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.
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Using Dalton's law of partial pressures
A container of volume $\pu{4.0 L}$ contains nitrogen at $\pu{25 °C}$ and $\pu{803 kPa}.$ This container is connected by a valve to another container of volume $\pu{10.0 L}$ that contains argon at $\pu{...
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Chemical reactions with a room-scale cooling effect
Are there chemical reactions that could cool down an average sized room by a noticeable amount (say 5 °C)?
I would like to investigate if it is possible to have a situation where I can mix 2 ...
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Is ash fireproof?
At high temperatures (almost) everything burns to ash. Is ash 'fireproof'?
Is further combustion of ash possible for example by combining with hydrogen, oxygen, etc?
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Understanding dissolution of CO₂ in Selexol and Rectisol
I'm trying to understand pre-combusiton carbon capture processes as described in this presentation.
I'm told that solvents such as chilled methanol ($\ce{CH3OH}$) and dimethyl ethers of ...
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Is there a similar characteristic of the lanthanide contraction in the other transition metal groups?
Basically, does the lanthanide contraction also occur with the 4d, 6d groups as well? I am at a lack of understanding in this topic, I am just wondering what specific elements does this jump in a ...
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Calculating the heat capacity of a calorimeter
I've been struggling with this problem that I can't seem to figure out. I think I know how to solve it but I think there's missing information.
The combustion of 1 mole of glucose $\ce{C6H12O6}$ ...
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What is the 'ancestral term' in the LS coupling scheme?
On the physics.nist.gov site: http://physics.nist.gov/Pubs/AtSpec/node06.html
The table titled "Atomic structural hierarchy in LS coupling and names for the groups of all transitions between ...
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multielectron spin-orbit coupling and energy level
For multi-electron atoms for which the Hamiltonian (including the spin-orbit coupling) reads
$$H=\sum_i T_i-Z\sum_i V_i+\sum_i V_i^{\text{s.o.}}+\sum_{i>j}V_{ij}$$
The $T_i$ are the kinetic ...
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Can molecules diffuse upstream when emptying a cup of tea?
I was drinking some tea, and I randomly decided to pour some into the toilet in an unbroken stream; can particles travel "upstream" quickly enough to reach the mug of tea? How fast can diffusion occur ...
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Is there any scenario in which the size of a molecule increases due to an increase in temperature?
Take an ice cube for example. Heat is applied in a closed container until it is vaporized completely. Will the molecule's size be larger (on average)? Is there a substance that you know of that has ...
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deduce chemical properties of a compound from elements
If we know the properties of two elements e.g Oxygen and Hydrogen.
We know the following properties
sound speed
boiling point
melting point
refractive index
etc.
given that information, is it ...
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Moment of inertia for a triatomic molecule
What does the moment of inertia for a molecule mean? How is it useful? Most importantly, how would I go about solving it for a triatomic molecule?
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What is 'autogenous pressure'?
Compound 1 was hydrothermally synthesized under autogenous pressure[1]
I've seen this term used a few times, but with no real explanation of what it means forthcoming. I suspect it refers to the ...
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Is there a simple way to get the circular dichroism of a molecule from its structure?
Are there any heuristics to get the relative absorbtion of left and right circularly polarized light by a molecule from its molecular structure? Is it even possible to predict which polarization is ...
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Hierarchy of electronic wavefunctions
The previous question contained too much unnecessary information and was edited.
I am wondering about the "hierarchy" of wavefunctions. If one can combine atomic orbitals (AO) into molecular orbitals ...
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Electrical conductivity of graphite
On this Wikipedia page, the electrical conductivity of various materials are given in the third column ($\sigma \text{ (S/m) at 20}^\circ \text{C}$). I am interested in the entry for Carbon (graphite)...
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What is the difference between temperature and thermodynamic temperature?
My course book says that kelvin is the unit of thermodynamic temperature, then what is the difference between temperature and thermodynamic temperature.
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Deliquescence/efflorescence: How can I convert between salt concentration and RH?
I am looking at two phase diagrams, one has axes of $T$ and $\%\ce{MgClO4}$ in a $\ce{H2O-MgClO4}$ mix, and the other has axes of $T$ and relative humidity. The authors of the second phase diagram say ...
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Why does oxygen not condense onto open dewers of liquid nitrogen?
I had a discussion with my supervisor today after I was a touch careless pumping down a flask with a liquid nitrogen cold trap attached. I checked, and there are reports of explosions after running ...
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Where can I obtain tables of P-V-T/compression factor data?
Some recent research I'm dealing with has required me to look for tables of experimental pressure/volume/temperature values (equivalently, a table of compressibility/compression factors in terms of ...
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Energy-efficiency aside, what are the chemical constraints on CO₂ capture and methanation?
Synthesising $\ce {CH4}$ from air and water (in a non-biological process) has been proposed as one form of energy storage. What are the chemical constraints at play here? That is to say, what sort of ...
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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 ...
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What is antisymmetric exchange? What is J-strain? Where does it come from?
I'm reading a paper1 by Sanakis, et al. that characterises the magnetic coupling in the $\ce{Fe3S4}$ clusters present in bacterial ferredoxin II and beef heart aconitase as arising through something ...
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How to calculate the equilibration time of two connected chambers of salt solution, initially at different concentrations?
I am trying to build a system of two connected chambers, one of which is also connected to a cuvette, so I can perform a spectrometry experiment with different concentrations of $\ce{KNO3}$ solution. ...
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What is a rigorous definition of gas volume, and how is the Van der Waals equation derived?
I am confused about the justification for the corrections to the ideal gas law in the Van der Waals equation: $$p=\frac{nRT}{V-nb}-a\left(\frac{n}{V}\right)^2$$
I understand that the equation ...
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Hanging a spoon on the face
Well, I have seen many comical acts where people balance a spoon (or a fork) on different parts of the face like on the tip of the nose, forehead etc.
The do this by blowing moist air (see below) and ...
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Choice of doping elements in semiconductors
In a typical semiconducting material, we start with silicon (group IV) and introduce atoms of group V or group III depending on whether we are constructing an n- or p-type semiconductor respectively.
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How does dimethylsulfoxide serve as a cryoprotectant?
In cell culture, dimethylsulfoxide (DMSO) is added to prevent the formation of ice crystals which may lyse the cells. Exactly how does dimethylsulfoxide act as a cryoprotectant?
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Can an atom have more than 8 valence electrons? If not, why is 8 the limit?
According to some chemistry textbooks, the maximum number of valence electrons for an atom is 8, but the reason for this is not explained.
So, can an atom have more than 8 valence electrons?
If ...
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Are there any examples of nuclear spin isomers having consequences for chemical reactivity?
Ortho- and parahydrogen are two forms of the $\ce{H2}$ molecule that are distinguished by their pairing or antipairing of nuclear spins, giving rise to metastable singlet (ortho-) and triplet (para-) ...
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what kind of suspension liquid should be used with ferrofluid (so it does not stain the glass)
Please take a look at the following video:
I am working on a new project, and I need to find whats the best liquid to hold ferrofluid inside the glass (or maybe even plastic) container, so that ...
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What's the difference between precipitate and turbidity?
In many tests for various radicals, a "<color> precipitate" or "<color> turbidity" is mentioned. For example, lead ...
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Why are equations of state for a non-ideal gas so elusive?
The ideal gas equation (daresay "law") is a fascinating combination of the work of dozens of scientists over a long period of time.
I encountered Van der Waals interpretation for non-ideal gases ...
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Why does ice cream make soda fizz?
I've noticed that adding a chunk of ice cream to soda makes the soda fizz slightly near the soda-ice cream interface. I thought it was a physical effect due to the temperature, but adding ice has no ...
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When simulating spectral line broadening, which convolution is preferred?
Many computational chemistry packages permit the calculation of vibrational and electronic spectra. These spectra are obtained as a set of discrete eigenvalues however they are often convolved with ...
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Can dissolution reactions be endothermic?
Is it possible for a dissolution reaction of the form
$$\ce{X(s) ->[solvent] X (solv)}$$
or
$$\ce{M_mX_x (s) ->[solvent] m M^x+ (solv) + x X^m- (solv)}$$
to be endothermic, i.e. $\Delta_\...
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Gas chromatography/mass spectrometry: Can I use peak ratios and molecular mass to derive quantity?
Can derive the quantity of a substance from a GC/MS report if I know:
the ratio to another substance in the data,
the quantity of that second substance, and
the molecular mass of both substances.
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How does conductivity work for non-redoxed ions?
Related (very similar, but here I want a mechanism) https://physics.stackexchange.com/q/21827/7433
By the Kohlrausch law, all ions contribute to the conductivity of an electrolyte.
Now, as I ...
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What are the major factors that influence LogP
The partition coefficient is a very useful metric in characterizing compounds particularly drugs. What chemical properties influence that partitioning? Are chemical moieties additive in their LogP? ...
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A quick method for separating liquids?
I'm looking for a way to take 3 separate liquids (liquids which function as paint -- they will all be different colors), put them together into a container, and then rapidly separate them back to ...
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General rules for deciding volatility
Given an organic compound, is there any way to decide if it is volatile (or compare volatility--everything is volatile in the end)?
Volatility is due to the tendency to evaporate. The conclusion I ...
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Why is distillation not a viable way to separate ammonia from water?
Since the steam pressure of ammonia is higher than that of water, I would expect distillation to be a reasonable way of separating a mixture of both.
However, in industrial applications known to me ...
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