when exposed to $\small{Cl^-}$ in water, or at least it is strongly advised to use other steels.
The conditions that were explained to me as being especially bad were: redox potential >0, acidic environment.
Under these conditions, why ... |
What is the difference in purity betwen lab-grade and food-grade when talking about potentially consumable compounds?
As an example let's take ascorbic acid powder: if it's marked as lab-grade, **does that mean it is also fit for consumption?**
I.e. does lab-grade supersede (and better) a food-grade labeling, or ... |
Difference between lab-grade and food-grade purity? |
I will be using trimethyl tin chloride (1M in THF) in a few days for the first time. Looking at the MSDS, it looks like it is very toxic and has noxious vapors. Are there any more tips for working with it other than the usual?:
- Check for proper airflow in the hood
- Wear lab coat, safety glasses, and double glo... |
How can I be safe and protect myself using trimethyl tin chloride? |
I have a number of [Chemical Table files](http://en.wikipedia.org/wiki/Chemical_table_file) which include a "M ZZE" tag in the properties block.
For example, in [Galactobuxin](http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=85296601), I have:
`M ZZE 1 31 23`
In [Rubrobrassicin](http://pubchem.ncbi... |
What does the ZZE tag in an Chemical Table file refer to? |
I have a number of [Chemical Table files](http://en.wikipedia.org/wiki/Chemical_table_file) which include a "M ZZE" tag in the properties block.
For example, in [Galactobuxin](http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=85296601), I have:
`M ZZE 1 31 23`
In [Rubrobrassicin](http://pubchem.ncbi... |
I happened to stumble upon [this Nature Chemistry article][1] today. It claims that
> [...] use a 3D printer to initiate chemical reactions by printing the reagents directly into a 3D reactionware matrix, and so put reactionware design, construction and operation under digital control.
Unfortunately, I cannot obt... |
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