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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Calculating collision diameter with viscosity, but not having the mass given

I've got a homework question i'm stumped on. The viscosity of the ethylene gas was measured at $99.8*10^{-7} \textrm{ N s m}^{-2}$ at $288 \textrm {K}$. Calculate the collision diameter in ...
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2answers
65 views

Derivation of a formula

I have a formula for finding the final temperature in an irreversible adiabatic expansion. $$T_2=\left[\frac{C_v+(\frac{P_2}{P_1})}{C_p}\right]T_1$$ where $T_1$ is the initial temperature. $C_v$ and ...
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4answers
709 views

Evidence of orbitals?

How do we know that there are different types of orbitals? For example, what evidence is there for the existence of p orbitals instead of there being multiple s orbitals (for example, why isn't the ...
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2answers
45 views

Can lattice enthalpy only be determined by the Born-Haber cycle?

Since we are able to determine the enthapy of formation experimentally, why it is impossible to determine the lattice enthalpy directly by experiment?
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1answer
12 views

OFET vs Traditional Transistors

What is the advance of OFET's (Organic Field effect transistors) over the traditional CMOS Transistors?
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1answer
48 views

Correlation between the virial coefficients and a & b in the corresponding Van Der Waals equation of state

I don't know where to begin with this question. A function f(x) can be expressed as a special power series called the Taylor expansion. The common expansion is $(1-x)^{-1}=1+x+x^2$ Note that the ...
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1answer
76 views

How do electrons travel through nodes

I understand this is a basic question, but I'm having such a hard time wrapping my head around it. I'm trying to avoid thinking about it as an actual "particle" but as a wave, but that confuses me ...
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1answer
30 views

The Van Der Waals Equation - High T and High $V_m$

This one is for my physical chemistry homework and I'm having trouble finding the answer. At high temperatures the Van Der Waals equation has the form $$P\approx\frac{RT}{V_M-b}$$ What would ...
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1answer
31 views

Why does steel wool catch fire when rubbed with a battery?

I was watching an episode of Man vs Wild where steel wool was rubbed with phone battery. To my surprise, the wool caught fire. What is the reason for this?
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1answer
19 views

Is sign convention for delta H and enthapy change of a solution different?

I have got some confusion . In the Ncert Chemistry Tb , it is given in bold that $\Delta H$ is negative for exothermic reactions which evolve heat during the reaction and $\Delta H$ is positive for ...
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24 views

What are the uses of a mixture of chloroform and N2 gas?

What are the uses of a mixture of chloroform and $\ce{N2}$ gas? Also, what are the uses of a mixture of camphor and $\ce{N2}$ gas?
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16 views

What is the partial pressure of Oxygen in air? [closed]

Oxygen comprises approximately $21\%$ of the air by volume. Calculate the partial pressure, in $\mathrm{kPa}$, of oxygen in $1.0~\mathrm{L}$ of air at SATP What Volume would the same ...
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0answers
18 views

Book recommendations for protein structure refinement

I’m an undergraduate Chemistry student and I’m currently writing my dissertation about semi-empirical methods, particularly PM7, applied to protein structure refinement from X-ray structure. Could you ...
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1answer
58 views

Which is the bigger ion, F- or O-?

Well, according to the proton-electron ratio $\ce{O-}$ should be bigger than $\ce{F-}$ What about the charge/electron density in $\ce{F}$? Will it not affect the size of the atom of $\ce{F-}$?
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0answers
29 views

What is the formula for migration rate of DNA in agarose gel electrophoresis?

Let's consider a typical agarose gel electrophoresis experiment. An appropriate quantity (not so much that it is overloaded, but not so little that it cannot be visualized) of linear DNA pieces with ...
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2answers
106 views

Why is carbon monoxide the product in reactions that produce high flame temperatures?

I was looking at substances that produce the highest flame temperatures upon combustion. I note that the equations for combustion are producing carbon monoxide rather than carbon dioxide. $\ce{(CN)2 ...
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1answer
61 views

Rates of reaction

Assume a reaction is of second order kinetics and that the rate constant is k. The differential rate equation is given by: A+B->Products -dCa/dt = kCaCb Show that the general expression of ...
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1answer
39 views

Why does hand sanitizer leave your skin feeling cool?

I noticed, and perhaps many others have too, that the application of hand sanitizer (mainly ethanol), leaves one's hands feeling rather chilly after application. What is responsible for this ...
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0answers
37 views

Thermodynamic dependency of the rate of reaction

On one hand, the larger is the reduction potential of the chemical reaction and the smaller is its activation energy the larger would be the rate of reaction, on the other hand the rate of a reaction ...
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0answers
11 views

Dissolving Time Function for Concrete

So I was just exploring some ideas on my own and am having trouble analytically solving the following: Let $D(n,m,T)$ be the time it takes to dissolve an n x n x n cube of concrete in m molar HcL at ...
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2answers
90 views

Determining if reaction is endothermic or exothermic using equilbrium constant

For the following reaction: $$W_{(s)}+4\,Br_{(g)}\rightleftharpoons WBr_{4(g)}$$ At 900 K, $K_{p}=100$ and at 2800 K, $K_{p}=5$. At higher temperatures, the equilibrium has shifted towards the ...
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1answer
14 views

Addition of combined gas law constant

There are two containers connected to each other but separated by a cork. If container(1) has a gas $G_1$ at a volume $V_1$, pressure $P_1$ and temperature $T_1$ and similarly in container(2) there ...
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1answer
29 views

How does the vacuum in atoms persist?

From very elementary chemistry I understand that atoms are mostly empty space, with a few tiny little objects whizzing around. There must then be a vacuum in between these particles. I always thought ...
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31 views

Why is the equilibrium constant dependent only on the temperature? [duplicate]

Is it because of the Clausius Clapeyron equation or the Arrhenius equation or Van't Hoff equation or Le Chatelier's Principle just some theoretical explanation? Also it involves $\Delta H,\Delta G$, ...
2
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1answer
71 views

The difference between heat of reaction at constant pressure and that at constant volume

If supposing the kp value of a reaction is 10 Atm at 300K and 4atm at 400K. Then how can we say that the difference between the heat of reaction at constant pressure and that at constant volume is RT ...
3
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1answer
113 views

What are the standard math prerequisites for physical chemistry?

I'm currently a chemistry major and I know that physical chemistry requires lots of calculus. Which mathematics courses should I take so that I am well prepared for my physical chemistry courses? ...
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2answers
110 views

What is the cause for thermodynamic reversible and irreversible process?

My book defines Thermodynamic irreversible process is defined as the process in which the changes take place rapidly, instead of occurring in successive stages with infinitesimal changes in ...
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2answers
61 views

Differences between chemical physics and physical chemistry?

What makes these two seemingly identical topics separate? What does each field more focus on, like do chemical physics researchers study more the atomic/molecular interactions while the physical ...
3
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1answer
86 views

Can a mixture of water miscible solvent and water be separated by fractional freezing on a dry ice bath?

If a mixture of water with acetone, methanol, ethanol, or other water miscible solvent, is cooled below 0 degrees, would the water freeze and aggregate out as ice, separating out of the mixture. Or ...
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1answer
35 views

How does the Freezing Point fall in a solution?

It is known that addition of a non-volatile solute to a volatile solvent(liquid) to give a solution reduces the Vapour Pressure of the solution (well solvent actually as only solvent is volatile). ...
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1answer
46 views

Which one, Mulliken charge distribution and NBO, is more reliable?

Sometimes the Mulliken and NBO turn out to be so different that I can't decide which one I can trust. I've heard that Mulliken is inaccurate, but is NBO always accurate? And should I use Gaussian or ...
3
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1answer
42 views

Can a solid and liquid be miscible?

To be specific, what I mean is: is the following situation possible? At given temperature T, there are two substances, X and Y, such that pure X is a solid, pure Y is a liquid, and X and Y mix to form ...
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1answer
24 views

Applying the Le chateliers principle

I am an issue understanding the changes that take place when we decrease the pressure of a reaction. I have understood that when we increase the pressure the side having more number of moles wants ...
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1answer
88 views

Problems with thermodynamic derivatives

How is the following true? $$\left ( \frac{∂S}{∂P} \right )_{T}=\frac{-C_{P}}{T}\left ( \frac{∂T}{∂P} \right )_{S}$$ I know that $$C_{P}=T\left ( \frac{∂S}{∂T} \right )_{P}$$ which means the ...
3
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1answer
43 views

Residual stress in polymer coatings

A paper talks about the residual stress when coating polymers. It says that residual stress is the sum of the "heat stress" (due to the difference in thermal expansion coefficients) and the "shrinkage ...
4
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1answer
52 views

Chemical equilibrium-reaction of change in pressure problem

I am having a problem in the following question. Ammonium carbamate dissociates as shown below. $$\ce{NH2COONH4_{(s)} -> 2NH3_{(g)} + CO2_{(g)}}$$ In a closed vessel containing ammonium ...
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1answer
48 views

What properties does a solvent with a high dielectric constant have?

My professor commented that water has a higher dielectric constant than alcohol. Okay, but on what basis? He didn't elaborate; he asked us which one seemed "more electric" and most answered water. ...
2
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1answer
64 views

Why is the equilibrium constant given in litre per mole?

At $800\:\mathrm{K}$ a reaction mixture contained $0.5\:\mathrm{mol}$ of $\ce{SO2}$, $0.12\:\mathrm{mol}$ of $\ce{O2}$ and $5\:\mathrm{mol}$ of $\ce{SO3}$ at equilibrium. $K_c$ for the equilibrium ...
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1answer
48 views

Auto ionization of water and evaporation of water

I know that the heating of water drives the auto ionization of water. It also drives the evaporation of water. My question is where do the ions go as the water evaporates as it is heated up. Ions ...
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1answer
40 views

If dark surfaces absorb/store more light/energy than light surfaces, then does dark skin, on average, store energy from light most efficiently?

If darker surfaces absorb/store more light/energy per square inch than light surfaces, then does dark skin, on average, store energy more efficiently than light skin? (edited).
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1answer
110 views

Explaining Ionization to kids

I have a quest to explain a physical, chemical theory to kids of age 8-12. The topic is "Ionization". We all understand from early experiments of Physics and Chemistry (the Millikan oil drop ...
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2answers
74 views

Peroxide Linkages

Why are peroxide linkages generally weak? Is it due to Coulombic repulsions? I can't see how placing two oxygens with high degrees of partial negative character next to each other is a good thing in ...
4
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2answers
47 views

Nitrogen dioxide dimerization

$\ce{NO}$ can't dimerize and that is explained because the free electron is in an antibonding orbital. The same is true for $\ce{NO2}$, but it can dimerize, how?
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1answer
80 views

Why can't light pass through a gold foil, but alpha particles can?

Rutherfords experiment showed that most of the alpha particles passed through a thin gold foil undeflected. So why can't light pass through the foil, which is supposedly thinner than the heavy alpha ...
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2answers
87 views

How can two electrons lie together in an orbital?

Two electron of opposite spin can lie in a single orbital.. But what about the electron-electron repulsion. Okay! I got that the nuclear charge rather the large Z-effective overcome this repulsion by ...
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2answers
158 views

Difference between actual position of electron and Radial Distribution Probability

Its known that the radius of maximum probability of 2s orbitals is more than that of 2p orbitals. It means that the maximum probability of finding an electron in an 2s is further away from electron ...
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2answers
24 views

How to figure out which phase in The Phase Diagram will have more density?

If I am given Phase Diagram and asked to determine which phase will have more density? What to consider to solve this kind of questions is it about thr area that each phase occupies? the more area a ...
2
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1answer
25 views

Proteins and their solubility

I have 2 statements , and i am not sure, whether they are true or false. Proteins like albumin and haemoglobin are insoluble in water (in my view , almost all proteins are soluble- so this is a ...
3
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1answer
22 views

What is the Solubility of Common Noble Gases in Concentrated Phosphoric Acid, 85% w/v?

By Henry's Law, the concentration of a dissolving gas in a liquid is proportional to the partial pressure of that gas in contact with the liquid , mathematically, $ p = k_H c$, where $p$ is the ...
2
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1answer
32 views

Synthetical formation of diamonds

As everyone knows a diamond won't last forever. It will eventually turn into a graphite over a long period of time, as the free energy of graphite is lower than that of diamond, hence making the ...