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6
votes
1answer
830 views

What kind of chemicals would exist at the heat death of the universe?

As the universe reaches the maximum entropy, presumably only the most stable chemicals would exist. Assume that all the elements haven't turn into iron yet, what kind of chemicals would dominate at ...
2
votes
0answers
28 views

How is the thermal stability of nitric acid related to its structure?

How is the thermal stability of nitric acid related to its planar structure? In textbooks it is written that nitric acid is unstable at room temperature and decomposes where $\ce{H2SO4}$ and ...
9
votes
2answers
600 views

By what mechanisms can molecules with the same empirical formula be so different?

I understand the difference between empirical and chemical formula. But I always thought that compounds and molecules took their specific shape because it's the lowest energy configuration. How then, ...
4
votes
3answers
937 views

Is a single atom stable?

It is well known that single atom of oxygen is not stable, and it forms $\ce{O2}$ molecule. But elements like carbon form a network of repeated bonds. As answered in another question, last atoms in ...
11
votes
4answers
306 views

Why are DCM and Chloroform so resistant against nucleophilic substitutions?

In the book Organic Chemistry by J. Clayden, N. Greeves, S. Warren, and P. Wothers I found the following reasoning: You may have wondered why it is that, while methyl chloride (chloromethane) ...
1
vote
0answers
40 views

Is Oxide Anion more stable than O^+

O likes to be negative if charged at all. Most metal oxides are of the form $\ce{A^{x+} O^{2-}_{x/2}}$ (where $x$ is the magnitude of the positive charge and $\ce{A}$ is a metal.) Here, despite the ...
3
votes
2answers
96 views

How can two electrons lie together in an orbital?

Two electron of opposite spin can lie in a single orbital.. But what about the electron-electron repulsion. Okay! I got that the nuclear charge rather the large Z-effective overcome this repulsion by ...
1
vote
2answers
217 views

How does chlorine form more than 1 bond?

How are perchlorate or chlorate or chlorite ions and their respective acids or compounds formed. $\ce{Cl}$ can't form more than one bond but still... $\rightarrow$'Perchlorate ion' ...
2
votes
1answer
45 views

Conformational analysis determining forces

So the determining forces in the conformational analysis (what will be the more stable state and what will be the more excited state) according to my textbook are: Steric interaction Electron ...
4
votes
2answers
184 views

Why is O2 a biradical?

$\ce{O2}$ has a double bond in its normal form. That is $\ce{O=O}$. There are no unpaired electrons in this case are there since there are 2 lone pairs on each oxygen. However 1 resonance structure ...
1
vote
1answer
35 views

Why do all medicines require storage temperatures below 25 °C?

Almost all medicines I buy have storage requirements saying $T\le25^\circ C$. But do they really spoil at higher temperatures? What if they are stored at e.g. $30^\circ C$, which is common at ...
5
votes
1answer
107 views

What stable arrangements of hydrogen-bonded water exist in the range of 4-20 water molecules?

Water clusters made up of various numbers of water molecules have been described. Are all of these structures theoretical? What experimental evidence supports any of these structures? How does the ...
7
votes
1answer
288 views

Is BCl₅ possible?

Is $\ce{BCl5}$ possible? I saw it in book. As far as we can see there is no way to get 5 chlorine atoms with boron.
0
votes
1answer
29 views

Is there a possible effect of low frequency mechanical vibration on the stability of organic molecules

Is there a possible theoretical effect of mechanical vibration on the stability of organic molecules. E.g. some medicines degrade if they are not stored in a fridge, is there a theoretical ...
3
votes
1answer
128 views

Why is N₂ stable but HCN and C₂H₂ unstable?

Compounds with triple bonds generally seem to be unstable. $\ce{HCN}$ and $\ce{C2H2}$ are high-energy, relatively short-lived molecules that will readily polymerise or react with other organic ...
1
vote
1answer
39 views

Why is Technetium unstable?

Technetium is probably the most awkward element of the periodic table for me. It seems to me that Technetium is an exception, in the sense that it doesn't have any stable isotopes, despite having a ...
2
votes
2answers
129 views

Acidity of aldehydes

Which is more acidic between methanal ($\ce{HCHO}$) and ethanal ($\ce{CH3CHO}$). Please explain using General organic chemistry basic concepts. My Effort: I saw the stability of the conjugate base. ...
1
vote
2answers
61 views

How can a phase be thermodynamically stable at room temperature if it only appears at high temperature?

How can a phase that appears at high temperature be thermodynamically stable at room temperature? For example, $\alpha$-alumina is a phase that is formed at temperatures above $1000^\circ C$. How is ...
1
vote
2answers
65 views

Stability of transition metals in aqueous solution

Which is more stable in aqueous solution $\ce{Cr^{3+}}$ or $\ce{Mn^{3+}}$? And why? My approach: $\ce{Cr^{3+}}$ should be more stable as the 3d electrons will enter the $t_{2g}$ orbitals. Due to CFSE ...
5
votes
3answers
268 views

Stability of cyclobutyl methyl carbocation

I know that cyclopropyl methyl carbocation is exceptionally stable compared to say, benzyl carbocation. But I want to know how stable is cyclobutyl methyl carbocation compared to say, ...
3
votes
1answer
137 views

Thermodynamic stability of benzene ring

In learned that when benzene undergoes hydrogenation, $208KJ$ of energy is given off and thus $152KJ$ less energy than what would be given off if Kekule's structure was correct. My confusion is that ...
1
vote
2answers
107 views

delocalised electrons and benzene's stability

In most high school chemistry books, it is said that the delocalised electrons in benzene makes it particularly stable. However, how does it contribute to stability? Is there any simple way of ...
4
votes
1answer
165 views

Variable oxidation state of transition metal ions

Transition metals can form stable ions with different oxidation states. But I am confused why doesn't only the most stable state exist. Let me clarify my question more: $$\ce{Ti^{2+} -> Ti^{3+} + ...
1
vote
1answer
126 views

Why Fe(CO)5 exists, but Fe(NH3)5 doesn't?

Like in title: Why $\ce{Fe(CO)5}$ exists, but $\ce{Fe(NH3)5}$ doesn't? Edit: As Jan Dvorak pointed out, it may exist. If so: why is it so unstable?
2
votes
1answer
259 views

Stability of Allenes and Alkynes,

In Allenes, the $\ce{C=C=C}$ structure makes sure that the $p$-orbital of central carbon overlaps with 2 other carbons and the $p$-orbital of central carbon spreads out over the 3 carbons. In ...
5
votes
3answers
147 views

Why are noble gases stable

I was recently asked the question "Why are noble gases stable? with the expectation of providing an answer beyond the general explanation of "they have full valence layers" and I couldn't think of ...
7
votes
1answer
612 views

Resonance stability: ester vs. thioester

My problem set solution cites: "Although sulfur is less electronegative than oxygen, overlap is a more important consideration. Sulfur is a member of the third period. As a consequence, a ...
2
votes
1answer
171 views

Which is most stable conformation of optically inactive Butane–2,3–diol?

The most stable conformation of optically inactive Butane–2,3–diol is: (A) (B) (C) (D) I choose C as the correct answer but, in the answer key it given to be B. C is the staggered form and the ...
8
votes
3answers
911 views

Is oxygen with a positive charge more stable? (comparison of canonical structures)

Which of the contributing structures of the resonance below is more stable? I'm watching a video lecture by a professor of my college where he puts this question to the class. The class ...
8
votes
1answer
134 views

Phenyl vs methyl cis/trans stability

Compound I is obviously the Z isomer. I thought it was obviously the less stable one too, given that there's a phenyl and t-butyl on the same side. The answer says that since the phenyl is planar, ...
3
votes
2answers
168 views

Lone pair electrons on secondary carbon vs primary carbon

I know that a molecule is more stable when a free radical is on a secondary carbon over a primary carbon, but how about when there is a lone pair of elections that can be placed on a secondary or ...
3
votes
3answers
76 views

Are sulfonyl-carboxylates stable in water?

This time I am interested in a specific type of acid anhydride, sulfonyl-carboxylates, i.e. compounds with the following molecular structure: where R1 and R2 are organic substituents or hydrogen ...
2
votes
3answers
126 views

Are dicarbonyl amides stable in water?

Dicarbonyl amides, that is carboxylic acid anhydrides with their single-bonded oxygen between their carbonyl groups replaced with an amide group, I'm curious as to whether they're stable in water or ...
3
votes
1answer
186 views

Is it possible to create an acid anhydride that's stable in water and if so what conditions must its structure satisfy?

I ask this question because if acid anhydrides are always unstable in water then my interest, as a student of pharmacology, would be greatly diminished. Acid anhydrides are, in my books, at least, the ...
2
votes
1answer
490 views

What does reaction exothermicity say about the stability of molecules

If a reaction is exothermic it means that the energy state of the products is lower than that of the reactants so this will be the state that 'nature' will naturally strive for. Often you see that ...
6
votes
3answers
2k views

Normal Spinel and Inverse Spinel

According to my notes, [OCTAHEDRAL SITE STABILIZATION ENERGY (OSSE)], sterical effects and electronic effects in stability create a confusion in this theory. However, we are able to solve this problem ...
8
votes
5answers
17k views

Difference between thermodynamic and kinetic stability

What is the difference between thermodynamic and kinetic stability? I'd like a basic explanation, but not too simple. For example, methane does not burn until lit -- why?
12
votes
1answer
236 views

What are the g-block's predicted properties?

I have been researching for a Physics/Chemistry exam and thought; what will the future periods in the periodic table (periods 8 and above) would entail? Each block contains its own properties that ...
5
votes
2answers
520 views

Is this the lowest chair conformer of Beta D-galactose

I drew the conformer (below) and I'm wondering if this is the most stable chair conformation. Three of the bonds are equatorial so it looks like the most stable to me.
3
votes
1answer
413 views

Why are noble gases stable?

Generally, noble gases are very unreactive. Why? I understand that it has to do with electron shielding prospective electrons that could join the atom or leave and the energies associated with both ...
4
votes
1answer
124 views

Why not “Oxygate” OO4(2-)?

So many atoms can be surrounded by oxygen atoms to make anions - chromate, phosphate, etc. In particular there's Tellurate TeO4(2-), Selenate SeO4(2-) and Sulfate SO4(2-) - why not go one step more ...
5
votes
1answer
375 views

Why is a sodium metabisulfite-starch-HCl solution unstable?

In one variation of the Iodine Clock Demonstration, you add two colorless solutions together and apparently nothing happens. After about 30 seconds to a minute, you get an "instantaneous" change to a ...
3
votes
1answer
990 views

The most stable furan resonance structures?

I want to know which are the most stable furan resonance structures. I know that structure number 1 is the most stable, but which one comes after?
7
votes
1answer
481 views

What dictates the lifetime of a solvated electron in a given solvent?

Solvated electrons have a long lifetime in ammonia solutions, but their counterparts in water (called hydrated electrons) have a much smaller lifetime, of the order of microseconds in very pure water. ...