Questions tagged [physical-organic-chemistry]
For questions about how organic molecules and reactions are investigated using physical experiments.
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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 ...
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0
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37
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Would it be possible to separate and identify plastic compounds/mixtures?
In the lab I have been trying to identify and quantify the ratios of different components of sampled plastic compounds.
The ingredients are generally known:
Polymer matrix (PE or PP)
Pigments (...
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1
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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 ...
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0
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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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0
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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$^3$' ...
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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, ...
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2
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1
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41
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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 ...
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2
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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 ...
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2
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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 ...
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1
answer
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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, ...
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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 ...
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2
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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.
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Multiplicity of a transition state undergoing a six electron movement
How to specify the multiplicity for the transition state of a molecule undergoing a Cope rearrangement? I've read that one could technically approximate the transition state (TS) as a diradical, but ...
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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 ...
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0
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How significant is the effect of pi stacking on substituent bond dissociation in an enzyme?
Let there be a system of phenylalanine in a T-shaped pi-stacking configuration with a tyrosine. Both are part of a longer peptide (~40 amino acid separation in the chain).
In this system, an oxonium-&...
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1
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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 ...
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0
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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 ...
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1
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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 ...
6
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1
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536
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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 ...
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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 ...
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1
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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 ...
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1
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93
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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 ...
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1
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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-][ ...
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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 ...
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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-...
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0
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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 ...
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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 ...
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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 ...
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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 ...
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2
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1
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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, ...
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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?
2
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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 ...
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3
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3
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532
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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 ...
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0
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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 ...
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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 $\...
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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 ...
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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-...
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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 ...
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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 ...
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How do bonds rotate in pericyclic reactions?
In Pericyclic reactions, it is shown that the terminal bonds rotate (conrotation or disrotation) to allow for allignment of the FMO's, thereby forming the sigma bond
However, a detail that most of my ...
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What's the least common element in the universe? [closed]
What's the least common element in the universe? And what is its frequency measured in Hertz?
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Organic-catalysis microwaves [closed]
When we perform a organic reaction without any addtional catalyst except that the reaction is carried out under microwave condition we can accelerate this reaction in comparison with one under heating ...
2
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1
answer
53
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Carboxyllic acid Test
I'm currently in high school doing a project in chemistry. So I had to make a project where concepts from physical chemistry will be used alongside organic chemistry.
After going through my book I ...
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Will a salt dissociate completely in water to give free ions?
I was reading salt hydrolysis of a salt made from strong acid and weak base. I came across the hydrolysis of $\ce{NH_4Cl}$. These reactions were mentioned
$$\ce{NH_4Cl + H_2O<=>NH_3 + HCl \tag{...
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2
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Fermentation of glucose
I have trouble understanding as to what the last part of the increase in liquid level means. I believe this is the foam formed after the fermentation? I am calculating for the pressure but I have ...
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0
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What is the influence of citrate on PEG-modified polyacrylamide hydrogels?
I've been having a puzzle explaining the experimental results with the citrate anions and PEG modified polyacrylamide:
According to the experimental data there is a hydrogel swelling whenever citrate ...
3
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1
answer
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Vapors of Aqueous solutions
I'm dealing with a common photoresist developer TMAH (tetramethylammonium hydroxide) and attempting to design a vapor sensor for a sealed chamber. Now I havent been able to confirm what exactly is ...
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Primary kinetic isotope effect
Why does the transition state in both protonated and deuterated molecules have the same energy? My textbook assumes that during transitional state the isotopic bond is half-broken or on its way to ...
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1
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Overlap integrals in Hückel theory
In Hückel theory we are only interested in π systems, where $\mathrm p_z$ orbitals overlap. One of the approximations in Hückel theory is that the overlapping $\mathrm p_z$ orbitals are orthonormal:
$...
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How do we obtain the π molecular orbitals for allene via Hückel theory?
For a conjugated system, for instance 1,3-butadiene, we can try to obtain the π molecular orbital energies and wavefunctions via Hückel theory. In our given molecule, there are 4 interacting Pz ...
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