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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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How to quantify the mixing of two hard-spheres gases?

Suppose that there are two types of hard-spheres gases ($a$ and $b$) in a box. Suppose that their radius is much smaller than the box's characteristic size. These two gases tend to repel each other. ...
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1answer
27 views

Given two substances of different specific heats, how do you find the final temperature and these phase related things

Given two substances of different specific heats, how do you find the final temperature of them both, phase of either substance if there was a phase change, and how much either substance has changed ...
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37 views

Does hot water turns to ice quicker than cold water? [duplicate]

I kept hot water by mistake in freezer and noticed that it turned to ice pretty quickly and then I simultaneously put hot and cold water in freezer, still the results were the same. How so?
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59 views

Champagne bubbles and gravity

One of the influences on bubble size is the speed with which a bubble rises in a glass - this, I believe, is due to the force of gravity which acts on the liquid around the CO2. The greater the ...
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64 views

In the value of gas constant $R$, what kind of mole is it?

Wikipedia gives $$R=8.3144598(48)\, \rm J\,mol^{−1}\,K^{−1}$$ But I want to ask how is it possible to write $\mathrm{mol}$ without a suffix? I mean, we must determine if we have $1\ \mathrm{mol}$ of ...
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25 views

Diffusion of liquid in sealed reservoir with no empty volume?

Think of this scenario... You have a sealed container of some sort filled with water and some sort of mystery fluid X. Let's say this mystery fluid X has a density of 1.5g/cm^3. In this container, ...
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2answers
53 views

Does stirring a liquid add heat $Q$ to a system? [closed]

I was given a question, "A thermos bottle containing milk is shaken vigorously. Consider the milk as the system. (a) Will the temperature rise as a result of the shaking? (b) has heat ...
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48 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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40 views

What are the factors affecting equilibrium constant in a chemical reaction? [migrated]

In my class, it was taught that the equilibrium constant does not vary with the intial concentration? Why is it so?
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0answers
28 views

To which all factors chemical equilibrium is directly proportional to? [closed]

The equilibrium constant is directly proportional to the concentration. why it is so? Is chemical equilibrium dependent on temperature and other such factors? Then why we only focus on concentration?
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29 views

Writing specific heat of an element in terms of molar mass?

I'm trying to determine an expression for specific heat (J/(kg*K)) of a pure element in terms of the boltzmann constant and molar mass (kg/mol). I came up with this expression: specific heat = ...
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is fog matter, I knowthat stuff like fire arent but is fog matter? [closed]

I haven't found any other website which explains to me that fog is matter; I just need this to figure out what things are matter and which are not. For example, fire is NOT matter.
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Atomic bonding forces -

I was watching IBM's short film called How to move an atom and it got me thinking the following: What element would one use as a surface in order to get the lowest ...
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1answer
23 views

Does the presence of a flame affect the flow rate of gas out of a lighter or torch?

If I were to set a propane torch's valve to a fixed open position, would it run out of gas faster lit or unlit? Does the flame produce any kind of pressure change that affects the flow rate through ...
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1answer
98 views

Scientific explanation for smell? [closed]

This might be more on the philosophical side. We already know a lot about light. How it is generated and how it interacts with a material. Phenomenon such as Interference, Diffraction, the ...
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2answers
79 views

Physical meaning of quantized energy of electron (or n=1,2,3…) in Bohr's model

To solve objections on Rutherford's model, one of which is energy deficit, Bohr postulated that the energy of the electron is quantized and $n=1,2,3...$ . But what does this postulate mean physically? ...
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75 views

How did we first discover oxygen exists as $\rm O_2$ and not just $\rm O$?

How did we first discover oxygen exists as $\rm O_2$ and not just $\rm O$ ? (similarly hydrogen as $\rm H_2$ and not $\rm H$) I vaguely remember knowing a story about how the chemical formula of ...
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46 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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20 views

Charge distribution in the Inner and Outer Helmholtz Plane (electrical double-layer theory)

The Gouy-Chapman double-layer model predicts the presence of a diffuse layer of ions in an electrolyte solution when approaching a charged surface. But in order to take into account the finite size ...
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57 views

What is the best book or site to understand how to construct Periodic Table, theoretically?

I want to understand how Periodic table is constructed theoretically and mathematically. But I can't find self-contained book or site about it by myself since I'm a computer science guy and lack of ...
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1answer
58 views

How many calories in a block of wood?

I was recently thinking about the human body and the energy we get from food. I understand we don't have the ability to properly digest certain things like stones and wood and grass, but if we did, I ...
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47 views
+50

How to use Hund's third rule for excited electronic configurations?

Hund third rule states: For a given term, in an atom with outermost subshell half-filled or less, the level with the lowest value of the total angular momentum quantum number ${\displaystyle J\...
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Usage of pure substance chemical potential for the mixture of gases

There is a known expression relating the change in the Gibbs energy of the ideal gas to the change in pressure under the constant temperature $T$: $$\Delta G = nRTln\frac{p_f}{p_i} \tag{1}$$ where $n$ ...
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Is $H_2O$ the only compound which has a density anomaly? [duplicate]

My question is simple: are there any elements, compounds or materials other than water ($H_2O$) which have a density anomaly characterized by a turning point in the $T-\rho$ curve?
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1answer
21 views

Which elements or isotopes can be analyzed by Neutron activation analysis (NAA)?

Some sources name only a handful, but that might refer to the use of optical film. Others state more than 70. I would like to know which elemets or isotopes can be detectet/imaged by NAA.
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For the $\mathrm{H}_2$ molecule which spin states correspond to bonding? and which spin states correspond to anti-bonding?

Do I understand correctly? In the case of the $\mathrm{H}_2$ molecule, the overall state is $S = \Psi(r)\chi(s)$.....(Spatial and spin aspects) $\Psi(r)$ is inherently anti-symmetric under exchange ...
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2answers
47 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
47 views

Water Bottle Condensation

My friends and I were at a party last night and we were crushing empty water bottles until the cap popped off and water vapor came out. I have two questions regarding this phenomenon. From previous ...
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67 views

How many Vibrational degrees of freedom does a diatomic/triatomic linear molecule have?

I looked it up and found the formula to calculate number of vibrational degrees of freedom.I got it how they came up with this formula. It was (3N-5) where N stands for total number of atoms in a ...
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18 views

Why it is the Schottky defect not non stoichiometric?

Why Schottky defect doesn't counted under non stoichiometric defects? According to me since they lose atoms their stoichiometry must change.
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1answer
72 views

How do scientists experimentally (this means not theoretically) determine that an atom is not bonded with any other atom?

What I do not understand is how scientists can tell whether or not an atom is bonded to another atom or all by itself. If someone can help me understand this, please do.
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1answer
43 views

Why is it not possible to dope semiconductors with elements with 6 or 2 valence electrons?

As far as I have learnt, semiconductors are often made using elements from the 4th group, and their properties are often enhanced by doping with either pentavalent or trivalent elements. Take the ...
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2answers
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Methods to convert nitrogen nuclei to oxygen nuclei?

Are there any "safe" method that allows converting the nitrogen into oxygen? There's Ernest Rutherford that uses alpha particles aimed at the nitrogen to create oxygen and hydrogen. But are there ...
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2answers
149 views

Why doesn't Coleman-Mermin-Wanger theorem contradict phase transitions in systems with 1D reaction coordinate?

How does both hold: Coleman-Mermin-Wanger theorem continuous symmetries cannot be spontaneously broken at finite temperature in systems with sufficiently short-range interactions in dimensions ...
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53 views

Why does bread sticks on a hot pan? [closed]

What causes a slice of bread when placed on a non stick (hot) pan without much oil/butter to stick to it. And why does it not in presence of butter or oil ?
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31 views

Döbereiner's Law Explanation Required?

I wanted to ask why do the middle elements in the triads have masses average to the other elements in the Döbereiner triads ?
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1answer
43 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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Stability of saturated energy levels

In The Feynman Lectures on Physics, Vol. 3, Section 15-5, there's a discussion of the stability of various benzene ions. It turns out that the ions for which the all the energy levels up to a certain ...
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1answer
46 views

Does corrosion of metals depend on electron degeneracy pressure?

Corrosion is about losing electrons for the corroded metal and gaining electrons for the oxidising substance. Is it correct to assume that what controls this process is the electron degeneracy ...
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71 views

What happens to the chlorine in epichlorohydrin when a two-part epoxy is air-cured?

Where does the chlorine go? Does it evaporate as a by-product or does it remain in the epoxy? I'm using a two-part resin and hardener and curing them at room temp. The resin is bisphenol-A-...
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32 views

Particle in a box as easy model for molecules

I am trying to use the particle in a box model as a simplified model to calculate the energy difference between HOMOs and LUMOs of a molecule. The molecule I work with is made out of n phenyl-groups. ...
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13 views

Formula of a non-stoichiometric compound from mole ratio

For example, in Simkovich, George. Transport in nonstoichiometric compounds. , it is given that the mole ratio of Cu and Fe is 1.33:1.00. From that the compound formula is written as Cu1.244Fe0.933S2....
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Why does the Anode and not the Cathode corode during eletrolysis of water into $H_2$ and $O_2$?

After experimenting with the production of Hydrogen from salt water, I kept on noticing that the Anode (-) gets coroded and not the Cathode (+). Is it perhaps that water in itself is a naturaly ...
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31 views

Under what conditions can molecules exist?

I am curious to know the conditions required for any two or more atoms to bond together and form a stable molecule. Is their a set of rules that should be satisfied?
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3answers
51 views

Is it possible to power a car with chemiluminescence? [closed]

Chemiluminescence means substances that in a reaction emit light. I wonder if such a reaction would be possible to power an electric car using an photovoltaic panel lighted by the chemical reaction?
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2answers
734 views

What is the source for Osmium's colour?

The majority of metals are known for appearing grey to our eyes, cf. e.g. Why are most metals gray/silver? But the main exceptions to this are the "famous" group eleven metals, where their distinctive ...
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214 views

Sodium sometimes absorbs orange-yellow light, sometimes emits it? Huh?

Usually, we are told that sodium emits orangish-yellowish light, which is why city streetlamps are that color. Now, I read in New Scientist magazine that exoplanet WASP-96b is bluish because the ...
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2answers
90 views

What happens if Jupiter is ignited?

I was wondering, what would happen if there was a large amount of oxygen released into Jupiter's atmosphere, than igniting it? Because Jupiter is 90% gas, therefore being a big fire waiting to happen (...
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Literature covering Hund's coupling case and anomalous Zeeman effect

I am taking a course in cold chemistry and different types of interaction seem to be an important cornerstone in the course. I am looking for a book that might cover the topics of molecules in ...
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19 views

What is the probability function for a molecule having energy in a certain mode, taking the minimum required quantum energy of that mode into account?

I understand that the probability density for a particular velocity v+dv in one dimension for a molecule in a system is: $$f(v) = \sqrt{\frac{m}{2\pi k_B T}} \cdot e^{\frac{-mv^2}{k_B T}}$$ I'm ...