Greg E.
  • Member for 9 years, 7 months
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Are there any amphoteric substances other than water and ammonia?
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11 votes

First, it may be worth elucidating the nomenclature a bit and distinguishing between amphiprotic and amphoteric substances. The former are those that can react as either acids or bases in the ...

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Law of Multiple Proportions: What is the significance of small whole numbers?
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10 votes

There's no universally accepted hard cut-off, as far as I'm aware, which determines the range of numbers that would constitute "small" mass ratios. Generally, all textbook examples select compounds ...

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Does unsubstituted benzoic acid not show resonance due to steric effects?
9 votes

I have never heard of this effect occurring with an ordinary, unsubstituted benzoic acid. There is, however, a phenomenon known as the ortho effect that occurs when bulky groups occupy the ortho ...

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Rate of electrophilic bromination of toluene and ethylbenzene
3 votes

First, I think it's probably important to note that the difference in $\text{+I}$ effect of a methyl vs. ethyl is very small. In principle, the ethyl is more electron-rich, however the strength of the ...

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Determining exponents in a rate law with different data
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3 votes

If you've correctly determined exponent $m$, then to ascertain $n$ you can proceed by first dividing rate equation $(3)$ by rate equation $(2)$ (note that the rate constant $k$ cancels immediately and ...

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What is the nature of water?
7 votes

$\ce{H2O}$ is a both a neutral molecule and an amphoteric molecule — the two are not mutually exclusive terms. An amphoteric molecule is simply one that can act as either an acid or a base, ...

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Why is magic acid a superacid?
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21 votes

The explanation is that sufficiently strong Lewis acids like $\ce{SbF5}$ will form adducts even with very weak, traditionally non-coordinating Lewis bases like $\ce{SO3F-}$. The resulting anionic ...

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The acidity of boric acid
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16 votes

I think your suppositions and observations are basically correct. On the basis of general principles, it is certainly possible to imagine that such a mechanism might be at play. If one considers the ...

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Why does water favour nucleophilic substitution over elimination?
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10 votes

The nature of the substrate (in particular the degree of substitution of the α-carbon) is of principal importance in determining which mechanism predominates. Generally, $\mathrm{S_N1}$ and $\mathrm{...

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Reaction mechanism for oxidation of primary alcohol to carboxylic acid
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7 votes

A dichromate salt and aqueous sulfuric acid are used to prepare chromic acid in situ, which is among the most powerful oxidizing agents commonly available. A primary alcohol is first oxidized to an ...

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Why is cyclopentyne unstable?
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11 votes

Stable alkynes are normally linear, that is, they have bond bond angles of 180°. That is necessitated by the fact that alkynes are formed by two π-bonds and one σ-bond, which must be mutually ...

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Comparing acidities of substituted and aromatic carboxylic acids
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19 votes

In the case of 3-chloropropanoic acid vs. formic acid, I suspect the disparity in expected acidity can mostly be explained by solvation effects. The 3-chloropropanoic acid is much bulkier than formic ...

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Is sulfuric acid or hydrochloric acid stronger?
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11 votes

When using $\mathrm{p}K_\mathrm{a}$, one typically does not consider multiple dissociations for polyprotic acids, as the acidity of the conjugate base ($\ce{HSO4-}$ in the case of sulfuric acid) can ...

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What does lowercase r-s notation mean?
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13 votes

This notation is used to designate so-called "pseudoasymmetric carbons." This occurs in instances in which precisely two of the groups bonded to a tetrahedral carbon are structurally indistinguishable ...

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The reasoning behind predominance diagrams
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3 votes

I think you might be making a fundamental mistake when you differentiate between the "current amount of protons" and the "amount at equilibrium." All dissociation constants are based on equilibrium ...

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Would dissolving a salt and letting it sit for 48 hours have an effect on the solution?
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7 votes

The only reactions that I would expect to occur to any significant extent with pure water are acid-base reactions between the citrate and water, where water, being amphiprotic, could act as either an ...

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Can ketones next to a nitrogen hetero atom tautomerise?
2 votes

With a nitrogen adjacent to a carbonyl moiety, the functional group is an amide, and the tautomer involving a $\ce{C=N}$ bond is called an imidic acid. The amide is usually vastly more stable and ...

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How to calculate the pH of a buffer after HCl was added?
7 votes

For (a), the Henderson-Hasselbalch equation, $$\ce{pH} = \mathrm{p}K_a + \log([\ce{A^{-}}]/[\ce{HA}]),$$ comes in handy. Because your molarities and volumes of the acid and its conjugate base are ...

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Sodium cyanoborohydride and iminium reductions
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2 votes

I believe the reaction effected in the third step is a reductive amination. In this case, the ketone and amine moieties are both present within the same molecule, so the reaction proceeds ...

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Does solubility matter when measuring density with displacement method?
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3 votes

Volume is not a conserved extensive property of mixtures in the same way that other quantities like mass, net electric charge, number of particles, etc. are (within closed systems). That is to say, in ...

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What is the exothermic reaction of superglue with cardboard?
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10 votes

I believe this is due to the fact that cyanoacrylates polymerize by anionic (or sufficiently strong neutral nucleophile) addition. In particular, they react with hydroxyl ($\ce{-OH}$) groups; paper, ...

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Boat conformation: axial hydrogens
6 votes

If you want to be very precise (perhaps pedantic), then I would conclude that the question itself is a little dubious without additional clarification. Consider the IUPAC recommendation on Basic ...

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Designing a theoretical synthesis of methamphetamine from phenylpropyne
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16 votes

I think the synthetic route you've proposed is quite good for the most part. However, I think your use of $\ce{NaH}$ to remove the tosylate is incorrect. $\ce{NaH}$ is a very strong base, but not a ...

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Does knowing the ratio of masses of the elements in a compound lead to the unique chemical identity of the compound?
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16 votes

No, knowing the mass ratios is not sufficient by itself. In the absence of additional information (for example, molar mass) that would only be enough information to determine the empirical formula, ...

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Bromination Pathways with alkane, alkene, and alkyne substrates
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5 votes

I wanted to offer some commentary on the points you've enumerated: You mentioned halogenation of alkenes in the presence of $\ce{H2O}$. This reaction is known as halohydrin formation. It's worth ...

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Reaction Pathways - Substitution and elimination
4 votes

In theory, one can substitute a leaving group with retention of stereochemistry by performing two successive $\mathrm{S_N2}$ reactions. The first one inverts stereochemistry, and the second one ...

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What is C2H5-O-CH=CH2?
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9 votes

The particular reaction is of acetylene ($\ce{C2H2}$) and ethanol ($\ce{C2H5OH}$) to yield ethyl vinyl ether (IUPAC name ethoxyethene). It's one example of Reppe chemistry, a fairly diverse set of ...

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What are the priorities for substituent groups on a cyclohexane?
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4 votes

If the numerical sequence of locants is equivalent, the numbering should be assigned to correspond with alphabetical order. Hence, in your example, correct would be 1-ethyl-2-methylcyclohexane. ...

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Nitration of Aromatic Compounds
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5 votes

It's not advisable to consider these types of reaction schemes in a slavishly literal fashion. In reality, there are multiple proton transfer equilibria occurring simultaneously, and the reactions ...

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UV-VIS spectra of n-decanes
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3 votes

To the best of my knowledge, ordinary alkanes do not typically absorb anywhere in the UV/Vis region. The organic molecules that do typically contain electrons in $\pi$- or non-bonding orbitals, which ...

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