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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Calculating rocket thrust

for my recent project I'm trying to compute somewhat accurate rocket physics (although approximations are good enough - for example for aerodynamics). The project is about making "game-like" ...
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1answer
42 views

Physical reason of adding salt when we're cooking rice (osmosis)

Why do we add salt when we're cooking rice? I know one reason is related to the boiling point of water but someone said it is also related to "Osmosis". What is the relation between adding salt and ...
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Does anybody know how much heat an otto ic engine produces? [on hold]

When the engine is working, it produces torque(useful) and heat(not really). Does anybody know the proportion of torque/heat an average gasoline engine produces? Thank you.
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51 views

Velocity from the cumulative distribution function of the Boltzmann distribution

I want to get a Boltzmann distribution of the $v_x$, $v_y$ and $v_z$ velocity components (please, notice that the distribution is one-dimensional). To do so, I need the cumulative distribution ...
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37 views

Chemistry of water under pressure [closed]

What is the structure of water under extreme pressure, like the bottom of the ocean on a moon like Europa.
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10 views

Do the isotopologues of a compound affect it's cracking patterns in a residual gas analyzer?

For instance, CO2 is listed as 100% of the peak at 44, 11% of the peak at 28, 9% of the peak at 16, and 6% of the peak at 12. But now consider CO2 comprised of C13. obviously the peaks would be at ...
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1answer
56 views

Why is it easier to remove stains with water?

And I don't mean stain removers, but literally tap water. See here's the thing, you can't remove a stain without some sort of friction, and water reduces friction. Yet if I say, spill some coffee and ...
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1answer
29 views

Conformational Analysis of Ethane and Butane

How does a condensed matter theorist explain conformations of Ethane and Butane using tools from Quantum field theory? If they don't how do they calculate energy differences and predict differences ...
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54 views

Would it be correct to state that all the forms of everyday matter (mountains, tables, buildings, people, etc.) are in a metastable state?

We had a fire going in the backyard of a friends house this weekend, and after thinking about the chemical reactions occurring in the wood (and anything else we threw into the pit), I started to ...
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19 views

How strong is the HCN Union when modelling with springs

I'm modeling the HCN Molecule with springs, giving the bounds between H and C the name k1 and between C and N k2. Is there any information of how strong is the bound? We were asked to get the ...
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2answers
59 views

Free Expansion Of and Ideal Gas

We know that in free expansion of an ideal gas, no heat enters or leaves the system. We also know that $P_\text{initial}V_\text{initial}=P_\text{final}V_\text{final}$ is valid. If heat exchange ...
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8 views

Energy Per Dry Ice Mass Required By de Laval Expansion of Air?

There has been a lot of talk lately about CO2 extraction from air. Since there are rocket engines in which ice crystals precipitate in the exhaust when expanding into near vacuum, it seems dry ice ...
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18 views

breaking bonds with light

Light, for instance green light (532 nm = 2.33 eV) has an energy comparable to that of many chemical bonds (C-C bond dissociation energy is about 3.6-3.7 eV). So how is it that I'm not being burned ...
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1answer
80 views

FCC-to-BCC phase transition in NaCl, Buckingham or Lennard-Jones potentials?

Background The transformation from B1 (face centered cubic (FCC) type) to B2 (body centered cubic (body centered cubic (BCC) type) structures is one of the best documented high pressure phase ...
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7 views

Butler-Volmer Anodic and Cathodic Activation Constant Proof

In the Butler-Volmer Equations, I have often seen the activation constant at the anode and cathode related by: $$ a_a=1-a_c $$ This is the relation used, for example, on plots of this equation on ...
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1answer
35 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
19 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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1answer
92 views

What is the desest material on earth? [closed]

Apart from the elements, do we know of materials that are denser? I.e. can an alloy be denser than the sum of its compounds, for example if the new lattice packs denser than each of the compounds it's ...
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27 views

How did scientists calculate the number of atoms in one mole of a substance? [duplicate]

Please explain me about the basic methods about how can we calculate that 1 mole of a substance contains 6.022140857 × 10 23 molecules? Tell how the modern scientists calculated it and how Avogadro ...
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31 views

What would be the best material to reflect radio waves?

I was thinking about what would be needed to build a parabolic dish and I inevitably came to what material to use. From what I could gather after a quick search on the internet, it would seem that any ...
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0answers
17 views

Copper vs Tungsten (Diffusion)

I've been studying on how to compare the activation energy for (void-) diffusivity of Copper versus Tungsten. I ended up finding $E_a[cu] = 1.1[eV]$ and $E_a[W] = 5.2[eV]$ in literature where the ...
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1answer
16 views

how does voltage sensitive dye determine the membrane potential?

There are so many papers about VSDs and how to use them, but i can not find anything about what exactly is happening in the cell membrane that leads to the change in VSD's light intensity as a sign of ...
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1answer
42 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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33 views

salt water conductivity

my book says the following on conductivity in water with ions. I am confused about why electrons from the zinc (anode) repel positive ions. Because zinc becomes negative, shouldn't it attract it? ...
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1answer
36 views

Quantum Mechanism Dipole Moment Magnetic Field Problem [closed]

I figured 1a out pretty easily. For 1b I am a bit stuck. So far i have that in the field: $$ \Delta z = v_0t + (1/2) a_zt $$ $$ F_z = ma_z $$ so $$ a_z = F_z/m $$ We know $$ ...
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Bimolecular and Isomerization reactions

Is it possible to describe a reaction of the $$ A+B \rightleftharpoons AB $$ exactly using the solution of an isomerization reaction? $$A \rightleftharpoons B$$ I just can not figure it out the ...
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1answer
38 views

Humidification Problem [closed]

Humidification Imagine that water is evaporating into initially dry air in the closed vessel shown schematically in Fig. 8.1-1(a). The vessel is isothermal at 25 C, so the water’s vapor ...
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2answers
226 views

Ranking bond types from strongest to weakest

Note: I've already handed this in for homework and got the question wrong but don't understand why. Not looking for someone to do my homework for me, just trying to flesh out an area where I'm not yet ...
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2answers
74 views

Why has a molecule less energy than the uncombined atoms?

My book says, A molecule as compared to the atoms from which it is formed is more stable because it possesses energy lower than the energy of the uncombined atoms. This difference in energy is due ...
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2answers
88 views

Boyle's Law-$ PV= nRT.$ What equation should be used to find pressure if n is not constant, like in an elastic system?

When air is added to an elastic system, like a balloon, the volume and pressure change. Would use Boyle's Law- $PV=nRT,$ but n does not remain constant in this situation. Known: $V_1$ is at ...
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1answer
51 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 ...
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1answer
40 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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2answers
78 views

How does electromagnetic radiations penetrate?

I am reading about the discovery of subatomic structure which includes all these things radioactivity, alpha rays, gamma rays, x rays et cetera. I read that electromagnetic radiations are energy ...
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34 views

What happens when a semipermeable membrane allows only one solute to pass through?

I'm essentially a medical student where we deal a lot with osmosis. But when we are taught, it is done generally with only a single solute in consideration. What if two different solutes are used on ...
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10 views

What would be a suitable textbook of first semester physical chemistry? [duplicate]

I am going to take PChem I in my biochem dept next sem, which is a watered down version of the PChem course in Chem dept. It basically covers thermodynamics and a little bit of quantum stuff. The ...
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1answer
33 views

What is the relation of particle velocity, temperature, and reaction activation energy

So, this curiosity has arisen for a fun project I thought I'd tackle, where I'm attempting create a crude simulation of an internal combustion cylinder. I wanted to explore the particle level ...
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1answer
60 views

Constant Temperature Cooling

In my thermodynamics textbook there is part of a question that seems to be a contradiction. ...Superheated refrigerant R-134a at 20 C, 0.5 MPa is cooled in a piston/cylinder arrangement at constant ...
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22 views

Gibbs isotherm and calculating interfacial tension change from first principles

Question: Is it possible for a solid particle to change the surface tension between two phases? (or: Does a solid particle have a chemical potential?) This question stems from the more ...
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4answers
117 views

The impatient hot tub owner [closed]

An impatient man owns a 300 gallon hot tub. He comes home from a hard day of work and sees that his hot tub is currently simmering at 90F. For maximum relaxation, he wants it at 104F. However, the hot ...
2
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1answer
35 views

“Carbon capture into fuel” - where does the energy come from?

I recently found an article titled "Scientists find a way to convert Carbon Dioxide from air into fuel" (here), and my immediate reaction was "surely not - the energy balance would kill you right ...
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1answer
63 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 ...
2
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1answer
61 views

Atoms attraction [closed]

Do atoms attract to atoms of same element? And would atoms attract to another atom for forming ionic or covalent bond? I basically want to know what would an atom be attracted to? (Except for ...
9
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2answers
224 views

In a Monte Carlo NVT simulation How do I determine equilibration

I'm running an NVT (constant number of particles, volume and temperature) Monte Carlo simulation (Metropolis algorithm) of particles in two dimensions interacting via Lennard-Jonse potential ($U = ...
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27 views

Do (or can) hydrogen bonds between water molecules neutralize their own polarity? [closed]

Do (or can) hydrogen bonds between water molecules neutralize their own polarity as indicated here: Hydrogen bonding as the mechanism that neutralizes $\mathrm{H_2 O}$ polarity ...
3
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1answer
70 views

Do sodium chloride(ions) melt the ice or not?

My question is this, In European countries, they use NaCl or KCl to melt ice during the winter season. In Asian Countries, they use NaCl to keep the ice without melting. (Ex- Ice cream boxes, Beer ...
2
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1answer
49 views

Why do randomly flying gas molecules have a distribution of energies?

Why do randomly flying gas molecules have a distribution of energies? This is a question from my chemistry textbook (not homework, just questions to help us think about and understand the concepts). ...
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1answer
36 views

How can we use conductivity measurements of water to find hydrogen ion concentration of water?

How can we use conductivity measurements of water to find the hydrogen ion ($\mathrm{H}^+$) concentration in water?
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46 views

Why dynamic equilibrium exists?

We know that at equilibrium Gibbs energy is minimum. We also know that at equilibrium both forward and reverse reactions occur simultaneously, and also we know that for a reaction to be spontaneous ...
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1answer
103 views

What causes an emulsion to be stable or unstable?

The other day I made a salad dressing based on oil and vinegar. To my understanding, there is a positive energy associated with the surface between the oil and vinegar. The most stable state is also ...
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1answer
72 views

Electronic spectroscopy question in a more physics oriented view. What is the operator that describes relaxation pathways?

Recently I was studying spectroscopy in Symmetry and Spectroscopy: An Introduction to Vibrational and Electronic Spectroscopy p.357-358 as shown in the image http://i.stack.imgur.com/LSLyZ.jpg The ...