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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Parkhomov's E-cat reproduction [closed]

In the beginning of the year, Professor Alexander Parkhomov of Lomonosov Moscow State University claimed to have replicated (as read in e.g. Wired) of the E-cat functioning, albeit with lower effect. ...
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2answers
784 views

Gibbs free energy + maximum work

The Gibbs free energy is the maximum amount of non-expansion work that can be extracted from a closed system; this maximum can be attained only in a completely reversible process. This maximum work is ...
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2answers
66 views

Molecules from atoms [closed]

Why does two oxygen atoms combine to form a molecule and not 3 or 4?Also why does one sodium and one chlorine atom combine to form NaCl while two chlorine atoms are required to combine with one ...
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1answer
82 views

What happens if a free radical is placed in absolute vacuum?

I'd like to know what happens if a free radical has no material around to interact with. I have asked many people but I am not satisfied with their answer. I know there is nothing like absolute ...
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63 views

Exothermic heat release mechanism in gases

How is heat released when bond formation occurs in gases? For example, when atomic oxygen and molecular oxygen combine to form ozone?
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2answers
131 views

Could we describe acids and bases using electromagnetism?

Why don't we use Maxwell's equations in acids and base theory? Surely the interaction between two charged species is readily described by this. The theory I have so far come across is HASB theory. ...
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216 views

why do we Carbonate drinks not any other gas

Carbonation is done in all fizzy drinks. Also it forms a small amount of carbonic acid which we feel on our tongue. We can diffuse oxygen as well in the water at higher level. Except for acid ...
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1answer
1k views

Are valence electrons in nonpolar molecules localized/delocalized?

Are valence electrons in non-polar molecules localized or delocalized? I'm quite confused about the whole electron localization and delocalization business. I'd love a simplified explanation that a ...
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41 views

When is energy transferred to/from atoms mechanically (vibration, rotation) vs photons?

In reading intro quantum mechanics and chemistry text books there is a lot of talk about energy transitions in atoms due to photon absorption/release. However atoms can also absorb and release energy ...
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27 views

Query about change in $\Delta G$ during a chemical reaction and finding equilibrium

TLDR : Can someone explain the graph at 27:40 in the following lecture: Full section length is from 21:12 to 27:40 https://www.youtube.com/watch?v=Cc2l1QTTZA4&list=PLA62087102CC93765&index=...
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41 views

What is a “Doppler instability”?

In the paper "Flow-induced control of chemical turbulence" by Berenstein and Beta, the term "Doppler instability" is mentioned in the context of the Belousov-Zhabotinsky reaction. I am looking for a ...
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37 views

Why can't adiabatic changes decrease entropy for a closed system?

I read that adiabatic changes in a closed system can never decrease the entropy. To try to understand why, I thought of two scenerios: reversible processes, and irreversible processes. For a ...
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39 views

Confusion about internal energy and temperature during a phase change

During a phase change, internal energy of a system will change because energy must be added or subtracted (depending on "direction" of change) from the system in the form of latent heat. However, the ...
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38 views

Details of forces involved in osmosis at a microscopic level

Well I read about osmosis from different sources and most of the chemistry books did not delve into intricate details so I consulted many sites to get the physics approach to osmosis and they mostly ...
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1answer
23 views

Shouldn't the remaining photon energy be transferred to both electron and ion in a photoionisation?

I'm studying photoionisation and photodissociation, and I'm having a hard time trying know the microscopic details of such processes. I've read that in a photoionisation the photon is absorbed by a ...
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1answer
30 views

Which reference should I use for molar masses of chemical elements?

This question is more related to the academical application of Physics than to Physics per se. I'm currently doing my thesis, and it involves a lot of molar masses in the calculations. I would like to ...
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87 views

Predicting pressure of propane gas in container based on temperature

I'm a mathematician and computer scientist, and for this particular problem I would benefit from some physics/chemistry expertise. I've already asked this question on chemistry stack exchange, but I ...
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1answer
53 views

How will the Big Rip affect chemistry and nuclear interactions?

The "Big Rip" is a theoretical scenario for the death of the universe. Let's assume that this scenario is true. What can we expect to happen to chemistry and nuclear interactions in the time ...
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1answer
154 views

What is the law of mass action?

What is the law of mass action? This is a question which covers the area of chemistry. But unfortunately I don't know any sites which can clear my chemistry doubts. So kindly I request anyone to ...
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1answer
77 views

Basic energy question

How do we know something contain energy or not? P.S.: I don't really understand how energy should be interpreted. Until today I always thought that energy is some kind of magic that makes stuff ...
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2answers
393 views

Chemical potential and equilibrium condition

My question is about the $dG=0$ condition for the equilibrium in a system, say, solid + gas (water and ice, if you prefer). Almost every textbook gives the following recipe to understand phase ...
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1answer
76 views

How To Calculate The Gibbs Energy Of A Molten Salt

If I have a molten salt of known composition, pressure, and temperature, is there a way to find the Gibbs energy of the substance? I'm not talking about the change in gibbs energy, I mean H-TS
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1answer
52 views

Why do the sun and planets differ in their chemical elements composition?

The chemical elements composition of the sun changes as its nuclear furnace changes elements into heavier ones. But it is supposed to be mostly Hydrogen at the start. The planets are too cold for ...
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25 views

Multi-stability potential is suitable for interdisciplinary branches of science?

The potential function $V(x) = c(x-a)^2(x-b)^2$ with constants $a,b,c$ and some variable $x$ has two minima: One at $x=a$ and another at $x=b$. When plugging this potential function in Newton's ...
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203 views

Is the rate of evaporation in the below mentioned situation constant when liquid vapour equilibrium is not reached?

i am studying liquid vapour equilibrium and there is the set up (below) for the experiment.The conditions:temperature is constant throughout. in this case is the rate of evaporation of the liquid ...
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1answer
233 views

Can a plasma ball light up minerals that fluoresce?

I want to know if I could use a plasma ball to light up a UV poster that are typically activated by blacklights. option 1: using light from the globe According to my research it seems that the light ...
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2answers
50 views

Why do we need to add proton and neutron as same number to figure out the weight of it?

For example, the Carbon is number 6. That means it has 6 protons. If we add the 6 neutron the total is 12 and we call it carbon 12. 1 neutron and 1 proton equal as the 1 atomic mass unit. That means ...
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447 views

What generates most heat in a rifle barrel, burning gunpowder or friction?

As anyone who's done some shooting quickly finds out, it does not take very many rounds to heat up a barrel to be too hot to touch. A lot of folks think the 'burning of the propellant, and its ...
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1answer
101 views

Why are atoms so different from one an another? [duplicate]

An atom is composed of a positively charge nucleus, with a cloud of electron(s) around it. But I can seem to understand the huge differences between 2 components that seem so close in terms of what ...
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1answer
52 views

How to estimate the index of refraction of a material based upon its chemical composition

I want to be able to estimate what the index of refraction of a material is based upon the chemical makeup of the material. For example what equation would I use to estimate the index of refraction ...
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1answer
34 views

Does an activated complex have a specific heat capacity?

An example of an activated complex is two atoms so close (due to collision or attraction) that they are both in the highest energy state before reaching the lowest energy state at which they can be ...
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1answer
126 views

Bubble Formation in Froth Flotation process

I've recently attended a lecture on the metallurgical process of froth flotation. To make us understand froth, my teacher gave us the example of soap bubbles. But in actual practice, the flotation ...
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180 views

Vapour pressure of a liquid

Today I studied that vapour pressure of a liquid is constant at a given temperature. I want to ask that "how do we determine the vapour pressure at a given temperature? " Also since evaporation causes ...
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772 views

To freeze salt water

Does the salt water requires more energy to be freezed with a fridge compared to distilled water? If so, why and how much more?
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1answer
2k views

Excess Gibbs Free Energy

I am having some confusion with something my professor has written and would like to have this issue cleared up. I'll start from the beginning, I understand all this, I'll mention where it stops ...
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1answer
106 views

Solution with salts

Does a solution of water and NaCl increase its volume of the same amount of the volume of salt added? Thank you Does the ions Na+ and Cl- taken separately ,occupy more space than the binded molecule?
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1answer
93 views

A question about thermodynamics (endothermic reaction)

I am probably getting lost in a cup of water but.. better to clarify. So, my book makes an example of an strong favorable endothermic reaction (so much that the bin [the can] does freeze with all the ...
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1answer
35 views

why objects in nanoscale obtain their distinctive properties? [closed]

I know the properties of matter come from intermolecular or intramolecular forces. and if they change, the properties of matter change , or it could be the matter itself. but what happen when we ...
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1answer
163 views

What materials can be used to prevent the settling of particles in the ceramic slurry? [closed]

How can we avoid the Settle particles in the ceramic slurry? What materials can be used for this purpose?
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1answer
977 views

Exceptions to the Aufbau principle?

Why are there exceptions to the Aufbau Principle? How do the abnormalities occur and why? If you could specify a few exceptions that would be swell.
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1answer
119 views

Ionic crystals and conduction of electricity?

Why do solutions of sodium chloride conduct electricity but crystals of sodium chloride do not?
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1answer
64 views

How much approximately the pressure would drop?

A container made from from aluminium ($0.5~\mathrm{mm}$ thickness $10^3~\mathrm{cm^3}$) closed system , it has 50 psi (nitrogen) pressure inside at temperature $80^\circ~\mathrm C.$ Approximately : ...
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1answer
283 views

Total chemical potential of electrons in pn junction

I am reading this page about electron energy concept terminology. I am trying to apply that for the pn junction in equilibrium below. Could anyone help me to see if I get it correctly? C = ...
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1answer
129 views

How much salt to dissolve in water for a noticeable change in volume?

I am reading through this High School science lab about how dissolving salt changes the volume of water: Place 300 to 400 g of salt in the flask (1L) Pour in enough water to cover the dry salt, and ...
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1answer
81 views

Why is beta-minus decay considered isobaric?

Page 20 of Physics in Nuclear Medicine says that beta-minus decay is isobaric (eg the A/Z ratio remains the same). The reason it gives is that "mass number A does not change." However, in beta-minus ...
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2answers
2k views

Gaining or Losing Too Many Electrons

So I understand that an atom can gain or lose electrons and still retain it's identity - for example a Carbon atom is still carbon even if it loses 5 of it's 6 electrons because it is the number of ...
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1answer
90 views

Interparticular space

We say that the inter-particular space in solids is small,in liquid is intermediate and in gas it is huge.So,how small is that space.there must be parameters for the amount of space.Like when the ...
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1answer
182 views

Physics behind blowing soap bubbles

Is it possible, using the surface tension of a soap bubble, to calculate the maximum pressure (created by the air flow) it can withstand while still attached to the orifice to prevent it from bursting?...
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1answer
801 views

Calculating with quantum numbers and shape of nodal shells

I'm attending in a chemistry course now, and in the beginning we scratch the surface of the quantum physics, which have led me to some problems. Mostly I understand all what we get until now, but ...
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1answer
1k views

Calculate how many photons hitting a sample that are absorbed

In the determination of the quantum yield of a photoisomerization, $\Phi,$ the following is needed $$ \Phi = \frac{\mbox{Number of "reactions"}}{\mbox{Number of absorbed photons}} $$ The photon flux ...