# All Questions

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### May I treat units (e.g. joules, grams, etc.) in equations as variables?

Suppose I have two units, Tonks, $T$, and Borks, $B$, as well as the equation $\frac{50T}{20B}=x$. May I manipulate the equation as though $T$ and $B$ were the kinds of symbols that we learned to ...
3answers
6k views

### Has anyone even taken a picture of a molecule to confirm the geometry predicted by theory?

Have the geometries of molecules been proven, or are we operating strictly on mathematical theory? To put it over-simplistically: has anyone ever taken a picture of a molecule to compare against their ...
4answers
17k views

### Is pyrene aromatic despite failing Hückel's rule?

Pyrene doesn't seem to be aromatic. However, sources claim that it is aromatic. Considerations: Pyrene is cyclic. ✓ Pyrene is flat (planar). ✓ Pyrene has 16 π electrons. Every atom in the ring ...
3answers
5k views

### Why isn't 'chemically-strengthened glass' made with potassium carbonate to begin with?

Instead of making potassium-strengthened glass by creating ordinary soda-lime glass first, then replacing the sodium atoms/ions with potassium by putting the glass in a bath/solution of potassium ...
3answers
2k views

### Pauli exclusion principle and resonance

I've always been a bit uncomfortable with the concept of more than two electrons in a single orbital-like region(probability-wise) which occurs in resonance. This seems to disobey Pauli's exclusion ...
4answers
2k views

### Synthesis Golf II: Erythronolide B

A full FAQ post has been written on meta.chem.SE, explaining the premise of synthesis golf and the 'rules'. Please take a look at this if you haven't already. This round of synthesis golf concerns ...
4answers
4k views

### Why is the letter J omitted in the spdf... sequence?

Under spherical symmetry, the irreducible representations corresponding to $L = 0, 1, 2, \cdots$ are assigned the letters $\mathrm{S}, \mathrm{P}, \mathrm{D}, \mathrm{F}, \cdots$ after which the ...
6answers
23k views

### Why do chemistry and physics have different sign convention in thermodynamics?

In physics class, we write the first law of thermodynamics as $\mathrm dU =\mathrm dQ - \mathrm dW$ and in the physical chemistry class, we write the same law as $\mathrm dU =\mathrm dQ + \mathrm dW$. ...
3answers
2k views

### Proper typography of "NOx"

I am a journal typesetter, and recently I came to a problem that I'm not sure I know to solve. The question is how to properly typeset the "NOx" abbreviation for nitrogen oxides. Which is ...
2answers
42k views

### Why is gold unreactive when only one electron is in the outer shell?

I've been trying to answer my (high school) daughter's questions about the periodic table, and the reactivity series, but we keep hitting gaps in my knowledge. So I showed that the noble gases have a ...
3answers
11k views

### Does O2 have a color in the gas phase

I have noticed that liquid $\ce{O2}$ (I clarify it as $\ce{O2}$ because oxygen exists in several other forms which have different colors in the liquid state than $\ce{O2}$) has a light blue color to ...
2answers
106k views

### Chemistry behind Gale's coffee maker in Breaking Bad

Is there a scientific basis for the coffee making equipment which Gale Boetticher describes in Breaking Bad? He talks about maintaining the right conditions for bringing out the coffee flavor without ...
2answers
3k views

### Hypervalency and the octet rule

I realize that the octet rule is more a suggestion than a rule, and that it applies mainly to non-transition metal compounds. Still, compounds that don't have an octet, like $\ce{BH3}$, tend to ...
1answer
4k views

### What would follow in the series sigma, pi and delta bonds?

I realise, that this question is a stretch, but I was wondering, how would a bonding orbital be called if it was formed from two $f_{x(x^2−3y^2)}$ or $f_{y(3x^2−y^2)}$ orbitals. Have there been any ...
1answer
5k views

### Stereoselectivity of dihydroxylation with osmium tetroxide

Dihydroxylation responds to steric effects and proceeds at less hindered positions. What will be the major product in the following reaction if the reagent used is $\ce{OsO4}$ followed by $\ce{NaHSO3}$...
1answer
627 views

### Single-molecule magnet with electrically-controlled permeability: How does the Titan Shield from Deus Ex work?

In a recent installment of Deus Ex game series there is an augmentation called "Titan Shield" (it has nothing to do with $\ce{Ti}$ element): A neodymium skin underlay matrix built of nano-...
9answers
11k views

### Would it be possible to destroy gold?

I'm a writer. I have a scenario in which a sizable amount of gold needs to be rendered unusable, preferably completely destroyed. I know an acid like aqua regia is able to dissolve gold, but would ...
2answers
163k views

### What would be the effect of the addition of an inert gas to a reaction at equilibrium?

Why does a dissociation reaction shift to the right with the addition of an inert gas?
6answers
2k views

### Synthesis Golf I: Sodium Fluvastatin

A full FAQ exists on meta.chem.SE explaining the premise of synthesis golf, why we're doing this, and the ground rules. Please read this before posting an answer. The target for this first round of ...
4answers
14k views

### Why is methanol toxic?

There are two points of view for the answer of this question: The biological view, the only one that I faced during my research, states that since it can trigger perilous conditions like metabolic ...
2answers
169k views

### How do I extract cyanide from apple seeds?

I'm working on a crime story about cyanide poisoning from apple seeds. I just would like to have an idea of what processes and extraction techniques might be involved in getting cyanide from the seeds....
3answers
7k views

### Soaps come in different colors, but why is soap lather always white?

Soap comes in different colors, but why is soap lather always white?
4answers
110k views

### Tetrahedral or Square Planar

How can one predict whether a given complex ion will be square planar or tetrahedral when its coordination number is 4 using crystal field theory ? Is it possible to theoretically predict this?
5answers
15k views

### Why don't the electrons move through the electrolyte (instead of the circuit) in a galvanic cell?

I was learning about galvanic cells and I had a problem understanding why electrons do not travel through the electrolyte solutions themselves, instead preferring to travel through metals. Can ...
1answer
1k views

### Flammability (NFPA) - how is it defined?

I was reading up on a wonderful little chemical compound known as chlorine trifluoride ($\ce{ClF3}$). For a primer, check out Dr. Derek Lowe's blog post here: Sand Won't Save You This Time. The title ...
1answer
9k views

### When is it true that more nodes equals higher energy?

Consider all the MOs of some isolated molecule. (It could be a single atom too; I'll use MO to refer to AOs as well.) Number them in increasing order of the number of nodes (node = surface where the ...
3answers
34k views

### Why is the bond length of CO+ less than that of CO?

According to molecular orbital theory, the bond order of $\ce{CO}$ is 3. When $\ce{CO+}$ is formed, the bond order decreases to 2.5, and thus the bond length should increase. However, the bond length ...
3answers
35k views

### Why can't Pd/C and H2 reduce both the alkene and carbonyl portions of α,β-unsaturated carbonyls?

Why is it that the major product of the reduction of chalcones the ketone and not the monoalcohol? In other words, Why isn't the major product a benzyl alcohol? From what I understand, catalytic ...
1answer
3k views

### Is there an energy cost associated with flipping the spin of an electron?

THE STORY: A common example used to illustrate the limitations of restricted Hartree-Fock (RHF) theory is the H$_2$ dissociation energy ($D_e$) curves. RHF enforces electrons to be paired into spin ...
1answer
55k views

### Acidity of substituted phenols

Phenol has a $\mathrm pK_\mathrm a$ approximately equal to $9.9$. When one studies the acidity of chlorophenols, one notices the following: First of all, chlorophenols are more acidic than phenol, ...
2answers
1k views

### How does the silver nucleate on glass in Tollen's reagent mirroring?

I want to know the exact mechanism for how silver would start to grow during a mirroring with Tollen's reagent. I've made two pictures to illustrate how I see the nucleation/growth process of silver ...
4answers
12k views

### Effect of drinking ultra-pure water

What would be the effect if someone were to drink ultra-pure water with an electrical resistivity of $18 \, \mathrm{M} \Omega \! \cdot \! \text{cm}$? Would they immediately die? Would they just ...
4answers
8k views

### How are poisons discovered? Does someone have to die/be poisoned from it first?

How are poisons discovered? Does someone have to die/be poisoned from it first? Or are there other ways of discovering the harmfulness of a substance? Perhaps everything is tested on other animals ...
4answers
6k views

### Why are isotopes of hydrogen the only ones with special names?

Why does no other element but hydrogen get special names for its isotopes?
9answers
9k views

### Realistic chemical spill accident in high school chemistry class

In a story I'm writing, a teenager spills chemicals on herself in a high school chemistry class, causing her to be put under the safety shower. The spill destroys her clothes and causes minor burns. I ...
5answers
10k views

### Where did amino acids get their one-letter codes?

Some amino acids have a one-letter code that's just the first letter of the name of the amino acid. This makes sense and obviously, since there is more than one amino acid that begins with the same ...
1answer
8k views

### What caused the flashes in the video footage of Chernobyl?

There is video footage of nearby villages in Pripyat, in the first week after the Chernobyl disaster. When I watch it there are villagers leading normal lives in normal clothing. Some Russian nuclear ...
4answers
6k views

### How much CO2 could you remove from the atmosphere with 2 trillion USD?

I know it's possible to capture $\ce{CO2}$ with various chemical reactions. For example NASA's space shuttle had some kind of regenerative $\ce{CO2}$ scrubber. But how expensive is it? Could a huge ...
1answer
32k views

### Is the ammonium substituent (-NH3+) really meta-directing in electrophilic substitution?

If we make a resonance structure for the anilinium ion, with positive charge at either the ortho or the para position, we get a pentavalent nitrogen, which is not possible. So, how is the $\ce{-NH3+}$ ...
4answers
63k views

### What's the difference between a nucleophile and a base?

Obviously it depends on the context whether you would call a particular species a nucleophile or a base but are the two terms largely synonymous or is there a difference?
1answer
924 views

### Why does hyperconjugation help for ring cleavage?

The question was to rationalize it the ring cleavage happens concerted or non-concerted. The papers "The Mechanism of the Thermal Decomposition of 1-Pyrazolines and Its Relationship to ...
3answers
12k views

### Are there non-transparent gases?

Are there gases that are not transparent at room temperature (i.e. at temperature below the point where the substance starts to radiate visible light due to heating)?
3answers
130k views

### What are angular and radial nodes?

Nodes are the points in space around a nucleus where the probability of finding an electron is zero. However, I heard that there are two kinds of nodes, radial nodes and angular nodes. What are they ...
4answers
28k views

### What roles do neutrons play in an atom?

An atom typically consists of electrons, protons, and neutrons. Electrons are negatively charged and participate in bonding to stabilize the atom. Conversely, protons are positively charged and ...
3answers
24k views

According to Wikipedia, $\ce{HeH+}$ and fluoroantimonic acid are the strongest. According to Nature, Carborane acid is the strongest, but Wikipedia says fluoroantimonic acid is stronger. Links: $\... 3answers 35k views ### Why does burnt hair smell bad? When I use hot stuff like hair straightener on my hair, my hair begins to smell bad, which is very different from smell produced from burning other things. So what's the gas produced that is ... 2answers 80k views ### What are the meanings of dotted and wavy lines in structural formulas? So I came across this diagram,the other day: As a chemistry student, I am well-versed with the dashed and wedged lines, but I was wondering what the wavy and the dotted line represent? 1answer 4k views ### What is the molecular structure of xenon hexafluoride? Xenon hexafluoride,$\ce{XeF6}$, can be obtained by reaction of xenon with excess fluorine gas. What is the gas-phase structure of the molecule? What experimental evidence is there to support it, ... 3answers 60k views ### Why are covalent bonds directional? It is said that covalent bonds are directional, while ionic bonds are not. Why? Is it because of the orientation/directional properties of the overlapping orbitals? 4answers 69k views ### Why does pyrite form cubic crystals? Pyrite ($\ce{FeS2}\$) forms cubic crystals, like these ones: I know that the crystal structure is primitive cubic, but I don’t see how cubic structure on the molecular level translates to cubic ...

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