Questions tagged [physical-chemistry]

Study of macroscopic and microscopic phenomena in chemical systems in terms of physical laws and concepts [thermodynamics, statistical mechanics, kinetic theory, quantum mechanics...].

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Will this be a self-sustaining system?

Will this be a self-sustaining system? Sabatier process: $$ CO_2 + 4H_2 = 2H_2O + CH_4 $$ Combustion: $$ CH_4 + 2O_2 = CO_2 + H_2O $$ Electrolysis: $$ 4H_2O = 4H_2 + 2O_2 $$ Respiration: $$ O_2 >=...
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27 views

Magnetic permeability of a mixture

How do you calculate the magnetic permeability of a mixture of two substances (e.g. alumina powder and boric acid) knowing the permeability of each one of them?
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1answer
32 views

How does quantum electrodynamics explain the movement of nuclei in chemical reactions?

In Feynman's third Douglas Robb Memorial Lecture (which took place in 1976 at University of Auckland), he states that: It's fine to approximate nuclei as a point, although they really aren't. Quantum ...
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3answers
39 views

Why doesn't a chemical reaction occur with the movement of electrons in the context of electricity?

In school it is generally taught that the movement of electrons between two atoms causes a chemical reaction. However, when it comes to electricity why doesn't a chemical reaction occur with the ...
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1answer
31 views

How do Acids behave in magnetic fields? [closed]

If we expose an acid (e.g. boric acid) to a magnetic field (low frequency ac field), how would it behave? Would it be attracted or repelled?
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Is the $g$-tensor describing the Zeeman effect for molecules always diagonalizable?

The Zeeman splitting of a molecule can be described through the $g$-tensor, which couples the magnetic field to the angular momentum of the molecule. Is the $g$-tensor always diagonalizable?
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What is the difference between ground state, excited state and transition dipole moment?

I need to find a transition dipole moment of Rhodamine 6G molecule, however they provide ground state and excited state dipole moment. Are they similar or can I somehow obtain transition dipole moment ...
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Optoelectronic Properties of Transition Metal Oxides [closed]

Where can I find some information about the most common transition metal oxides and their optoelectronic properties?
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1answer
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Physical interpretation of $pV= 0$ for Einstein Crystal Model

There is a difficulty with the pressure of the Einstein crystal model. The model does not include any simple way to evaluate the derivative in Eq. (28.2-7e). We might try to evaluate the pressure by ...
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What would happen if two liquids of different nature are mixed together?

I was studying surface tension the other day and this thought came to my mind. What would happen if say a liquid like mercury which has higher cohesive forces than adhesive ones(hence the convex ...
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Do noble gases remain in their atomic states rather than form molecular bonds such as other gases are known to exist?

Just had a passing thought that given the fact that noble gases are inert and do not interact with other gases due to the fact that the outer shell is full, it would be the case that in nature they ...
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42 views

A general way to combine equilibrium constants in reaction networks?

I have a network of states, each linked with neighboring states by unique forward and reverse transition rates ($k_{f}$ and $k_{r}$) - let's just say these are chemical species with multiple ...
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In spectroscopy, what element does green indicate presence of in the atmosphere?

And what element does visible green glow indicate in our own atmosphere? https://youtu.be/HDlsdVuv6qQ
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Does potassium ions have a longer range attraction than sodium ions or hydrogen ions?

Electronegativity decreases with period in in the periodic table. The explanation for that is because the distance to the nucleus decreases with each orbital shell of electrons, if I got that right. ...
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1answer
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Why change in Gibbs free energy of mixing is not zero?

I can't understand why change in Gibbs free energy must be zero when two ideal gases mix. The differential of $G$ is: $$dG=-SdT + Vdp + \sum_i\mu_idn_i$$ When two ideal gases mix and they are ...
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1answer
58 views

What is the basic physics mechanism behind photosynthesis? [closed]

Could a similar process be achieved artificially in a laboratory, with the same near perfect efficiency biological systems display. Is there a sound simple theoretical model on how this works?
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1answer
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Casimir effect evidence

How does the attraction between two metal plates support a new effect (or force)? Isn't it expected that two plates attract each other due to the London dispersion? If so, how does the experiment ...
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1answer
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Question about spectrum emissions

I was studying about spectrum emissions but I have a question. For example if I have $2$ electrons from different atoms with different distances from the nucleus, then I hit them with fire causing ...
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2answers
35 views

Understanding exothermic reactions (e.g. combustion) using Newton's laws

When reactants undergo exothermic reactions, e.g. combustion of hydrocarbons, energy is conserved when some energy in the chemical bonds of the reactants is transformed into kinetic energy of the ...
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Making water evaporate faster using chemicals

I've already seen this question, and it talks about any means in general. I just wanted to know if any chemical substances can be added to water to make it evaporate faster? Does addition of Edible ...
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Configuration Interaction for Hydrogen Molecule

Reading a book (introduction to computational chemistry, frank jensen, Chapter 4.4 The UHF Dissociation and the Spin Contamination Problem) on Quantum Chemistry, it introduces Configuration ...
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2answers
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What makes seasoned cast iron non-stick?

I get how Teflon works, but am curious how the act of seasoning cast iron makes it non-stick. Does this also work for other metals besides cast iron?
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1answer
56 views

How and why does an electron add up (enters) in the valance shell of an atom?

How does an electron add up (enters) in the valance shell of an atom? Why is energy released when an electron adds up in the valance shell of an isolated atom.
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Why does the ideal gas law exactly match the van't Hoff law for osmotic pressure?

The van't Hoff law for osmotic pressure $\Pi$ is $$\Pi V=nRT$$ which looks similar to the ideal gas law $$PV = nRT.$$ Why is this? Also, in biology textbooks, the van't Hoff law is usually instead ...
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67 views

Derivation of Boltzmann distribution using Stirling's approximation

I'm reading Physical Chemistry by Engel Reid and I have trouble with deriving the natural log of the weight of a configuration. $$\begin{aligned} \ln W &=\ln N !-\ln \prod_{n} a_{n} ! \\ &=N \...
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26 views

An increase of entropy is less at higher temperatures. Is the inverse true for a decrease of entropy?

So I have seen previous posts about how a change in entropy is relative to the temperature, and that an increase of entropy is less at a higher temperature, as explained by: $$\Delta S_{\text{...
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What causes the milk to suddenly rise up & spill out if not stopped?

Well, when milk is heated in a container its temperature starts rising & water vapor bubbles rise up through it. This initially causes a little and slowly rise in level of milk. But after certain ...
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The voltage across an electrochemical cell

Suppose I have a galvanic cell, like the one below In the other resources I checked (such as LibreTexts, Chem Pages, and Khan Academy), it is mentioned that the voltage across such a cell is ...
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How does ski wax (nonpolar liquid) dissolve into polyethylene (nonpolar plastic)?

Ive been reading alot about ski waxing and a reputable source said that when you iron in paraffin wax into the base of a ski or snowboard, the wax melts from the heat of the iron and dissolves into ...
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1answer
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Will ions in a solution emit radiation from an electric discharge?

If I pump enough current through a water solution with ions in it, will the ions in the solution emit EM radiation as the water heats up to form a "spark"/plasma? Basically trying to make an ...
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1answer
44 views

Where and how do particles move? [closed]

I've been thinking of making a simple 2d game of some sort involving particles and I've stumbled upon something I haven't really thought about. I know a lot about chemistry, so I'm not new to ...
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1answer
22 views

Can heat transfer break an equilibrium?

Here is one scenario: I have placed a metal in my room which is at room temperature. Air has little much heat capacity and metals don't like to store heat. Would heat transfer occur? Whatif I set the ...
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2answers
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Is there a way to experimentally determine the true mass of C-12 isotope which is defined exactly as 12 amu?

As most you know the measurement of atomic masses has > 200 year old history and atomic masses were deduced on the basis of chemical reactions by meticulous chemists until the 1940s. Later, mass ...
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Can we burn Ash? [closed]

Can we burn ash at any temperature ? Will it melt ? If i am talking about ash of paper. I actually collected several samples of ashes and tried to burn it but it didn't. Tell me wil ash change its ...
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Problems in deriving second law of thermodynamics in terms of Gibbs energy

I want to express the second law of thermodynamics in terms of Gibbs free energy, $dG \leq 0$. It is true that: $$dH=TdS+Vdp+\sum_i\mu_idn_i$$ and $$dG=-SdT+Vdp+\sum_i\mu_idn_i$$ So for constant $T,...
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1answer
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Mass-energy equation vs chemical bonding reactions

If use $E=mc^2$ in chemical energy like needs to bonding and ...  it means there must reduced or added some mass after reaction, by Wikipedia mass-energy equivalence: Because the speed of light is ...
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Beryllium Neutron Multiplier

We know that Beryllium is used in blankets of Fusion Systems because it is a neutron multiplier. I was wondering that if Beryllium is a neutron multiplier can it be used in the fission process(of ...
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1answer
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Interpretation of occupation numbers and creation-annihilation operators in strongly correlated systems

I hope I am not asking anything stupid, but I am having a hard time interpreting some (seemingly simple) results. The simplest approximate form of an $N$-electron wave function (w.f.) is a Slater-...
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1answer
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Physical chemistry during and after the big bang

been pointed here by another site. Grateful for any responses i receive. I'm an author not a scientist. For an article I'm writing I'm trying to describe the Big Bang in layman's terms. Specifically I ...
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188 views

Are exceptions to Klechkowski/Madelung rules understood *theoretically*, or are there known only from *experimental measurements*?

Some elements (example gold : Au, etc) don't follow follow Klechckowski rule for the ordering of the filling of the various quantum levels. One uses typically Klechkowski/Madelung rule to predict the ...
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Volume of Plasma as Compared To Gasses

When a material turns from gas to plasma state, does the volume increase, or does it remain the same? And if it does increase, does it depend on temperature and pressure?
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104 views

Derivation of the Poynting and Kelvin equation (Effect of external pressure on vapor pressure)

Consider a condensible liquid. Using the Clausius-Clapeyron equation one can derive an expression for the vapor pressure $p_{sat}$. This is the pressure at which liquid condensat and vapor coexist. In ...
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1answer
111 views

Lost volume data of water and isopropanol mixtures [closed]

WHO has two recipes for disinfecting, based on ethanol and isopropanol (IPA). They typically start with an alcohol volume and then top it off with the other ingredients to 10 litre. One of the recipes ...
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1answer
97 views

Does the EMF negate when a cell is being charged?

A defining equation of electrochemical cells is that the EMF, $\mathcal{E} = E_{red/cat} - E_{an/ox}$, equals the electric potential of the cathode minus that of the anode. This means that if a cell ...
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99 views

Water density as a function of temperature

I would like to know if there is an expression or a correlation to calculate water (not gas or steam) at different temperatures. If possible both nonlinear and linear temperature calculation. I only ...
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36 views

Diffusion Fick's 1st law for non-isothermal ideal gas

I have some doubts regarding diffusion. Let's imagine two chambers, with infinite volume, connected by a capillary. Both chambers are filled with the same gas, but at different temperatures, thus ...
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Meaning of spontaneity of reactions and change of spontaneity with varying conditions

We use the change in Gibbs free energy to predict whether a reaction is spontaneous or not in the direction is written. Consider a reaction which is endergonic. Does this mean that we expect no ...
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Does electromagnetic radiation cause auto-ionization of water?

The auto-ionization of water into $\text H^+$ and $\text{OH}^-$ is often described as occurring spontaneously, that at any given time a tiny portion of the water will be split into its cation and ...
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2answers
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Is every chemical reaction a nuclear reaction?

This is a PhD-level question that I'm sorry to say is likely to annoy many a high school teacher or university professor trying to get their students to understand the difference between chemical and ...
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68 views

Why we use $p_x$ and $p_y$ orbitals?

The wavefunction of $2p$ orbitals with $m_l=\pm1$ have the form: $$\Psi_{p_{\pm1}}=\pm \frac{1}{\sqrt{2}}r\sin\theta\cdot e^{\pm i\phi}f(r)$$ We can make linear combinations and get the $p_x$ and $p_y$...

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