Questions tagged [physical-chemistry]
The study of chemical systems using the laws and concepts of physics. This usually requires the techniques of thermodynamics, statistical mechanics and quantum mechanics.
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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 ...
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Redox titrations : Oxidation of metallic Iron by Potassium Dichromate
0.31 g of an alloy of Fe + Cu was dissolved in excess of dilute $\ce{H2SO4}$ and the solution was made upto 100 ml. 20 ml of this solution required 3 ml of $\frac{N}{10} \ce{K2Cr2}\ce{O7}$ solution ...
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Derivation of "activity coefficient form of the Gibbs-Duhem equation"
I'm trying to differentiate the excess Gibbs energy ($G^{ex}$) to get the activity coefficient ($\gamma_k$), which writes:
$$
\frac{\partial (G^{ex}/RT)}{\partial n_k} = \ln\gamma_k \quad (1)
$$
in ...
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When does osmosis stop?
In the figure given below:-
Since only solvent particles can move through semipermeable membrane, if we manage to keep pressure on both the containers equal say by keeping weights, will osmosis go ...
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Calculating the solubility product for a salt in a metal-metal insoluble salt electrode
When trying to find the solubility product of a salt in a metal - metal insoluble salt electrode, I find that I am getting a different answer if I consider the cell to be a concentration cell and if I ...
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What exactly are the stages of the reaction between an oxygen ion and a water molecule?
I found information on the website water.lsbu.ac.uk - Oxygen and water:
Between altitudes of $80-\pu{100 km}$, $\ce{O2^{\small{\bullet}+}}$ and $\ce{NO+}$ ions are the dominant cationic species. $\ce{...
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Is ionisation enthalpy physical property or chemical property?
Ionisation enthalpy means energy change when an electron is removed.
According to Wikipedia
A chemical property is any of a material's properties that becomes evident during, or after, a chemical ...
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Term symbols in transition metals and lanthanides
Hello I was researching a little about term symbols of lanthanides and transition metals and have got two questions.
It is known that lanthanides don’t follow LS-coupling, but instead JJ-coupling. ...
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Can this equation be balanced using ion-electron method?
Reaction:
$\ce{C2H4 + O2 → CO2 + H2O}$
I want to balance the above reaction using the ion-electron method.
My attempt:
Ox-half: $\ce{C2^(^-^2^)H4 + 4H2O → 2C^(^+^4^)O2 + 12H^+ +12e^-}$
Red-half: $\ce{...
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Can all equations be balanced using ion-electron method?
Consider the reaction of a mixture of $\ce{C2H4}$ and $\ce{CH4}$ with $\ce{O2}$. Using the hit-and-trial method, this is the balanced chemical reaction:
$\ce{C2H4 + CH4 + 5 O2 -> 3 CO2 + 4 H2O}$
...
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Why don't P graphs contradict Raoult's law graphs?
Our teacher gave us the following question:
1 mole each of liquids A, B are mixed in a piston-type vessel and piston is moved slowly and isothermally. (PA0 = 75 torr and PB0 = 25 Torr)
Find:
(a) ...
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Is there any equation to predict the salting out concentration of a polymer?
I have to roughly calculate the salting out concentration of a polymer with respect to NaOH.
Is there any method to calculate?
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What's the reason of curvature in Tanabe-Sugano diagrams?
Analysing Tanabe-Sugano diagrams it's evident that some of the lines are pretty parallels to that of the ground field whilst others are inclinated or have some curvature.
I know what's the effect on ...
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Concentration term PPM [duplicate]
What volume do we assume when the concentration is written as mass by volume ppm?
I mean when mass by volume percentage is say 20%, we can say that 20g solute is present in 100 ml solution.
So if it ...
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Determining the molar mass of a substance by the osmotic pressure as a function of a mass concentration
Let's say that I have a solution of some substance in some solvent. The density of the solute is $\rho_\text{solute}$ and the density of the solvent is $\rho_\text{solvent}$. Suppose that the osmotic ...
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Formula derivation for adiabatic process
$\pu{1 mol}$ of an ideal gas at $\pu{400 K}$ and $\pu{10 atm}$ is allowed to expand adiabatically against $\pu{2 atm}$ external pressure. Find the final temperature of the gas if it is diatomic.
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What is the diffusivity of colloidal Formazine in water?
I have synthesized Foramzine in an aqueous solution (turbidity = 4000 NTU), and will be further diluting it. I would like to know the diffusion coefficient (diffusivity/mass diffusivity) of colloidal ...
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What is the relation between cross-section and spectral line intensity?
I was told by my supervisor that there is a relation between these two and he talked about a coefficient connecting the two of them. I am currently brushing up a lot of chemistry as I'm a physics ...
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Is the order of 1st ionization energies and order of the work function between some metals the same?
I understand that the ionization energy and the work function are two different terms both used in different contexts. But as a highschooler, I have learnt more about comparing 1st ioniztion energies ...
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What prevents an octahedral complex from always assuming the quadratic planar limiting case, due to the Jahn–Teller distortion?
When a given high-spin complex is Jahn–Teller distorted, this does not change the relative position of the total energy of the complex (assuming $\mathrm{d^{10}}$ configuration).
Indeed, the ...
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Eigenfunctions of total angular momenta as linear combinations of Slater-determinants
In the Hartree scheme for many-electron atoms, the approximated Hamiltonian (in a.u.)
$$\hat{H} = \sum_{i=1}^Z \left(-\frac{1}{2} \nabla_i^2 -\frac{Z}{r_i} + V_\text{H}\left(r_i\right)\right)$$
is ...
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Integration of Artificial Intelligence in Chemistry [closed]
How is Artificial Intelligence impacting the design and discovery of new compounds and medications?
Given the rapid advancements in artificial intelligence and machine learning methodologies over the ...
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Reduction of direct product representation
When we do the reduction of the reducible representation generated from the total wavefunction expressed as product of MOs of appropriate symmetry, we can find the direct sum of more than one ...
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Group theory and exact Eigenfunctions of Hamiltonian
I think I've understand why the real Eigenfunctions of Hamiltonian belong to a given irreducible representation and I've read that also MOs have to transform as irreducible representation due to the ...
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What does the 2 in t2g stand for?
I have read so far that it is about whether the d-Orbital is symmetric to a C2 element perpendicular to its main rotational axis. If all the given orbitals in a group are symmetric to that element, ...
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Commutating operators of angular momenta
I've studied the formal procedure to pass from the uncoupled basis set of individual angular momenta to the coupled basis set of total angular momenta for polyelectronic atoms.
I start from an ...
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Why is there internal energy change in a bomb calorimeter?
In a bomb calorimeter, the reaction occurs at a constant volume, hence we say that the heat absorbed by the water in the surroundings is equal to the change in internal energy for the reaction. But, ...
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Can we add specific conductivities at any concentration?
Suppose we have specific conductivities of $\pu{0.1 M}$ $\ce{K+}$ and $\pu{0.1 M}$ $\ce{Cl-}$. Can we add their specific conductivities to get specific conductivity of $\pu{0.1 M}$ $\ce{KCl}$?
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What is the difference between using an oven or an IR lamp to dry the coatings of fuel cells?
I wondered how the morphology of the catalyst coating for fuel cells changes if it is dried either in a conventional oven (40 °C, 60°C, 80°C) or under an IR lamp.
I am pretty certain that it changes, ...
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Some advice on inorganic textbook [duplicate]
I'd like to have some advice on Inorganic textbooks.
I've already consulted some books (Kettle, Drago, Keiter, Cotton) and they are all very useful, but now I'm searching for a textbook which focuses ...
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How exactly does the Nernst equation account for temperature? [duplicate]
I am doing an experiment that involves changing the temperature of the electrolytes in a voltaic cell and seeing the effect on the initial voltage produced. I'm a bit confused because if I use the ...
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Doubt on vibronic transitions
When we justify the presence of electronic transitions forbidden by Laporte selection rule, the coupling between electronic and vibrational states help us. Why we say that in this way we are ...
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Can an electrode run out of the active species?
I have a background in solid state physics but am new to electrochemistry. I have been following the example of a physical chemistry (Mortimer) book that looks an electrochemical cell with a hydrogen ...
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Nephelauxetic effect and covalency of metal-ligand bonds
As I was reading about nephelauxetic effects, which is the effect that atomic d-orbitals are bigger in a complex than in gaseous metal ions. The Racah interelectronic repulsion parameter gets smaller, ...
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Principal quantum number and 'good' quantum numbers
When we discuss about configurations we specify n, l, m quantum numbers for the individual electrons.
My question is: why when we pass from configurations to atomic terms in order to use the total ...
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Why is iron(III) more stable than iron(II)?
What I have seen, and what has been answered before (Why Fe 3+ is more common than Fe 2+), is that it is due to the half filled d orbital of $\ce{Fe^3+}$ compared to $\ce{Fe^2+}$. I don't understand ...
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Relative magnitude of the crystal field and spin-orbit coupling
In the EPR part of the book 'Physical methods in Inorganic Chemistry' by S. Drago i found that relative magnitudes of crystal field and spin-orbit coupling affect the g values.
I understand that the ...
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Alleged temperature dependance of activation energy?
According to Master Organic Chemistry (https://www.masterorganicchemistry.com/2012/09/10/elimination-reactions-are-favored-by-heat/), in point number four, the activation energy for a reaction is ...
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Electronic transition of iodine and non-bonding orbitals
As you all know, iodine has a purple color when in the vapor phase and when dissolved in non-coordinating solvents such as carbon tetrachloride. What electronic transition is responsible for this?
A ...
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Liquification of ideal solution of two liquids from vapor phase [closed]
A and B form an ideal solution. In a cylinder piston arrangement, $\pu{2.0 mol}$ of vapor of liquid A and $\pu{3 mol}$ of vapor of liquid B are taken at $\pu{300 torr}$ and $T~\pu{K}$. At what ...
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If I burn a compound, it gives a specific color. So can I find out the elements of the compound using that color it burns with? [closed]
For example NaCl burns with yellow-orange colour. So can I find out the elements of the compound using that color(Assuming that I don't know the compound)?
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Isochoric heating of a mixture of ideal gases with different heat capacities
I was thinking about the following situation:
Suppose we have an equimolar mixture of 1 mol argon gas (C=1.5 R) and 1 mol of nitrogen (C=2.5 R) and we heat it isochorically with 10 kJ from room ...
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Degeneracy of term symbols
Hello I was watching this video where term symbols are explained in detail. Moreover, he gives following illustration of a 2p1 state of hydrogen:
His calculation for the degeneracy is correct, ...
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In collision theory why we multiply collision frequency by N/2?
In kinetic theory of gases we know that the average number of collisions, $N_\mathrm{col}$, is given by
$$N_\mathrm{col} = \sqrt{2\pi\sigma^2 \overline{v}_\mathrm{rel}}\ N $$
where $N$ is the number ...
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Concentration units for kinetic mechanism of combustion
I am reading Tamás Turányi & Alison S. Tomlin's Analysis of Kinetic Reaction Mechanisms (2015). On page 10-11, the authors state that for a mechanism with $N_R$ reactions involving $N_S$ species, ...
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Enthalpy of reaction and work
Hello I am currently struggling with enthalpy of reaction and its use cases.
Let's say I am conducting the following reaction in a piston as a closed system:
$$\ce{C2H4(g) + 2 O2(g) -> 2 CO(g) + 2 ...
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Sodium Citrate / Sodium Phosphate Buffer Calculations
I'm trying to work through the calculations of a specific paper (linked here / below) but, my numbers are way off and I can't get them to match for the life of me. I need to make the same buffer but ...
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What is the reaction between crystal violet and bleach (sodium hypochlorite) and what is the mechanism of its action against crystal violet?
I'm trying to find the reaction between bleach (sodium hypochlorite) and crystal violet, and need to find the mechanism of its action, as during my lab investigation the bleach did cause the crystal ...
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Gibbs free energy of transition and activation energy
Let's consider a reaction A (reactant) -> B(product) and activated complex is denoted by C.
This graph ( potential energy vs reaction coordinate ) tells us that reactant need some amount of ...
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Is half-life defined for a reaction or for a reactant?
Consider the following chemical reaction.
$$\ce{A + B -> Products}$$
If this is a zero-order reaction with respect to $\ce{A}$ and $\ce{B}$, then is there a half-time for this reaction? Or must we ...
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