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What is the difference between an angular and linear skeletal formula? |
When drawing a skeletal formula, what is the difference between an angular version and a linear version?
I was asked to draw the Z isomer of Resveratrol:
![(E)-Resveratrol][1]
For which I drew:
![My (Z)-Resveratrol][2]
However the markscheme states that:
> skeletal structure must be correct **and angular ... |
Can derive the quantity of a substance from a [GC/MS](http://en.wikipedia.org/wiki/Gas_chromatography%E2%80%93mass_spectrometry) report if I know:
* the ratio to another substance in the data,
* the quantity of that second substance, and
* the molecular mass of both substances.
The site was very dense an... |
The ideal gas equation (daresay "law") is a fascinating combination of the work of dozens of scientists over a long period of time.
I encountered Van der Waal's interpretation for non-ideal gases early on, and it was always somewhat in a "closed-form"
$${\bigl(p + \frac{n^2a}{V^2}\bigr)(V - nb) = nRT}$$
with $a$... |
When testing for pH for common household cleaning products, such as dishwasher fluid, I noticed that majority of them tend to be basic? Why is that? Do acid make good cleaning solutions as well? |
Why are the majority of cleaning solutions basic? |
I'll add to Aesin’s answer that in this case, the burden of proof rests on the side of an analytical (or closed-form) equation of state. Statistical mechanics explicitly guarantees that there is a relationship between $p$, $V$ and $T$, i.e. that they are not independent state variables. However, no further generic stat... |
Why are there no edge dislocations in an FCC lattice? |
Dishwasing agent Are mainly used to remove oil and protein based deposits from plates, glasses and other utensils
Dishwashing agents are usually anionic
Anionic detergents are alkylbenzenesulfonates.
They consist of two parts
1. Sulfonate part which is hydrophilic(water loving i.e. dissolves in water)
... |
The [Hammett plot][1] is commonly invoked in organic chemistry to reason about the plausibility (or implausibility) of various reaction mechanisms. The vertical axis is essentially the logarithm of an equilibrium constant (or rate constant) measured relative to a hydrogen functional group, which I understand. However, ... |
How are $\sigma$ and $\sigma^\pm$ determined in Hammett plots? |
Dishwashing agents are usually anionic detergents ie they are alkylbenzenesulfonates.
They consist of two parts
1. Sulfonate part which is hydrophilic(water loving i.e. dissolves in water)
2. Alkylbenzene part which is lipophilic(fat loving i.e dissolves in fats and oils)
Thus when in water they dis... |
When drawing a skeletal formula, what is the difference between an angular version and a linear version?
I was asked to draw the Z isomer of Resveratrol:
![(E)-Resveratrol][1]
For which I drew:
![My (Z)-Resveratrol][2]
However the markscheme states that:
> skeletal structure must be correct **and angu... |
What is the difference between melting and dissolving? I am looking some general features.
The answer should be adaptable to the melting/dissolving of ice cube (water) in a class of pure alcohol (ethanol) just below(or at the) melting point of ice, or similar phenomena.
I am now assuming that the ice is dissolv... |
What is the difference between melting and dissolving? I am looking some general features.
The answer should be adaptable to the melting/dissolving of ice cube (water) in a class of pure alcohol (ethanol) just below(or at the) melting point of ice, or similar phenomena.
I am now assuming that the ice is dissolv... |
QTPIE is a [fluctuating charge model](http://www.slideshare.net/acidflask/constructing-a-rigorous-fluctuatingcharge-model-for-molecular-mechanics) that substantially improves modeling of polarization and charge transfer. I was curious whether it has ever been applied to 1D metals such as polyacetylene to provide new pe... |
Has QTPIE ever been applied to 1D metals such as polyacetylene? |
<h2> Basic dishwashing agents? </h2>
- Some dishwashing agents contain substantial amounts of NaOH, see below.
- Sometimes NaClO solutions are used as disinfectant for dishwashing.
<br/>$\require{mhchem}$
As $\ce{Cl- + ClO- + 2 H+ <=>> Cl2 ^ + H2O}$, they are kept basic (and $\ce{Cl-}$free, but $\ce{3 ClO- ->... |
What kind of bonds silica bead forms with polystyrene? Silica is now as ~100 $\mu$m spherical particles in bulk polystyrene that is made by melting.
How can I bond the silica particles
1. more tightly
2. more loosely
to the polystyrene?
Can this be generalized to any nano/micro particle and plastics? I ... |
How is silica bead bonded into polystyrene? |
I have to stretch my memory to remember how this goes (and read a bit from [here][1]).
First, how do you define burgers vector? You take the end point of the dislocation and make a circle around it as it were a perfect lattice, the extra (or missing step) from the full loop is the burgers vector.
Now, is the bur... |
X-ray photoelectron spectroscopy ([XPS][1]) is a particularly useful technique for examining the surfaces of all sorts of materials. Organic monolayers are particularly difficult to characterize completely via this technique due to the fact that many carbon peaks do not differ much by chemical shift. Traditionally quan... |
X-ray photoelectron spectroscopy ([XPS][1]) is a particularly useful technique for examining the surfaces of all sorts of materials. Organic monolayers are particularly difficult to characterize completely via this technique due to the fact that many carbon peaks do not differ much by chemical shift. Traditionally quan... |
What is the difference between melting and dissolving? I am looking some general features.
The answer should be adaptable to the melting/dissolving of ice cube (water) in a class of pure alcohol (ethanol) just below (or at the) melting point of ice, or similar phenomena.
I am now assuming that the ice is dissol... |
I have the following question to solve:
Tungsten (W) and chlorine (Cl) form a series of compounds with the following compositions:
Mass % W Mass % Cl
72.17 27.83
56.45 43.55
50.91 49.09
46.36 53.64
If a molecule of each compound contains only one tungsten ... |
How to compute molecular formula? |
In the standard brown ring test for the nitrate ion, the brown ring is $$\ce{[Fe(H2O)5 (NO)]^{2+}}$$
In this compound, the nitrosyl ligand is positively charged, and iron is in a $+1$ oxidation state.
Now, Iron has stable oxidation states $+2,+3$. Nitrosyl, as a ligand, comes in many flavours, of which a negative... |
Why is iron in the brown ring compound in a +1 oxidation state? |
In “periodic table”, the adjective is related to the noun *period*, and comes from Ancient Greek *περίοδος* through French *périodique*. In “periodic acid”, it is formed from the prefix *per-* and *iodic* (like *peroxide* and *permanganate*).
[Wiktionary][1] lists their respective UK pronunciations of as `/pɪə(ɹ).iˈ... |
<h2> Basic dishwashing agents? </h2>
- Some dishwashing agents contain substantial amounts of NaOH, see below.
- Sometimes NaClO solutions are used as disinfectant for dishwashing.
<br/>$\require{mhchem}$
As $\ce{Cl- + ClO- + 2 H+ <=>> Cl2 ^ + H2O}$, they are kept basic (and $\ce{Cl-}$free, but $\ce{3 ClO- ->... |
I think your question implicates another question (which is also mentioned in some comments here), namely: Why are all energy eigenvalues of states with a different **angular momentum quantum number** $\ell$ but with the same **principal quantum number** $n$ (e.g. $3s$, $3p$, $3d$) degenerate in the hydrogen atom but n... |
In [a series of papers in the early 1980s](http://www.springerlink.com/content/g83871qw83n26152/abstract/), Michael Springborg explored an interpretation of the [Wigner phase space function](http://en.wikipedia.org/wiki/Wigner_quasi-probability_distribution) as an electron density in a six-dimensional $(q,p)$ phase spa... |
Is the Springborg 6D phase space model used in modern molecular orbital modeling? |
I'm reading a book on carbon nanotubes (P.J.F. Harris, Carbon Nanotube Science, to be specific) at the moment and puzzling about Stone-Wales or 5775 defects. This is where two adjacent carbons undergo a 90-degree rotation about their mutual centroid and generate a defect consisting of two five membered rings and two se... |
What does the charge distribution around a Stone-Wales defect look like? |
I have the following question to solve:
Tungsten (W) and chlorine (Cl) form a series of compounds with the following compositions:
Mass % W Mass % Cl
72.17 27.83
56.45 43.55
50.91 49.09
46.36 53.64
If a molecule of each compound contains only one tungsten ... |
My Sister asked me this:
> "Why is it that when we chew gum, it is soft and mushy to begin with , but slowly gets firmer and firmer like after 20 mins of chewing?"
I think it is because when we initially chew gum it has plenty of sugar causing rapid salivation and hence mushiness and the rubber polymer is very f... |
I'm reading a book on carbon nanotubes (P.J.F. Harris, Carbon Nanotube Science, to be specific) at the moment and puzzling about Stone-Wales or 5775 defects. This is where two adjacent carbons undergo a 90-degree rotation about their mutual centroid and generate a defect consisting of two five membered rings and two se... |
I think your question implicates another question (which is also mentioned in some comments here), namely: Why are all energy eigenvalues of states with a different **angular momentum quantum number** $\ell$ but with the same **principal quantum number** $n$ (e.g. $3s$, $3p$, $3d$) degenerate in the hydrogen atom but n... |
I googled a bit about what $\ce{AgNO3 + AlCl3}$ will become and found out the following:
$\ce{3AgNO3 + AlCl3 -> Al(NO3)3 + 3AgCl}$
But why? I know that $\ce{Ag}$ is higher up in the Reactivity serie than $\ce{Al}$ but that do not make sense to me in this problem... Is it because $\ce{Cl}$ is just one when $\ce{NO... |
For example — "high purity chloride salt of Zinc (ZnCl2.2H2O)" or "various concentrations of FeCl2.4H2O"
What does the number before H2O mean?
|
How to understand this form of writing the solution — ( Some salt • n H2O)? |
Le Châtelier's principle only states that a system previously at equilibrium will want to _stay_ at equilibrium - that is, if we perturb it, it will try to go back to equilibrium. This system is _initially not at equilibrium_, and therefore we don't need his principle.
I think the reaction proceeds because the forma... |
For example — "high purity chloride salt of Zinc (ZnCl₂ . 2 H₂O)" or "various concentrations of FeCl₂ . 4 H₂O". What does the number before H₂O mean?
|
How to understand this form of writing the solution: (some salt • n H₂O)? |
Le Châtelier's principle only states that a system previously at equilibrium will want to _stay_ at equilibrium - that is, if we perturb it, it will try to go back to equilibrium. This system is _initially not at equilibrium_, and therefore we don't need his principle.
I think the reaction proceeds because the forma... |
In this molecule, which is 3,5-dimethyl-4-carboxypyrazolate (unless I got it wrong):
![enter image description here][1]
I do not think there is free rotation around the bond indicated in red, because one can write a resonnance structure with significant reasonable weight where a double bond would be located betwe... |
<h2> Basic dishwashing agents? </h2>
- Some dishwashing agents contain substantial amounts of NaOH, see below.
- Sometimes NaClO solutions are used as disinfectant for dishwashing.
<br/>$\require{mhchem}$
As $\ce{Cl- + ClO- + 2 H+ <=>> Cl2 ^ + H2O}$, they are kept basic (and $\ce{Cl-}$free, but $\ce{3 ClO- ->... |
In [a series of papers in the early 1980s](http://www.springerlink.com/content/g83871qw83n26152/abstract/), Michael Springborg explored an interpretation of the [Wigner phase space function](http://en.wikipedia.org/wiki/Wigner_quasi-probability_distribution) as an electron density in a six-dimensional $(q,p)$ phase spa... |
Le Châtelier's principle only states that a system previously at equilibrium will want to _stay_ at equilibrium - that is, if we perturb it, it will try to go back to equilibrium. This system is _initially not at equilibrium_, and therefore we don't need his principle.
I think the reaction proceeds because the forma... |
Oxygen is not a fuel by itself, it's only the oxidant. Combustion involves a fuel (acetylene, for example) and an oxidizer (here, O2). So if you have _no fuel_, but _all oxidizer_, then what's left to burn? |
Pure oxygen does not burn. Oxygen is a _supporter_ of combustion, not a combustible material(fuel) itself.
Combustion reactions are as follows:
$$\text{combustible stuff} \ce{+ O2 -> } \text{various oxides}$$
Note that nitrous oxide ($\ce{N2O}$) is also a supporter of combustion, which means that you can use i... |
Oxygen is not a fuel by itself, it's only the oxidant. Combustion involves a fuel (acetylene, for example) and an oxidizer (here, O<sub>2</sub>). So if you have _no fuel_, but _all oxidizer_, then what's left to burn?
Combustion is just a name we give to certain reactions. The point to get here is that the burning a... |
This is one of the questions with which I have puzzled over, and can arrive at no definite conclusion. Why are strong acids or bases, such as H2SO4, HNO3, HCl, and NaOH not suitable primary standards?
How will their higher or lower pH affect the accuracy of the results of a titration? |
Why are strong acids and bases not suitable as primary standards? |
This is one of the questions with which I have puzzled over, and can arrive at no definite conclusion. Why are strong acids or bases, such as $\ce{H2SO4}$,$\ce{ HNO3}$, $\ce{HCl}$, and $\ce{NaOH}$ not suitable primary standards?
How will their higher or lower pH affect the accuracy of the results of a titration? |
What's the difference between precipitate and turbidity? |
[Slush hydrogen](http://en.wikipedia.org/wiki/Slush_hydrogen) is a mixture of liquid and solid hydrogen **at the triple point** considered as a possible vehicle fuel. What is the need of having it at the triple point? Couldn't any other set of thermodynamic conditions consistent with liquid–solid equilibrium work as we... |
Why is slush hydrogen at the triple point? |
I am not planning to do these types of experiments but I would like to know the order of magnitude of the time it takes to run an LC-MS/MS experiment. Let's assume that I have the sample prep (protein) finished and I just need to load the sample into the LC. How long would I need to wait before I would get MS/MS data?
... |
> Ag is higher up in the Reactivity serie than Al but that do not make sense to me in this problem
- indeed this is **no** redox problem, oxidation states do not change.
- instead the equilibrium is <br/>
$\ce{Ag+ + Cl- <=> AgCl v}$
As you marked this question as homework:
- Edit the question and put the... |
> Ag is higher up in the Reactivity serie than Al but that do not make sense to me in this problem
- indeed this is **no** redox problem, oxidation states do not change.
- instead the equilibrium is <br/>
$\ce{Ag+ + Cl- <=> AgCl v}$
As you marked this question as homework:
- Edit the question and put the... |
In “periodic table”, the adjective is related to the noun *period*, and [comes from](http://www.etymonline.com/index.php?term=periodic&allowed_in_frame=0) Ancient Greek *περίοδος* through French *périodique*. In “periodic acid”, it is formed from the prefix *per-* and *iodic* (like *peroxide* and *permanganate*).
[W... |
> Ag is higher up in the Reactivity serie than Al but that do not make sense to me in this problem
- indeed this is **no** redox problem, oxidation states do not change.
- instead it is a phase transition equilibrium
$$\ce{Ag+ + Cl- <=> AgCl v}$$
As you marked this question as homework:
- Edit the questio... |
> Ag is higher up in the Reactivity serie than Al but that do not make sense to me in this problem
- indeed this is **no** redox problem, oxidation states do not change.
- instead it is a phase transition equilibrium
$$\ce{Ag+ + Cl- <=> AgCl v}$$
As you marked this question as homework:
- Edit the questio... |
> Ag is higher up in the Reactivity serie than Al but that do not make sense to me in this problem
- indeed this is **no** redox problem, oxidation states do not change.
- instead it is a phase transition equilibrium
$$\ce{Ag+ + Cl- <=> AgCl v}$$
As you marked this question as homework:
- Edit the questio... |
> Ag is higher up in the Reactivity serie than Al but that do not make sense to me in this problem
- indeed this is **no** redox problem, oxidation states do not change.
- instead it is a phase transition equilibrium
$$\ce{Ag+ + Cl- <=> AgCl v}$$
As you marked this question as homework:
- Edit the questio... |
Please take a look at the following video:
http://www.youtube.com/watch?feature=player_embedded&v=f95bNFVZkh0
I am working on a new project, and i need to find whats the best liquid to hold ferrofluid inside the glass (or maybe even plastic) container, so that ferrofluid (that easily stains everything) does not sta... |
Please take a look at the following [video][1]:
[![Ferrofluid][2]](http://www.youtube.com/watch?feature=player_embedded&v=f95bNFVZkh0)
I am working on a new project, and i need to find whats the best liquid to hold ferrofluid inside the glass (or maybe even plastic) container, so that ferrofluid (that easily stai... |
Please take a look at the following [video][1]:
[![Ferrofluid][2]](http://www.youtube.com/watch?feature=player_embedded&v=f95bNFVZkh0)
I am working on a new project, and I need to find whats the best liquid to hold ferrofluid inside the glass (or maybe even plastic) container, so that ferrofluid (that easily stai... |
> Related: http://chemistry.stackexchange.com/q/383/22
Experimentally, $\ce{AgCl}$ is insoluble in water, but $\ce{AgNO3}$ is soluble. They're pretty common in a lab (well, $\ce{AgCl}$ is a common precipitate)--so I think most of us know this.
By [Fajan's rules][1], on the other hand, larger anion $\implies$ more... |
Why is $\ce{AgCl}$ less soluble than $\ce{AgNO3}$? |
[Hematite](http://en.wikipedia.org/wiki/Hematite) is composed of $\ce{Fe2O3}$, and is paramagnetic, whereas [magnetite](http://en.wikipedia.org/wiki/Magnetite) is $\ce{Fe3O4}$ and is diamagnetic. Magnetite's nature is due to the presence of both $\ce{Fe^{2+}}$ and $\ce{Fe^{3+}}$ (Wikipedia even goes so far as to call ... |
What is it about the relationship between the $\ce{Fe^{2+}}$ and $\ce{Fe^{3+}}$ in magnetite that makes it diamagnetic? |
I was told that "Sodium Tallowate, sodium cocoate and sodium palm kernelate are the 'natural' forms of [SLS][1]". Is this true? I thought "natural" SLS would be SLS derived from a natural product such as coconut oil.
[1]: http://en.wikipedia.org/wiki/Sodium_dodecyl_sulfate |
Is soap the natural form of Sodium Lauryl Sulfate? |
Dishwashing agents are usually anionic detergents—i.e. they are alkylbenzenesulfonates.
They consist of two parts:
1. Sulfonate part which is hydrophilic(water loving i.e. dissolves in water)
2. Alkylbenzene part which is lipophilic(fat loving i.e dissolves in fats and oils)
Thus, when in water, the... |
(-)-sparteine, in my experience, decomposes relatively quickly in ambient conditions. What is the reaction taking place to cause it to decompose? |
In [a series of papers in the early 1980s](http://www.springerlink.com/content/g83871qw83n26152/abstract/), Michael Springborg explored an interpretation of the [Wigner phase space function](http://en.wikipedia.org/wiki/Wigner_quasi-probability_distribution) as an electron density in a six-dimensional $(q,p)$ phase spa... |
By what reaction does (–)-sparteine decompose in ambient conditions? |
Lithium and magnesium are Group 1 and Group 2 elements respectively. Elements of these groups are highly ionic, and I've never heard of them forming significantly covalent _inorganic_ compounds.
Yet these elements form a variety of organometallic compounds ($\ce{PhLi}$, the whole family of Grignard reagents, etc). O... |
Why do Magnesium and Lithium form *covalent* organometallic compounds? |
I've been asked this question a few times, and while I _think_ I know the answer, I'd like to know more.
Graphite, as we know, is a sheet polymer. Since polymers are bound to be finite by physical considerations, graphite must have "edges". My question is, what happens at these edges?
I can cook up these poss... |
Oxygen is a rather boring element. It has only two allotropes, Oxygen and Ozone. Oxygen has a double bond, and Ozone has a delocalised cloud, giving rise to two "1.5 bonds".
On the other hand, Sulphur has many stable allotropes, and a bunch of unstable ones as well. The variety of allotropes, is mainly due to the... |
Why does Sulphur, but not Oxygen, catenate? |
In [a series of papers in the early 1980s](http://www.springerlink.com/content/g83871qw83n26152/abstract/), Michael Springborg explored an interpretation of the [Wigner phase space function](http://en.wikipedia.org/wiki/Wigner_quasi-probability_distribution) as an electron density in a six-dimensional $(q,p)$ phase spa... |
Lithium and magnesium are Group 1 and Group 2 elements respectively. Elements of these groups are highly ionic, and I've never heard of them forming significantly covalent _inorganic_ compounds.
Yet these elements form a variety of organometallic compounds ($\ce{PhLi}$, the whole family of Grignard reagents, etc). O... |
First, a note: while oxygen has fewer allotropes than sulfur, it sure has [more than two][1]! These include O, O<sub>2</sub>, <sup>1</sup>O<sub>2</sub>, O<sub>3</sub>, O<sub>4</sub>, O<sub>8</sub>, metallic O and four other solid phases. Many of these actually have a corresponding sulfur variant. However, you are right... |
To analyse such situations, you first must realize that nearly everything is present as ions. For example, if you took the reaction $\ce{NaCl +KBr->NaBr +KCl}$, the "direction" it goes in has no real meaning since $\ce{Na+}$, $\ce{Cl-}$, $\ce{K+}$, $\ce{Br-}$ are present as ions. There is no actual _reaction_ going on ... |
> Is dissolving always exothermic?
No, it is not always exothermic. For example, dissolving $\ce{NaOH}$ is an exothermic reaction, while dissolving $\ce{NH4NO3}$ is an endothermic reaction (This is from my personal experience)
> Is melting always endothermic?
Yes, it always is (except for the exceptio... |
Nitrile gloves are made of [**nitrile rubber**][1], or **poly(butadiene/acrylonitrile)**. This polymer is [highly soluble](http://www.polysciences.com/Core/Display.aspx?pageId=98&categoryId=114&productId=454) in chloroform, with some papers I found indicating that one can dissolve up to 18% in mass of nitrile butadiene... |
[Ortho- and parahydrogen][1] are two forms of the $\ce{H2}$ molecule that are distinguished by their pairing or antipairing of nuclear spins, giving rise to metastable singlet (ortho-) and triplet (para-) states. This constitutes an example of nuclear spin isomerism.
Whilst the thermal properties of these two specie... |
Are there any examples of nuclear spin isomers having consequences for chemical reactivity? |
The qualifier *'free'* seems to be ubiquitously attached to discussion of radicals as highly reactive species with unpaired spins. What, precisely (or imprecisely, as the case may be) does *'free'* really mean?
*<sub>Free as in free speech? Free beer? Freedom of movement? Kinetic accessibility?</sub>* |
What makes a radical 'free'? |
I'm attempting to perform atomistic optimal structure alignment on an inorganic species. Can anyone point me in the right direction to software or a technique for performing this?
There exists a wide range of structural alignment software, but this really appears to be geared towards aligning protein backbones, wher... |
How can I perform structure alignment on an inorganic species? |
The [R/S naming system](http://en.wikipedia.org/wiki/Chirality_(chemistry)#Naming_conventions) for stereocenters relies on the [Cahn–Ingold–Prelog priority rules][1] to rank the four substituents of a stereocenter; the R or S name is then attributed depending on the spatial orientation of the ranked substituents. While... |
How are non-carbon stereogenic centers named (S/R)? |
I'm attempting to perform atomistic [optimal structure alignment][1] on an inorganic species. Can anyone point me in the right direction to software or a technique for performing this?
There exists a wide range of structural alignment software, but this really appears to be geared towards aligning protein backbones,... |
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