Questions tagged [stability]

Applied to a chemical species, the term expresses a thermodynamic property in reference to a standard, stating that one state is lower in energy than another. The tag should be applied to questions seeking answers with respect to the stability (or instability) of a certain chemical species, molecular entity and/or electronic structure. It must not be applied to questions about the reactivity of particular chemical species.

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17
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4answers
54k views

Why is formic acid a stronger acid than acetic acid?

I am told that because the methyl group is electron donating in the conjugate base of acetic acid, this destabilizes the conjugate base by exacerbating the existing negative formal charge on the ...
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0answers
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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 $\...
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2answers
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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 ...
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1answer
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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 ...
7
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2answers
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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 ...
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1answer
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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
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1answer
199 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 ...
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1answer
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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.
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1answer
74 views

Is there a possible effect of 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 ...
8
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1answer
2k 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 ...
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1answer
239 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 ...
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1answer
369 views

Major form of methyl 3-hydroxy pent-2-enoate?

I came across this question in a test: The enol form is the ________ form for 3-hydroxy pent-2-enoate? (major/minor) My argument is that the enol form must be more stable because of hydrogen ...
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2answers
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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. ...
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2answers
365 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 ...
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6answers
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How to determine the most stable carbanion?

Which of the following carbanions is the most stable? I think the answer is either a or c, as in d there are no chances for the carbanion to have its charge become less. In b I think there is a ...
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2answers
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Stability of transition metals in aqueous solution

Which is more stable in aqueous solution: $\ce{Cr^3+}$ or $\ce{Mn^3+}$? Why? My approach: $\ce{Cr^{3+}}$ should be more stable as the $\ce{3d}$ electrons will enter the $\mathrm{t_{2g}}$ orbitals. ...
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1answer
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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, tertiary/...
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1answer
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Energy required to break the “delocalised electron cloud” of benzene

I learned that when benzene undergoes hydrogenation, $\pu{208KJ}$ of energy is given off and thus $\pu{152KJ}$ less energy than what would be given off if Kekule's structure was correct. My confusion ...
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1answer
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What is the difference between the roles of a surfactant and a stabilizer in the process of nanocrystal growth?

The crystals that I am synthesizing use two different stabilizers CTAB and SDS, but they say one is used as a surfactant and since they are both stabilizers what is the need for both?
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2answers
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Delocalised electrons and stability of benzene

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 ...
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1answer
980 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+} + ...
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1answer
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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?
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1answer
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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 ...
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3answers
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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 one....
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2answers
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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 ...
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3answers
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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 chose C as the correct answer but, in the answer key it is given to be B. C is the ...
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5answers
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Oxygen or carbon with a positive charge? (comparison of canonical structures)

Which of the contributing structures of the resonance 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 unanimously ...
10
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1answer
765 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, it ...
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2answers
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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 ...
2
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3answers
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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 $\ce{R2}$ can be an organic substituents or ...
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3answers
957 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
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1answer
996 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 ...
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1answer
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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 ...
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1answer
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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 ...
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2answers
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How do the molecules know the future? How do they proceed to form “Most Stable” compound?

I'm tutoring few students for Chemistry. During the course, I many times use the phrase "Out of these possibilities this one is stable. So it is formed". I get questions like, "How do the molecules ...
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5answers
116k 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?
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2answers
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Why do sulfur and oxygen form sulfur dioxide?

Both sulfur and oxygen have 6 electrons in their outermost shell. Since both only need two electrons to stabilize, why doesn't just one atom of oxygen react with one sulfur atom, forming sulfur ...
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1answer
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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 ...
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2answers
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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.
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1answer
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Why are noble gases stable? [duplicate]

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 ...
5
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1answer
242 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 $\ce{TeO4^{-2}}$, Selenate $\ce{SeO4^{-2}}$ and Sulfate $\ce{SO4^{-2}}$ - ...
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1answer
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Why is a 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 ...
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1answer
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What is the order of stability of the resonance structures of furan?

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?
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1answer
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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. ...
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3answers
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What makes an epoxide stable?

Overall ring strain seems to be a big issue when it comes to organic chemistry. That is why cyclopentane may be in an "envelope form" or why cyclobutane may be in a kinked, kite form. Both of these ...

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