Questions tagged [physical-chemistry]

The study of chemical systems using the laws and concepts of physics. This usually requires the techniques of thermodynamics, statistical mechanics and quantum mechanics.

Filter by
Sorted by
Tagged with
10
votes
2answers
368 views

How can enzyme/substrate reactions that adhere (largely) to quantum theory also require 'Newtonian' consideration of gravity?

I'd just like to ask for a little clarification here due to confusion from interdisciplinary studies. I'm currently reading the 1976 paper related to the recent 2013 Nobel Prize for Chemistry, by 2 ...
5
votes
1answer
16k views

Determine concentration Using Beer's law

How do you determine concentration of a sample using wavelength and absorbency? Say our wavelength for a sample of Red 40 is 508.50 nm and absorbance is 0.283 when we use 6ml water and 4 ml Red 40. ...
2
votes
2answers
363 views

Why do puffed rice stick to wet hands?

My mom gave puffed rice to eat, I had quite wet hands. I saw that, each puffed rice pieces started hanging to the hand, when I brought my hand in contact with them. I thought about electrostatics ...
5
votes
1answer
3k views

Why do liquid crystal displays (LCDs) visually distort under pressure?

A venerable question, as old as LCDs themselves. I assume it has something to do with pressure-induced changes in the path length across the display, but that's just a guess. Of particular interest to ...
0
votes
2answers
69 views

A function for getting the nuclide's nuclear binding energy?

Is there a function $f(A)$ or $f(Z, A)$ that gets the energy of nuclear binding of one nuclide in atom? Or other way to get it? My chemistry book says only to get it from the chart which is very ...
1
vote
1answer
958 views

The molar mass of aluminum by measuring the amount of hydrogen gas liberated when a sample of aluminum is treated with excess hydrochloric acid

This experiment involves the determination of the molar mass of aluminum by measuring the amount of hydrogen gas liberated when a sample of aluminum is treated with excess hydrochloric acid. In the ...
3
votes
1answer
729 views

What does HTO decay into?

I'm aware that tritium undergoes beta decay forming Helium-3. But in the case of HTO, what does it decay into? I don't suppose it decays into HeHO.
0
votes
1answer
1k views

How do point defects in a crystal relate to Entropy?

I am interested in Non-Stoichiometry and how it relates to crystal structures; In particular I wish to learn about surfaces of metal oxides. I am aware that point defects in such crystals are a result ...
1
vote
1answer
564 views

What is the solid crud that appears inside my kettle?

Almost every share-house I've lived in has had some nasty looking solids collecting inside. I always regret looking inside the kettle because a cup of tea never tastes quite as good after you've seen ...
1
vote
0answers
120 views

How effectively bound Na2CO3 and BaCL2 water

How fast does $\ce{BaCl2}$ bind water from its surroundings, becoming a hydrate, compared with same process with $\ce{Na2CO3}$?
3
votes
0answers
51 views

What Does the Equilibrium Constant represent? [duplicate]

If the Equilibrium constant stands for the extent of reaction at equilibrium, whether more of forward or backward reaction is taking place, then why is it not affected by factors like concentration of ...
4
votes
1answer
173 views

Solvated solids

I have a very basic question concerning solvation. If a solid (solute) was dissolved in a liquid (solvent), is the solute still in the solid state? or does it convert into another state of matter when ...
4
votes
2answers
470 views

Gold nanoparticles in a water/oil environment

I am currently investigating the assembly of gold nanoparticles in a mixture of water and oil. The thing is the following: If we have gold nanoparticles (35nm diameter) dispersed in water and we put ...
3
votes
1answer
961 views

What is advantage of creating elements that disappear in a flash?

More than dozen of heavy elements of periodic table do not occur naturally but are prepared artificially at nuclear reactors.. These elements are said to disappear in a flash.. So, why invest lot of ...
3
votes
1answer
311 views

Superheating metal alloy above solidus

Is it possible to heat a material above its solidus without melting occurring? More specifically, at a heating rate of approximately 200K/s, will a metal alloy exhibit superheating and if so by what ...
1
vote
2answers
907 views

Why is water evaporation not more commonly used to cool buildings [closed]

Water has a very high heat of vaporization (2260 kJ per kg). Why not just gradually sprinkle water on your roof to keep the building cool in opposed to using air conditioners? It wouldn't take much ...
5
votes
1answer
2k views

Which elements have no liquid form at atmospheric pressure?

Carbon has no liquid form at atmospheric pressure. Is this unique amongst naturally occurring elements? The more interesting and vague question is, is this property somehow important or related to ...
0
votes
1answer
343 views

Ratio of concentrations

I'm studying for my chemistry final and having a hard time with this question on one of the practice exams. Here's the question: At $20$ degreees Celsius, Henry's Law constant for Ar is half of that ...
1
vote
1answer
253 views

Storing kinetic energy in bonds

Let's assume a setup with a static linear molecule with three identical atoms connected by bonds and a single atom, identical to the other three, being shot at the molecule. Let's also assume that ...
11
votes
1answer
194 views

Why search new elements?

I've read this today. From the little I know, they discover new elements by bombarding some atoms in particle accelerators (I guess) and these new elements last a few miliseconds. So what's the ...
5
votes
1answer
386 views

Thermodynamics behind Deliquescence?

The phenomenon of deliquescence wherein a water soluble substance absorbs water from atmosphere and dissolve in it forming a saturated solution, has thermodynamic roots. I have read the fact that the ...
4
votes
2answers
3k views

Wave function for particle in a infinite well located at -L and +L

The wave function for a particle in a infinite potential well located at $0$ and $L$ is $$\psi_n=\sqrt{\frac2L}\sin\frac{n\pi x}L$$ I want to find our wave function for the same situation where the ...
7
votes
1answer
275 views

Negative retention for chloride in hydrolysate filtration

I tried to fractionate proteins as a function of their size with an ultrafiltration membrane. I observed a higher concentration of chloride in my permeate than in my feed or retentate. The proteins do ...
2
votes
1answer
3k views

Why doesn't diffusion take place between immiscible liquids?

If we take a test-tube of bromine and invert an upside-down test tube of air on top of it, it'll diffuse with the air, until the bromine is thoroughly 'mixed' with the air in both test tubes. But why ...
2
votes
1answer
80 views

Reaction with carbon

Usually maximum time we see then after cooking by gas there is no black spot on the pot. But continually burning can affect the pot surface and makes black powder. My question is: What is the ...
2
votes
1answer
542 views

Salt Hydrolysis

Referring to this, when "hydrolysis of a salt" is its reaction with water: How is it that both the cation and anion of the salt are reacting in an equal amount with water? To state this specifically ...
5
votes
2answers
2k views

How to determine a Reynolds number for mixture of 2 liquids

I'm experimenting with synthesis in microreactors and I'm using 2 reactants. I'd like to estimate the Reynolds number of the flow containing two miscible fluids. I have the values of their properties (...
1
vote
1answer
597 views

Electrochemical Cell

Now in an electrochemical cell , we make use of the fact that whenever there is a potential drop , electrons will flow from lower to higher potential as for a potential drop , there must be an ...
4
votes
1answer
922 views

Effect of vibration on wine quality

Most people that have ever visited a viticulteur (winemaker) will know that it is common wisdom that vibrations are bad for the wine quality. When I was just a kid the winemaker always told me that we ...
6
votes
2answers
2k views

Bonding and anti-bonding orbitals in the light of time-dependent Schrödinger equation?

In organic chemistry, people draw 2p orbitals like this: and then they explain how the orbitals combine to non-bonding (π*) or bonding (π) molecular orbitals, like this: depending on whether the ...
1
vote
0answers
34 views

Chemical Equilibrium - Why does changing the temperature shift the equilibrium? [duplicate]

I know that raising the temperature in a reversible chemical reaction causes the equilibrium to shift to the endothermic side. I know that $\Delta G = \Delta H - T \Delta S$ but I don't know how to ...
1
vote
3answers
2k views

On the scale of stuff with a pH

I am a confused (and somewhat anal retentive) non-chemist who is trying to understand what pH is. I have come to understand it is a measure of acidity, but I have not yet figured out what that means ...
9
votes
2answers
475 views

Did Mendeleev predict the existence of neutrinos?

According to this Wikipedia page, Mendeleev originally believed that the inert gases belonged in Group 0 (to the left of the alkali metals). Thus, helium would be placed in the second period to the ...
2
votes
1answer
2k views

How do I calculate partial pressure here?

I need some help with partial pressures of reactions for a fuel cell project. The overall reaction for a fuel cell is $$\ce{H_{2} +\frac{1}{2}O_{2}->H_{2}O}$$ Which means that the mole fraction ...
1
vote
2answers
171 views

Lewis model and modern physics

Electron affinity of chlorine = -349 kJ per mole. And, first ionization energy of sodium = 496 kJ per mole while energy required for combining= 147 kJ per mole. Isn't it a contradiction against ...
1
vote
1answer
3k views

How do I know if concentration of Ammonia affected my absorbency measurements?

This is for determination of copper in a penny Lab. After making standard solutions we made a solution with a penny, dissolving it in nitric acid and adding ammonium hydroxide to form a more ...
1
vote
2answers
608 views

What are the main axis of research in Chemistry? [closed]

I would like to know what are the main problems currently studied in Chemistry. For some reason, it seems that there is far less vulgarisation in chemistry than the other fields, and it's hard to ...
4
votes
1answer
472 views

Why do aqueous solutions always have to be electrically neutral?

I was reviewing some analytical chemistry and stumbled upon a section that explained the imperfection of using a salt bridge. It said that the using dissimilar ions is a problem because in, for ...
2
votes
1answer
136 views

Are there any free electrons in metal vapor?

Metals contain free moving electrons, in both the solid and liquid state. Does this happen when it is in vapor form?
2
votes
2answers
12k views

When is it okay to use $Q=mc\Delta T$, is this equation only for calorimetry questions?

When is it okay to use $Q=mc\Delta T$, is the equation only for calorimetry questions? When a question talks about heat how do I know if i'm measuring $\Delta H$ or Q?
1
vote
0answers
354 views

Polar group strong dipole effect molecular axis

There are some fundamental charactaristics of liquid crystal. One of them is that all liquid crystals are organic compounds and at one side of their long molecular foundation there exists a polar ...
6
votes
2answers
523 views

Measuring Thermodynamic Stability

We can predict whether a reaction can occur spontaneously by calculating the change in Gibbs' free energy. I was just wondering whether there is any general measure of the thermodynamic stability of ...
3
votes
1answer
3k views

Application of the Arrhenius equation to a parallel reaction

I'm struggling with this homework question: "For a parallel reaction A goes to B with rate constant $k_1$ and A goes to C with rate constant $k_2$, you determine that the activation energies are 71.9 ...
-3
votes
1answer
4k views

which chemical element has the lowest boiling point? [closed]

which chemical element has the lowest boiling point? Is it Helium(He) or is it Hydrogen(H)? Hydrogen is lighter than Helium.
2
votes
1answer
575 views

Solid hydrophilic transparant materials that don't dissolve in water

I am looking for hydrophilic transparant materials which are solid at room temperature and that don't dissolve in water. I need these for an experiment in which I condense droplets on a plate made out ...
14
votes
1answer
8k views

How can a group be both a good nucleophile and a good leaving group?

I'm reading about $\:\mathrm{S_N1}$ and $\:\mathrm{S_N2}$ reaction mechanisms, and I have a few questions. My book has a couple of tables, one lists a bunch of substances grouped as good, moderate ...
5
votes
1answer
135 views

$K_{eq} $ vs $K_c$

I was wondering if there was a difference between $K_{eq}$ and $K_c$. I think they both refer to the Equilibrium Constant. If I'm wrong, could you please tell me the difference between the two? Thanks!...
1
vote
1answer
120 views

Is it possible to form bubbles of ionized hydrogen and ionized oxygen under the right pressure/temperature conditions during electrolysis of water?

When we run a current through water (pure or not), $\ce{O_2}$ forms at the anode while $\ce{H_2}$ forms at the cathode. If I understand correctly, as water is already slightly ionized, $\ce{H}$'s snap ...
10
votes
1answer
4k views

How to determine which gas is more soluble

I have a chemistry homework problem that asks whether $Br_2$ or $O_2$ is more soluble in water in room temperature. However, I can't seem to find a way to figure it out, short of looking it up. Is ...
2
votes
1answer
3k views

What is the chemical composition of a Rubbermaid Roughneck container and is it feasible for me to make my own molds?

I'm looking for more information on the composition of a Rubbermaid Roughneck container. The description says "Roughneck containers are made with a durable polyethylene material for a lifetime of ...