Jannis Andreska
  • Member for 7 years, 8 months
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1 answers
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Boron trihalides acidity
5 votes

The following order is experimentally found: $$\ce{BF3}<\ce{BCl3}<\ce{BBr3}<\ce{BI3}$$ This stands in contrast to what is expected when the electronegativity of the halides is considered. A ...

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2 answers
1 votes
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Identification of lithium and strontium salts
4 votes

If your solution contains only $\ce{Li+}$ or $\ce{Sr^2+}$, you can differentiate them by adding a sulfate solution (for example, $\ce{Na2SO4}$ or diluted sulfuric acid). If strontium is present, a ...

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2 answers
4 votes
354 views
How to identify an emerald green solution with possibly two anions?
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9 votes

You can have two different anions if your solution is a mixture of two different metal salts, a chloride and a sulfate. The color change from green to blue upon dilution with water fits well with $\ce{...

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5 votes
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2-methylpropene to tert-butyl alcohol Reaction Mechanism
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7 votes

It is an acid-catalyzed hydration of the double bond. First, the double bond is protonated to yield the tert-butyl cation which is most stabilized by hyperconjugation (protonation at C2 would form a ...

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2 answers
0 votes
345 views
How to calculate the concentrations of the species in the carbonate equilibrium from a titration with hydrochloric acid?
1 votes

You have correctly identified the amount of substance $\ce{HCl}$ which were necessary to neutralize all $\ce{HCO3-}$ and $\ce{CO3^2-}$ in the sample. With the given sample volume of $\pu{10 cm^3}$, we ...

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3 answers
9 votes
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Nitration of naphthalene and anthracene
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When you compare the stability of the carbocation intermediates of polycyclic aromatic compounds, you have to consider if the aromaticity of one of the rings is sacrificed in order to delocalize the ...

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1 answers
3 votes
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Identification of unknowns with varying solubilities and states of matter
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The solutions which you have already found look good so far. For solid A, we need to find a compound which thermally decomposes into $\ce{N2}$ and an element which is only soluble in oxidizing acids ...

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1 answers
4 votes
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Dehydration of secondary alcohol via E1 mechanism
2 votes

Your proposed mechanism looks reasonable. I think that acetic acid primarily serves as an acidic solvent for the reaction. However, in the presence of concentrated sulfuric acid, $\ce{CH3CO2H}$ can be ...

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1 answers
7 votes
8k views
Convert benzene to isopropylbenzene
5 votes

You are right, both abstracting $\ce{Cl-}$ from the alkyl chloride with Lewis acid as well as dehydration of isopropanol with $\ce{H2SO4}$ are suitable ways to generate the 2-propyl carbocation, your ...

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1 answers
2 votes
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Reactions of tin (IV) iodide with potassium iodide and water
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If iodide is oxidized to iodine (the cause of the yellow color), then something needs to be reduced in turn. Potassium is already in its most stable oxidation state (+I), so tin will be reduced, from $...

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6 votes
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What is the purpose of ammonium chloride in anti hydrogenation of alkynes?
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Products from reaction step (1) are the trans-alkene and 2 equivalents of the amide $\ce{LiNHEt}$, a strong base. Step (2) is the workup of the reaction mixture with aqueous $\ce{NH4Cl}$ solution, ...

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3 answers
11 votes
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Where is the acid in DNA/RNA?
10 votes

The phosphate ester groups which connect the nucleotides contain one acidic proton at their OH group, and two at the end of each strand. As you can see here, here and in the picture below (with the ...

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2 answers
17 votes
5k views
Reaction of perchloric acid with cyclopropenol
7 votes

The first step is indeed 1,2-addition of the Grignard reagent to the keto group, and product A is the alcohol: Treatment of the alcohol with the strong acid $\ce{HClO4}$ cannot yield the usual ...

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3 answers
1 votes
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Resonance stabilized carbanion
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2 votes

(b) does not show resonance because the second resonance structure (with negative charge at oxygen and double bond in the ring) violates Bredt's rule. The carbon $\ce{sp^3}$ orbital with the negative ...

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1 answers
1 votes
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Determine standard enthalpy of formation of salt given other reactions
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The standard enthalpy of formation $\Delta H_\mathrm f$ refers to the formation of 1 mole of product, with the educts and product being in their respective standard states. The fourth equation is ...

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2 answers
2 votes
9k views
Oxygen production from thermal decomposition of metal oxides
4 votes

A lot of metal oxides decompose under liberation of $\ce{O2}$ when subjected to sufficiently high temperatures. For example, $\ce{HgO}$ decomposes at temperatures above $\pu{500^\circ C}$ into ...

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3 answers
4 votes
7k views
Could someone please explain the difference between m/z and m/e in mass spectroscopy
3 votes

$m$ is the atomic mass of the ion (in units ($u$); $1u=1.665402\times10^{-27} \mathrm{kg}$), $z$ is the number of its positive/negative charges. $z$ should not be used in interchange with $e$ because ...

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3 votes
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Meaning of "mono-N-demethylation"
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Mono-N-demethylation means the removal of a single (mono) methyl group from a nitrogen(N)-containing functional group. For example, a reaction which transforms the alkylated amine group $\ce{-NHCH3}$ ...

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2 answers
10 votes
12k views
Mercury assisted deprotection of dithiane
12 votes

$\ce{Hg^2+}$ has a high affintity to thiols and other sulfur functional groups, and therefore $\ce{HgCl2}$ forms a Lewis acid-base adduct with the dithiane. The cyclic sulfonium cation undergoes ring ...

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1 answers
0 votes
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Explaining Ba(OH)2 as a base?
2 votes

Barium hydroxide – or more exactly, the hydroxide ion – is a Brønsted-Lowry base, because in aqueous solution, it is completely dissociated into $\ce{Ba^2+}$ and $\ce{OH-}$ ions: $$\ce{Ba(OH)2 -> ...

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2 votes
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How would one compare the magnitude of covalent character between SnCl4 and SnF2 using Fajan's Rules?
1 votes

Fajan's rules for the prediction of bond character can be summarized in two points: Large cation with low positive charge + small anion $\rightarrow$ ionic Small cation with high positive charge + ...

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6 votes
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Semipinacol-type rearrangement leading to ring expansion
7 votes

Three-membered rings are not exceptionally stable, on the contrary, they suffer a lot of ring strain and readily take part in ring-opening reactions. Exceptions include the Hückel-aromatic ...

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5 votes
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Protonation of a compound having alcohol and ethereal linkage
4 votes

The alcohol group of your educt (tetrahydrofurfuryl alcohol) is protonated, and after subsequent loss of water, the resulting primary carbocation can rearrange to a more stable 6-membered ring cation, ...

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1 answers
2 votes
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Does precipitated copper carbonate contain impurities
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2 votes

Yes, the water contained in the freshly filtered precipitate will contain dissolved $\ce{Na2SO4}$, as the latter is the soluble by-product of your double displacement reaction. To get rid of it, you ...

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1 answers
6 votes
694 views
Can you synthesize phenol from salicyladehyde?
5 votes

It is possible to convert salicylaldehyde into phenol in a two-step process. Firstly, salicylaldehyde is oxidized to salicylic acid with a standard reagent like $\ce{KMnO4}$ (see the answers to this ...

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3 votes
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Does Methyl Iodide (CH3I) react with water (H2O) and if it does what would be its byproducts?
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2 votes

Methyl iodide is hydrolyzed by water in an $\ce{S_{N}2}$ reaction ($\ce{S_{N}1}$ is disfavored by the instability of the primary methyl cation), which yields methanol and hydroiodic acid as products. ...

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1 votes
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What is the oxidation state of C in this lewis structure?
2 votes

When determining the oxidation state of carbon in the given compound (formic acid), the electronegativities of the atoms directly bonded to the carbon are taken into account, because, as already ...

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4 votes
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What is the correct Lewis structure of diazomethane?
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The image above depicts three mesomeric structures of diazomethane ($\ce{CH2N2}$). When you count the valence electrons for every atom, you will find that only the left and middle structure satisfy ...

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Manganese(VII) oxidation state
2 votes

The fact that manganese has a stable oxidation state in which it has (formally) lost all its $d$ electrons does not mean that it cannot be considered a transition metal, because it still has a lot of ...

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7 votes
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Why does phosphoric acid mask the colour of iron(III) complex in water?
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11 votes

When phosphoric acid is added to an aqueous solution of iron (III), the ligands in the yellow complexes $\ce{[Fe(OH)(H2O)5]^2+}$ and $\ce{[Fe(OH)2(H2O)4]+}$ ( $\ce{[Fe(H2O)6]^3+}$ are weakly colored ...

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