Questions tagged [physical-organic-chemistry]

For questions about how organic molecules and reactions are investigated using physical experiments.

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Calculating the Barrier Between Rotamers

There are two stable conformations of a medium-sized organic molecule roughly 5 kcal/mol apart in ground state energies. One is probably the global minimum conformer identified through a conformer ...
quantchem's user avatar
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What is this gel byproduct of acetylsalicylic acid recrystallization?

I did a very simple acetylsalicylic acid synthesis from salicylic acid and acetic anhydride (with phosphoric acid as a catalyst). After rinsing, filtering and drying the product I dissolved it in ...
Thomas's user avatar
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Electrolysis of benzyl alcohol in methanol

I am conducting following electrochemical experiment on Au wires in organic medium: I suppose the anodic reaction goes through a benzaldehyde intermediate: The cathodic reaction is hydrogen ...
Mäßige's user avatar
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Cation/Anion UV-Vis absorption

I want to understand how the ground state absorption of a molecule shifts if an electron is added or removed. I found these two publications 1 and 2 that observe shifts, but both times a redshift, be ...
Martin 's user avatar
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Energy Decomposition Analysis for SN2 involving ambident nucleophiles and an alkali metal counterion

I am wanting to perform an EDA on transition state structure of the nucleophilic attack of an ambident nucleophile (2 atoms that could be used in nucleophilic attack on the same molecule) on a benzyl ...
MrAmateurChem's user avatar
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How can we prevent retrogradation of starch?

Are there any additives which can prevent retrogradation of starch? I have prepared 13% of starch solution along with 2% of NaCl. The results were bit better. The synthesized gel was flowable with ...
Aqib Mehmood's user avatar
1 vote
1 answer
223 views

Band structure of solids in general

As my last question (Semiconductors and their electronic bands) was badly structured, I decided to elaborate my questions a bit. As I now know, every solid/liquid forms a band structure, so all ...
Mäßige's user avatar
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Why is cyclohexane more polarizable than benzene?

Looking at figure 4.2 here, we can see experimentaly that cyclohexane is more polarizable than benzene. Why is this the case? Intuitively, I would think that because the orbitals in benzene are more ...
McKinley's user avatar
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Can species with diffrent number of electrons be isoelectronic?

According to IUPAC gold book- Does this meam that 2 species with diffrent electron number, but same valence electrons, be considered isoelectronic Say a molecule XY and ZY where X and Z belong to the ...
ThatApollo777's user avatar
4 votes
1 answer
152 views

What is the probability the bonds broken with sunlight reforming back?

The maximum wavelength $\lambda$ capable of breaking a chemical bond can be estimated as $\lambda = hc/E.$ UV-A $(\pu{380 nm})$ can break bonds with the energy up to $\pu{315 kJ mol^-1},$ UV-B $(\pu{...
Neal Conroy's user avatar
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Reaction Order from Percent Yield?

Referencing this paper, I am trying to approximate the order of reaction for cyclohexane (4a). Trials 1-3 provide the relevant information of mmol changes and corresponding percent yield but I'm ...
Boris Tangerine's user avatar
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If Qc> Kc how can forward reaction can take place

If Qc>Kc then there will be a net backward reaction but still forward reaction will take place. My problem is if Qc>Kc forward reaction will become non spontaneous right. So how can that happen, ...
Zayden's user avatar
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Is there a quantitative definition of inductive effect?

Usually, Inductive effects are compared using the electronegativities and distances. However, this only works in compounds with similar structures. For example, we can predict the following orders of ...
ananta's user avatar
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3 votes
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Boiling points of hydro- and fluoro-carbons

I am teaching organic chemistry to a high school student. While discussing Teflon, we referred to the corresponding section in the 10$^\text{th}$ edition of "Organic Chemistry" by Solomons ...
ananta's user avatar
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Why is the dipole moment of Anisole less than that of Phenol? [closed]

According to Wikidata, anisole has a dipole moment of 1.38D and according to this page on Researchgate, phenol has a dipole moment of 1.70D. Resonance in anisole: Resonance in phenol: According to my ...
Solus's user avatar
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The edge case of an edge case: Vapor emissions of the descaling agent Sulfamic acid

I am wondering about the following scenario: What happens if ready bought sulfamic acid descaling (usually 15% cont. + $\ce{H2O}$) is vaporized or at least steam develops while very briefly descaling ...
Inaudio's user avatar
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Does a free radical localized at one atom in a compound make sense or could it be?

In most of our cases, a dot that represents a radical is always considered affiliated to an atom in a molecule, especially when we talk about a reaction mechanism. However, Levine's Quantum Chemistry [...
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If Ethyne has the lowest C-H bond length (highest C-H bond energy) compared to Ethane and Ethene, why is it the most acidic? [duplicate]

I am not an expert in chemistry, but these are the few facts I know from Standard XII chemistry books (these facts could be wrong or incomplete or modified by now). Facts I know - Ethane has 'sp$^3$' ...
Souparna Nath's user avatar
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Better Way for Crushing Coconut into 500 mesh Coal for Carbonization

I am planning to use coconut as a raw material for carbonization, but I need to crush it into 500 mesh coal. Currently, I am using a mortar and pestle to grind the coconut shell into a fine powder, ...
Becker Hija's user avatar
2 votes
1 answer
235 views

Finding concentration of ascorbic acid

Question: A person applied following procedure for the determination of ascorbic acid (Vitamin C) in a sample solution. A volume of 20.00 cm3 of the ascorbic acid sample was reacted with 25.00 cm3 of ...
Jane902's user avatar
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Find percentage of carbon monoxide reacted using ideal gas equation

Question A palladium or platinum catalyst was used in an automobile to convert carbon monoxide gas to carbon dioxide according to the following reaction: $$\ce{2CO(g) + O2(g) -> 2CO2(g)}$$ A ...
Jane902's user avatar
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2 answers
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Apparent circularity of the definition of mass [closed]

I am not a chemistry student, so forgive me for the naïvety of the question. The atomic mass of an atom is defined relatively to the mass of 1/12 of the mass of an unbound neutral atom of carbon 12 in ...
Oliver Goldstein's user avatar
-2 votes
1 answer
196 views

Confusion regarding what reduction/oxidation means in reactions having covalent compounds [closed]

In the formation of NaCl, Na gets oxidised because it loses an electron, while Cl gets reduced because it gains an electron. But how does this concept work in the case of covalent compounds, ...
Pumpkin_Star's user avatar
2 votes
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How do salts affect pH? [closed]

Since pH measures the effective proton concentration, it is the concentration of a very specific type of cation. I know if salt reacts with water, it will affect pH. But my question is, how does the ...
Ignoramus's user avatar
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2 answers
436 views

What will be the product of 1 eqv Benzene reacts with 1eqv H2? [closed]

how equivalent concept is applied in the above problem, Kindly help me out with the answer and proper explanation. As, I am getting confused in mole concept and equivalent concept here.
Amritendu Biswas's user avatar
1 vote
0 answers
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What happens to polymers under high pressure?

What happens when you have polymers under high pressure? My very sketchy thoughts of polymers are that they can be thought of tangles of carbon chains surrounded by hydrogen, but that some polymers ...
UVphoton's user avatar
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Why doesn't tetrachloromethane react with aqueous sodium hydroxide under reflux?

$\ce{CCl4}$ does not react with hydroxide nucleophile whereas $\ce{CH3Cl}$ does. I had initially thought that it was due to symmetrical geometry of $\ce{CCl4}$ and so the dipoles cancel out and the ...
Ashiq Ibrahim's user avatar
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Why we use various layers in OLED (ETL,EIL,HTL,HIL)? How they increase efficiency OLED device? [closed]

Currently, I am studying the working of OLED devices! The device can work with just three layers which are Anode, Cathode and Emission layers. I know the fact that the work function is an important ...
Gaurav Lokhande's user avatar
-2 votes
1 answer
189 views

Boiling and melting points of hydrocarbons [closed]

What happens while boiling and melting hydrocarbons? Which bonds are broken? When we compare the boiling point (b.p.) and melting point (m.p.) of certain hydrocarbons the order is inverted. For ...
Ujjawal Mishra's user avatar
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1 answer
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Fluorine detection in organic compounds

Many of you will know why I am asking this question. There is a lot of attention recently to the dangers of the so called Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS). In essence organic ...
Boris Hamanov's user avatar
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1 answer
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Why do we need Equilibrium Constant as well as Acid Disocciation Constant? [closed]

I did the experiment to find out the dissociation constant of a weak acid using Henderson equation. However, after going through the theoretical part of the experiment, I am wondering why we need two ...
Sanu_012's user avatar
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-1 votes
1 answer
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Why in calculating 25 mM of Tris HCl the answer in gram is automatically refer to the gram in 1000 ml [closed]

In the lab class,my teacher told me that the answer i get in grams is automatically the grams in 1000 ml. Why is it possible without we doing anything the grams i get automatically the grams in 1000 ...
Arpaphat A's user avatar
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1 answer
155 views

How does addition of side chains affect solubility and processibility of polyphenylene vinylene?

I am studying electrical engineering and physics. In a recent lecture I was told the $\ce{OC1C10}\text{-PPV}$ molecule has the chains added to the oxygen atom down below because it allows for ...
ubuntu_noob's user avatar
3 votes
1 answer
229 views

Comparing rates of substitution reactions

The following question was asked in an exam I gave recently Compare the overall rates of the following substitution reactions $$\ce{CH3Cl ->[OH-][Weak P.A.S] CH3OH}$$ $$\ce{CH3CH2Cl ->[OH-][ ...
Adithya's user avatar
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2 votes
0 answers
240 views

Why is the enthalpy of formation of 2,2-dimethylpentane larger than that of 2,2,3-trimethylbutane?

Firstly, it is commonly known and taught that branched alkanes are more stable than linear ones, and so have larger enthalpies of formation. But why is that the case? Are there some steric ...
Vorld's user avatar
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8 votes
1 answer
232 views

Out of tropolone and tropone, which is more soluble in water?

According to me tropolone has intramolecular H-bonding, so extent of H-bonding with water will decrease and thus, will be less soluble. Tropone (Cyclohepta-2,4,6-trien-1-one): Tropolone (2-...
ProBro's user avatar
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1 vote
0 answers
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How do electrostatic effects effect facial selectivity in addition to cyclic oxo-carbeniums?

I was reviewing Dave Evans' notes for stereochemistry of C=X electrophile additions, and found this slide detailing differences in additions to cyclic oxo-carbenium electrophiles, but I don't ...
McKinley's user avatar
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0 answers
285 views

Why does Red Phosphorus react so violently with an oxidizer like Potassium Chlorate?

In Armstrong's Mixture, mixing those two chemicals results in a friction sensitive explosive which produces a loud bang. According to wikipedia, it is made by adding a strong oxidizer to red ...
jamieoliverswag's user avatar
2 votes
0 answers
55 views

What kinetic model does the hydrogenation reaction of dibenzyltoluene follow?

So during the course of my research, I've read countless papers related to the hydrogenation of dibenzyltoluenen and the dehydrogenation of perhydro-dibenzyltoluene. Now what I've noticed, is the fact ...
Bram's user avatar
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4 votes
0 answers
36 views

Normalising Kinetic Isotope Effect Per Deuterium Atom

I've synthesised a protic and deuterated version of a specific molecule where there are two deuterium atoms in the latter. I then go about and measure the kinetic isotope effect (KIE) for a reaction ...
Hazinga's user avatar
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2 votes
1 answer
165 views

Small scale gas-to-liquids via Fischer–Tropsch — is it even possible?

I'm really interested in the Fischer–Tropsch gas-to-liquids (GTL) process. A lot of people are using wood or other biomass feedstock to make syngas on small scales (farms, shops, etc.). Practically, ...
Starbright's user avatar
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0 answers
141 views

pKa of acetic acid in pure NH3?

Acetic acid completely dissociates in liquid ammonia and I would like to know the $\mathrm{p}K_\mathrm{a}$ value for the acid in that solvent. Can anybody point me to a reference?
ScepticalChymist's user avatar
2 votes
0 answers
723 views

Comparison of boiling points of para-derivatives of phenol

The boiling points of four para-derivatives of phenol are: How can we compare the boiling points of p-nitrophenol and p-aminophenol? Apart from the hydroxyl group, p-nitrophenol has two oxygen atoms ...
Apurvium's user avatar
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3 votes
3 answers
924 views

salt hydrolysis and pH calculations

I am a high school student and I am very confused in salt hydrolysis My confusion is that: when we talk of hydrolysis of salt of weak base and weak acid, we internally assume the degree of hydrolysis ...
Arun Bhardwaj's user avatar
2 votes
0 answers
68 views

Origin of the NMR shielding

In a paramgnetic material the induced dipole moment of atoms or (molecules) of the material aligns with the external field. I can understand this by Zeeman splitting. A term symbol splits into states ...
Anton's user avatar
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7 votes
1 answer
4k views

Aspirin Hydrolysis at pH 2

Conducting an experiment, I found that very little salicylic acid was evolved performing hydrolysis at $\mathrm{pH \ 2}$ and at $\pu{45 ^\circ C}$. In fact, far more salicylic acid was evolved at $\...
Mas's user avatar
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1 vote
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Would the initial step of this mechanism be exothermic or endothermic? (Protonation)

My understanding is that since an O-H bond is being formed, the protonation step must be exothermic because energy is released upon bond formation. However, if I were to draw an energy/reaction ...
Beowulf8991's user avatar
3 votes
1 answer
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Why is the boiling point of sugarcane juice lower than the boiling point of water?

As the boiling point is a colligative property, one would expect that the boiling point of sugarcane juice should be higher than pure water because Sugarcane juice contains water (75–85%), non-...
Adarsh Payyavula's user avatar
5 votes
0 answers
150 views

Does π values vary in Hansch-Fujita equations for a given substituent?

I was reading about Hansch-Fujita equations from Hansch-Fujita paramaters and observed that the $π$ values of substituents (analogous to Hammet $σ$ values) change according to the specific environment ...
Anton's user avatar
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3 votes
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Can cycloaddition reactions be antarafacial?

Cycloaddition reactions of the form [4+2] and [2+2] are always suprafacial, as the geometry is too constrained to allow for antarafacial interaction between the FMO's. However, for cycloaddition of ...
Aniruddha Deb's user avatar