ssavec
  • Member for 8 years, 2 months
  • Last seen more than a month ago
1 answers
3 votes
690 views
Are all organic molecules with odd-numbered electron count radicals?
Accepted answer
4 votes

By IUPAC definition of radical, the organic molecules with odd number of electrons must have at least one of them unpaired and are therefore radicals. The fundamental reason is the definition. Bear ...

View answer
4 answers
12 votes
8k views
Why do solutions become saturated?
Accepted answer
4 votes

Take a slightly more general problem of miscibility, all that in thermodynamic equilibrium. In your question you mix up kinetics and equilibrium, and additionally in a wrong way. Equilibrium is the ...

View answer
2 answers
3 votes
4k views
Why are wave functions orthogonal?
Accepted answer
4 votes

In general, orthogonal wavefunctions are much easier to treat. In some cases they appear naturally, but usually, the orthogonality is imposed as a constrain while constructing the wavefunction. For ...

View answer
1 answers
4 votes
3k views
Torsion angle symbol
4 votes

It is a habit to assign greek letters (most often lowercase) to angles. In case of "normal" angles, it's mostly $\alpha, \beta, \gamma$, whereas for dihedrals some higher letters, as you mentioned, $\...

View answer
2 answers
3 votes
7k views
Yellow-amber debris above water filter: What is it?
Accepted answer
4 votes

It looks like ion exchange resin, it is used to specifically capture ions from water and replace them by others (either $\ce{H^+}$ or alkali metal ions. As such, it is probably also part of the ...

View answer
1 answers
4 votes
119 views
Photochemical ligand substitution of metal carbonyls - role of water cooled lamp-jacket?
Accepted answer
4 votes

The main point is to stop the heat flow from the lamp, while allowing UV through. You want to do photochemistry, not thermochemistry.

View answer
1 answers
1 votes
147 views
What does "/2" in the structure of calcium benzoate mean?
Accepted answer
4 votes

It means half of calcium. The organic acid is $\rm{COO}^-$, whereas calcium is $\rm{Ca}^{2+}$. For the structure to be fully correct, there are two benzoic acids per one calcium. Other way round this ...

View answer
3 answers
15 votes
5k views
CO2 removal from mushroom growing tent
Accepted answer
3 votes

Please stay away from sodium hydroxide, it's way too nasty to use in non-lab setup. You can handle it safely in dry conditions, but in contact with water, it becomes sticky and causes bad burns. As a ...

View answer
3 answers
1 votes
2k views
Can electrons be present outside orbitals. If yes how does this affect chemical reactions
3 votes

There are more levels of abstraction involved. At first, orbitals are simplification and they are best described as "one electron wavefunction", ie. area of space where one electron can reside (or two,...

View answer
2 answers
1 votes
51 views
Where can I find a collection of density functional parameterizations?
Accepted answer
3 votes

Unless you are doing it just for fun and curiosity how the think works, you are better with some existing library. Most prominent is the libxc, offering the lowest level interface, i.e. given density (...

View answer
2 answers
2 votes
523 views
Work in free expansion
Accepted answer
3 votes

Little bit tricky question. As you say, the work is force acting along the path. But there is no force acting, as there is weightless piston with vacuum on the opposite side. To visualize the process ...

View answer
1 answers
7 votes
1k views
Predicting incomplete combustion?
Accepted answer
3 votes

Before entering the kinetics realm, it is advisable to check the equilibrium. Besides the straightforward combustion reactions, you have two more, Boudouard reaction, which favors formation of $\ce{CO}...

View answer
1 answers
6 votes
1k views
Does water vapor in the air oxidize copper?
3 votes

Although $\ce{H_2O}$ contains oxygen, it is there in the most reduced state $\ce{O^{2-}}$ and therefore cannot act as oxidizer. It is the oxygen in the air $\ce{O_{2}}$, which is the main and ...

View answer
2 answers
-1 votes
2k views
Most Comprehensive Chemistry Book(s)?
Accepted answer
3 votes

For the inorganic chemistry I recommend Holleman-Wiberg's text, also exists in english. It is reasonably readable and very thick and contains a lot. Holleman-Wiberg's Inorganic Chemistry. If you ...

View answer
2 answers
9 votes
2k views
Reaction Pathways: What to do when IRC geometries are relaxed (optimized) and the energy changes significantly
3 votes

The IRC algorithm usually follows the gradient from TS to product state B and by definition has to go always downhill in energy. In best case, it treats the Potential Energy Surface (PES) around the ...

View answer
1 answers
4 votes
7k views
What does the subscript of atomic orbital mean?
3 votes

For each azimutal quantum number $l$, the magnetic quantum number $m$ ranges from $-l$ to $+l$. Those give you the number of atomic orbitals "subsripts" you should obtain. Those are then expressed ...

View answer
2 answers
4 votes
3k views
Internal vs external steam distillation
3 votes

The main purpose is to distill the component (essential oil) with quite high boiling point. You have to think of distillation of immiscible liquids, http://www.chemguide.co.uk/physical/phaseeqia/...

View answer
1 answers
2 votes
214 views
Changes in defects in a material due to heat treatment
Accepted answer
3 votes

It seems, that your oxide can have different crystal polymorphs and probably also other non-crystalline phases. You synthesize your material as mixture of those, where the composition depends on the ...

View answer
2 answers
2 votes
7k views
How to interpret a MALDI mass spectrum?
Accepted answer
3 votes

Please see the wiki articles for the general method: http://en.wikipedia.org/wiki/Mass_spectrum http://en.wikipedia.org/wiki/Matrix-assisted_laser_desorption/ionization http://en.wikipedia.org/wiki/...

View answer
4 answers
5 votes
26k views
Why is it important that glucose’s third OH group points to the left?
2 votes

The wiki article on glucose states that more than 99% of the glucose molecules do exist in it's cyclic, pyranose, form. If you have a look at the cyclic form, you'd see that all -OH groups are ...

View answer
5 answers
9 votes
6k views
Is there a database on chemical reactions, similar to NIST, but far more complete?
2 votes

I use the www.reaxys.com most often, as it is really simple to use. See comparison of similar solutions at: http://www.infotoday.com/OnlineSearcher/Articles/InDepth-Reports/Apples-and-Oranges-A-...

View answer
3 answers
6 votes
2k views
Why does symmetry have to be maintained in molecular orbitals?
2 votes

The orbital and geometrical symmetry are closely related. You know that $\ce{XeF_4}$ is square planar, therefore $\ce{D_{4h}}$ symmetric. That also means that the four fluorine atoms are ...

View answer
2 answers
5 votes
1k views
Why does water change phase so easily?
2 votes

Vapor pressure of water is quite small, thanks to H-bonding in the liquid. Therefore more energy is needed to evaporate (break H-bonds with neighboring molecules) a water molecule. If you compare ...

View answer
4 answers
11 votes
3k views
Does radioactivity affect chemical reactions?
Accepted answer
2 votes

During the nuclear reaction, the atomic number Z (and therefore chemical identity) changes (transmutation). In your example, $\ce{RaCl_2 -> \alpha^{2+} + RnCl_2^{2-} -> He + RnCl_2}$. Radon ...

View answer
3 answers
3 votes
2k views
Alternatives to Ring Stands
Accepted answer
2 votes

What about puting the whole stand on the lab-lift, hopefully there will be also some precision version.

View answer
1 answers
3 votes
575 views
How can I avoid crystallisation of sugars in vinegar at low temperatures?
Accepted answer
2 votes

It is difficult to correctly measure the solubility, especially if it goes to multicomponent solutions, as your vinegar. It is possible to find tables with some components of your mixture, but you won'...

View answer
1 answers
3 votes
2k views
Are orbitals always filled in from closest to nucleus to farthest away?
2 votes

As you have studied for the quiz, you should know the expected answer. In full-scope reality, the question has nothing to do with the two explanations you offered, but with the shape of atomic ...

View answer
1 answers
3 votes
3k views
Calculate vapor pressure from volume
2 votes

You should treat everything as ideal gas. Then you calculate the volume change from the air itself, using ideal gas law and pressure being constant (atmospheric, maybe). Calculate also the number of ...

View answer
2 answers
6 votes
3k views
Why sponge can't absorb mercury
2 votes

You are asking wrong way. Sponge does not absorb almost anything. Apples, sand, dust, wires,... The point is: Why can sponge absorb water? Because the interaction of water and the sponge are ...

View answer
1 answers
3 votes
123 views
How do I start studying chemical nomenclature?
2 votes

Chemical nomenclature is mixture of historical traits, empirical knowledge and little bit of systematics. And as you mentioned, it is exhaustive to learn all at once. To understand the nomenclature, ...

View answer