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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3answers
188 views

Why is 1,2,3,4,5,8-hexahydronaphthalene more stable than 1,4,4a,5,8,8a-hexahydronaphthalene? [closed]

Why is 1,2,3,4,5,8-hexahydronaphthalene (1) more stable than 1,4,4a,5,8,8a-hexahydronaphthalene (2)? A follow-up question is about stability being estimated by counting the α-hydrogens. In the first ...
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1answer
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Comparing stability of 2-propenyl cation and 1-propyl cation

Compare the stability of 2-propenyl cation and 1-propyl cation: $$\underset{\text{2-propenyl cation}}{\ce{CH2=CH-CH2+}}\qquad \underset{\text{1-propyl cation}}{\ce{CH3-CH2-CH2+}}$$ In 2-propenyl ...
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3answers
241 views

Stability of α-chlorocarbocations

I'm trying to compare the relative stability of two carbocations: $$\ce{CH3-\overset{+}{C}H-Cl}\quad\text{vs}\quad\ce{CH3-\overset{+}{C}H2}$$ Does the $\ce{Cl}$ exert a +M effect to stabilise the ...
2
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1answer
313 views

Comparing the stability of geminal diols [duplicate]

Arrange the given gemdiols in decreasing order of their stability: I thought that high angle strain would correspond to low stability, and therefore I compared the stability of the rings, which ...
2
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0answers
146 views

Why does more s-character stabilise Carbanions?

Since carbanions carry a negative charge, more the distribution of electron density, more is the stability. What does this have to do with more s character? Does the distribution of electron density ...
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2answers
121 views

Method of deriving some properties or possible method of synthesis of a specific monomer

This is kind of like two questions but since they're related I have put them together. Consider a monomer under a hopefully anatomically correct name 'Phenyl Carbolithia Divinylene Oxide [$\ce{...
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1answer
3k views

Relative stabilities of tropylium and cyclopropenyl carbocations

How can the stabilities of the tropylium and cyclopropenyl carbocations be compared? Both are aromatic according to Hückel's rule. I think that to compare the stabilities, we must either count the ...
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61 views

Adding a base and a salt to a hydrated complex

The question goes like this: $\ce{Fe(NO3)3}$ V= $\pu{1 liter}$ and $\ce{[Fe(NO3)3]} =\pu{0.1 moles/liter}$. Calculate the $\mathrm{pH}$ of this solution using the values of $K$ given. We add a solid ...
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1answer
86 views

More Anti-bonding or less bonding electrons?

Is a molecule more stable with less bonding electrons or more anti-bonding electrons? This question arose when I was asked the stability comparison between $\ce{N2^+}$ and $\ce{N2^-}$.
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207 views

Stability of carbocation

While comparing the stability, as the $\ce{CH3}$ group is electron donating, the first structure should be more stable due to this reason. But apparently the second one is more stable. Is there ...
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2answers
293 views

Rate of dehydration of alcohols having keto group

The following question was asked in IITJEE-Screening 2000, Which of the following will be most readily dehydrated in acidic conditions? I thought that the answer would simply be (c), as its ...
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1answer
285 views

Stability of carbocations with -M groups in beta position

First part The original question was to arrange the following compounds in the order of their rate of dehydration with conc. $\ce{H2SO4}$:- (A) $\ce{CH3-CH(OH)-CH2-CH=O}$ (B) $\ce{CH3-CH(OH)-CH2-C(=O)...
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2answers
535 views

Order of rate of acid catalysed dehydration of alcohols

The relative rate of acid catalysed dehydration of following alcohols would be: According to me, we have to arrange them in order of their carbocation stability. Q will be the most stable as it is ...
5
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1answer
179 views

Reaction of styrene oxide with hydrogen iodide

The question is to find the product of the reaction of Styrene Oxide with Hydrogen Iodide. According to me, this should be the mechanism- As the benzylic carbocation will be more stable, therefore ...
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0answers
79 views

Stability of free radicals [closed]

If given a question to compare stability of free radicals, can we always check it by same parameters that we use for stability of cations (since both are electron deficient) or is there any exception ...
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1answer
403 views

Comparing heat of hydrogenation among 1‐methylcycloprop‐1‐ene, 3‐methylcycloprop‐1‐ene and methylenecyclopropane

Problem Which of the following orders is correct for heat of hydrogenation of these compounds? A) 1 > 3 > 2 B) 3 > 2 > 1 C) 3 > 1 > 2 D) 2 > 1 > 3 Answer My Attempt Heat of ...
4
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1answer
311 views

Rate of dehydration for butan-2-ol and butane-2,3-diol

A question taken from a test series (Vibrant, India): Amongst butan-2-ol and butane-2,3-diol, which has higher rate of dehydration? The carbocation formed in butane-2,3-diol is more stable as it ...
2
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0answers
52 views

Reactivity comparison between benzaldehyde and acetaldehyde [duplicate]

One of my teacher says that $\ce{Ph-CHO}$ is more reactive than $\ce{CH3-CHO}$ in performing nucleophillic addition reaction because $\ce{—Ph}$ is planar and thus offers less steric hindrance as ...
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45 views

Stability of radicals

I recently came across a question about the stability of radicals and this option was given as correct. $\ce {F2C^.H}>\ce {C^.H3} $ And the solution was given that $\ce{FC^.H2}$ and $\ce{F2CH^.}$...
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1answer
206 views

Stability of dialkyl substituted alkenes

The stability order of alkyl substituted alkenes with respect to heat of hydrogenation was given as $$\ce{R_2C=CH2} > \ce{RHC=CHR}~(\textit{trans}) > \ce{RHC=CHR}~(\textit{cis}).$$ While I ...
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2answers
193 views

Thermal Decomposition of Sulfur Hexafluoride

What is the thermal decomposition temperature for $\ce{SF6}?$ I've heard it decomposes into $\ce{F2}$ and $\ce{SF4}$ only to decompose further into $\ce{S2}$ and $\ce{F2},$ but I haven't found much on ...
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3answers
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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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2answers
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Stability of F- Cl- Br- I-? In aqueous state [closed]

If we talk about hydrolysis F- will be more heavily hydrolysed so it should be more stable in aqueous state. But I know that HI is a stronger acid than HF. So the stability of conjugate acid ie I- ...
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1answer
60 views

Why are bonded ions more stable than separate ions? [closed]

I was reading on the Born-Haber cycle when I encountered a problem. The textbook seemed to suggest that since energy must be supplied to separate an ionic compound into it's composite ions, then the ...
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2answers
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Why exactly is a fluoride anion a stronger base than iodine anion?

First off, I've learnt that stronger acids produce weaker conjugate bases (through Brønsted–Lowry acid–base theory). Then I looked at the $\mathrm{p}K_\mathrm{a}$ values of $\ce{HF}$, $\ce{HCl}$, $\...
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2answers
934 views

I am confused about the stability of carbanion III and IV in the image

I am confused about the stability of carbanion III and IV in the image, I think III is more unstable because of electron donating effect (+R) of $\ce{-OCH3}$ group but my book says III is more stable ...
4
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1answer
846 views

Newman projections: how to tell which groups are bulkiest to determine what is the most stable conformation?

The scenario Let's say we have a molecule where in the Newman projection the front carbon has a hydrogen, methyl and an ethyl, and in the back carbon there's a hydrogen, something like a S, Cl or Br (...
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1answer
389 views

Stability of CI4 and PbI4

I have read in my textbook that $\ce{CI4}$ is more stable than $\ce{PbI4}$ due to inert pair effect. But shouldn't we also consider the effect of steric repulsions? In $\ce{CI4}$, four large iodine ...
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1answer
616 views

Reactivity and transport safety of substituted methyl benzoates

This was a practice question from an MCAT book whose answer I didn't really understand: The normal reactivity of methyl benzoate is affected by the presence of certain substituents. Which of the ...
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2answers
88 views

Ortho effect in cyclohexane

Compare the acidities and basicities of the compounds in the first and second row respectively. In aromatic compounds the methyl group would cause an "ortho" effect. Here we don't have an aromatic ...
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1answer
63 views

Energy lost due to stability [closed]

We used to say that when an atom is stable it is in its minimum energy state.Every shell has its fixed energy. So from where does the energy come which is lost by an atom to achieve stability. Do ...
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2answers
14k views

Why Cu+ is unstable in aqueous medium?

This was one of the question that was given in the school exam. But what I am expecting is that $\ce{Cu+}$ attains a $d^{10}$ configuration by losing one electron from s-subshell. Since it has fully ...
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0answers
33 views

Stability of Peroxynitric Acid in cold temperature

I have a question about the stability of Peroxynitric Acid i.e. $\ce{HO2NO2}$ at cold temperature. I know that it becomes stable when temperature decreases, but what is the specific reason for it? I ...
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0answers
166 views

Cis-Trans Isomers Heat of Combustion

Consider the 4 cis-trans isomers for the above compound. In what way would the cis-trans isomers affect their heat of combustion. I think that if the substituents are on alternating sides of the ...
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2answers
246 views

Why is hofmann product prefered here?

In the following reaction, Hofmann elimination is preferred. This reaction takes place by E1 mechanism. I thought the Zaitsev product would be major due to 1 extra hyperconjugating structure. In the ...
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5answers
14k views

Is the t-butyl carbocation more stable than the benzyl carbocation?

Various authors have different views regarding stability order of the benzyl and t-butyl carbocations. $$\ce{PhCH2+ ; (CH3)3C+}$$ In my opinion, resonance effect dominates, so the benzylic ...
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0answers
33 views

What explains the stability of aromatic compounds? [duplicate]

We are taught in High school that aromatic compounds are highly stable. Why is that true? Also, Why are Antiaromatic compounds highly unstable? Aromatic compounds have 4n+2 (n is a whole number) ...
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0answers
287 views

Stability order of p-quinone, o-quinone and diphenoquinone

Question Determine stability order: Answer Thoughts I found this question quite tricky and confusing. According to my concepts and logic 3 should be non-aromatic, while 1 and 2 are antiaromatic. ...
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2answers
255 views

Which resonance structure would be favorably contributed to the actual structure?

Total number of pairs of resonating structure in which second is more favorable than first: I know (d) and (e) have second structure more stable. (f) has both same. According me to, (a) and (c) ...
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1answer
818 views

Why is iron pentacarbonyl known, but iron(III) hexacarbonyl is not?

Why is the neutral complex $\ce{[Fe(CO)5]}$ known, but the cationic carbonyl complex $\ce{[Fe(CO)6]^3+}$ is not known?
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1answer
100 views

Para effects on substituents in aromatic compounds

I wanted to know how to compare the following compounds on basis of acidic strength. I have to find the acidic strength of following compounds with $\mathrm{X}=\ce{CH3, \ OCH3,}$ and $\ce{NO2}$. For ...
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0answers
392 views

Are all ions stable? [closed]

My science teacher says that all ions are stable, which seems wrong to me. For example $\ce{He^{-1}}$ is an unstable ion of helium, and although it might not exist in the real world, it is still ...
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1answer
158 views

Are all stable Xenes (graphene-like 2D honeycomb sheets) buckled?

background: Per this abstract Silicene, germanene and stanene are part of a monoelemental class of two-dimensional (2D) crystals termed 2D-Xenes (X = Si, Ge, Sn and so on) which, together with ...
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0answers
79 views

Why isn't protium nucleus considered most stable nucleus?

My chemistry teacher told me that $\ce{^{56}Fe}$ is the most stable nucleus because of the highest binding energy per nucleon. But if we consider a protium nucleus, it has only 1 proton so there is no ...
3
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1answer
753 views

Which is more stable chemically: DNA or peptide

Assuming enzyme-free environment, and the DNA and peptide are lyophillized, and then stored in vials under the same conditions (temperature and humidity). On average, which would be more chemically ...
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1answer
883 views

Why do stable compounds have a lower heat of combustion?

My brain somehow doesn't accept that more stable compounds require have less enthalpy. Isn't it like, if a compound is stable, it requires more energy to break the bonds because the compound doesn't ...
4
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1answer
4k 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 ...
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3answers
217 views

Odd looking carbocation stability order [duplicate]

I am studying introductory organic chemistry, suddenly this one started looking odd, The carbocation stability for three compounds as given by my book is shown below, Let me call those as ...
11
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1answer
141 views

The Evasive Ether: Existence of diethynyl ether?

I tried to find online whether the compound diethynyl ether, $\ce{HC#COC#CH}$, exists in a stable state at STP, mainly out of curiosity, but also because it would be interesting to study the ...
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1answer
2k views

Why is the chlorine ion more stable than the chlorine atom? [closed]

In heterolytic cleavage, for instance, $\ce{NaCl}$ breaks in two fragments $\ce{Na+}$ and $\ce{Cl-}$. If chlorine is fully filled because it takes one electron from sodium, then why does chlorine make ...

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