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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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Melting and boiling point

In a temperature range in the vicinity of the melting point of $\ce{TaBr5}$ the following relationships are valid for the vapor pressure: $\log P=18814-7518T^{-1}$, for the liquid phase $\...
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Topic in Salt hydrolysis that I couldn't understand

Salts can be made up of all combination S of ( SA ,WA) and (SB , WB) I understand how to deal with salts of strong acids with both strong and weak bases and also of strong bases with weak and strong ...
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75 views

Reversible and irreversible cyclic processes

The answer in Arihant's book is given as (b), but wouldn't (c) be correct as well? This is a question of IIT JAM Chemistry. A system undergoes two cyclic processes 1 and 2. Process 1 is reversible ...
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56 views

Thermodynamics of a spontaneous isothermal chemical reaction.

Which of the following is/are correct for spontaneous isothermal chemical reaction? (A) $\Delta H = 0$, because $\Delta T = 0$ (B) $\Delta S = 0$ (C) $\Delta U = 0$, because $\Delta ...
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HCl + NaCIO + Al + Fe What Happens? [closed]

So I am going to combine the following elements and chemicals for an experiment. HCl + NaCIO + Al + Fe (Hydrochloric Acid + Sodium Hypochlorite + Aluminum + Iron) I understand that hydrochloric ...
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1answer
43 views

In zero order why we don't need the coefficient of reactant in integration of rate law?

For a reaction: $\ce{aA->product}$ The rate law is $\text{Rate}=-\dfrac{\mathrm d[A]}{a\,\mathrm dt} = k$ Where: $k$ is the rate constant $[\ce{A}]$ is the concentration of the reactant $\ce{A}$...
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1answer
23 views

Work function vs ionization enthalpy [closed]

I've seen that the work function of a particular metal is always greater than its work function. Is it the case always? If so why? For example, the first ionization energy of sodium is 5.14 eV/atom(...
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1answer
37 views

Does “higher symmetry” mean any symmetry group of higher order?

What is the precise definition of a higher symmetry in group theory? I see this term scattered around, such as in Cotton's Chemical Applications of Group Theory: ...In the cyclic groups each of the ...
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1answer
107 views

Using thermodynamics to predict the acid-base character of fluoride ion in water

I was working through the end-of-chapter exercises of the acid-base chapter in Shriver's Inorganic Chemistry when I came across the following problem: 4.7. The effective proton affinity $\ce{A^{'}_{...
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29 views

Why has na 1S0 term Ag symmetry?

This question is a continuation of Molpro - Connection between atomic term symbols and system symmetry. In the Feodoran's answer I found it somehow confusing, that ${}^1S_0$ term should be totally ...
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1answer
39 views

Finding the weighted parameters of the vertex adjacency matrix for a derivative of azulene

In my last question ( Numbering in a derivative of azulene ), I asked about the numbered of a molecule in order to find the Vertex Adjacency Matrix (VAM) of the same molecule. To explain my question ...
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1answer
71 views

Molpro - Connection between atomic term symbols and system symmetry

Let's say I have a carbon atom with the electron configuration $1s^22s^22p^2$. We know, that using atomic term symbols we can describe the following states: $${}^3P_0, {}^3P_1, {}^3P_2, {}^1D_2, {}^...
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2answers
107 views

Connection of term symbols with specific microstates for atomic carbon

I'm currently studying atomic term symbols. I wanted to try it on a simple atomic carbon with the electron configuration $1s^22s^22p^2$. I know, that only open-shell electrons are involved in the ...
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0answers
27 views

How are second and third electron affinities of atoms measured?

Wikipedia data page on electron affinities shows second and third electron affinities. Of course, they are negative, because one tries to attach electron to anion. But how are they measured or ...
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1answer
37 views

I need some help on this Chemistry question can any one help please!! I need to find the cost of a single atom of aluminum [closed]

A 75 ft2 roll of aluminum foil costs $3.79. A 12"x12" pieces has a mass of 1.0 g. How much does a single atom of aluminum cost, in dollars? i need to show all my work i am so lost.
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1answer
21 views

Can nuclear shielding affect relaxation time?

Can nuclear shielding affect the transverse relaxation time, i.e extend the relaxation time the more the nuclei is shielded?
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1answer
18 views

Would atomic oxygen and atomic hydrogen result in O2 and H2 only, or some H2O too? [closed]

Let's assume we have atomic oxygen and atomic hydrogen in a closed chamber, the temperature and pressure of which we're able to monitor (and control). Number of hydrogen atoms are twice that of oxygen....
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32 views

Can hydrocarbon help to split molecular hydrogen into atoms?

I am a physicist and have the following chemistry problem. When a sample is exposed to H2 (molecular hydrogen), a tiny amount of atomic hydrogen or, maybe, protons is generated. Extremely small ...
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1answer
39 views

Why are reactions with higher activation energy more sensitive to temperature?

In the above picture it is stated clearly, with an example, that the more the Ea of a rxn the more it's sensitive to temperature, and hence even a small change in temperature in a reaction with high ...
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22 views

Rate equation of a radical

Consider the following elementary reaction mechanism where both the forward and reverse reaction mechanism are important $$\ce{CO + O2<->[1] CO2 + O}$$ $$\ce{O + H2O<->[2] OH + OH}$$ ...
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NMR sweeping magnetic field

I am currently doing a experiment in the lab which is using a continuous wave NMR, by sweeping the magnetic field, and I am having trouble understanding how the theory works for this type of ...
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1answer
53 views

How to derive rate law expression for inversion of sucrose with changing pH?

I came across a question worded as follows- "The inversion of cane sugar proceeds with half life of 50 minutes at pH=5 at any concentration of sugar. However, if the pH=6, the half life changes to 500 ...
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1answer
24 views

Why are there distortions in electron cloud in molecules? How does increase surface area amplify these distortions?

In the physical properties of hydrocarbons,it is said that branched hydrocarbons have relatively less boiling point than it's linear form. From what I have learnt is that it is due to the increase in ...
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2answers
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Why is ammonia still considered polar despite undergoing rapid inversion?

Here it is stated that a molecule with a rotation axis cannot have dipole moment perpendicular to the axis, as any dipole moment would be changed upon rotation about this axis (which preserves the ...
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Effect of redefining Avogadro's constant and kilogram on molar mass

Avogadro's constant $N_A$ is defined as the number of constituent particles (usually atoms or molecules) contained in the amount of substance given by one mole. The value of Avogadro's constant $N_A$ ...
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1answer
46 views

Equation for the equilibrium constant for the hydration of carbonyls using UV spectroscopy

I was looking through the literature when I found this source: https://pubs.rsc.org/En/content/articlepdf/1967/tf/tf9676302131 Which states that the equilibrium constant Khyd is: Khyd = $\frac{[...
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2answers
33 views

The mechanism of the reaction between 2-chloroethanol and hydroxyl ions in aqueous solution

The mechanism of the reaction between 2-chloroethanol ($\ce{CH2ClCH2OH}$) and hydroxyl ions in aqueous solution forming ethylene oxide ($\ce{CH2CH2)O}$ probably contemplates two steps: $\ce{...
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0answers
28 views

structure information form IR and Raman spectra? [closed]

Is it possible to gain the idea of full molecular structure from IR or Raman spectroscopy?
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0answers
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How does mesh size of Barium Chloride affect sulfate results via turbidimetric method?

I am analyzing sulfate using Standard Methods 4500 $\ce{SO4 ^2-}$ E (turbidimetric method) using $\ce{BaCl2}$ and measuring %T at 420 nm. In the past, we used an appropriate 20-30 mesh size for the $\...
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1answer
61 views

Depression of freezing point [closed]

Recently, I learnt that by adding a non-volatile solute to a solvent, the vapour pressure of the solution is decreased and consequently its boiling point. Also consider the definition of the ...
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0answers
53 views

Significance of this unusual matrix element

Recently, I was solving some questions on Rigid Rotor. I found this question very amusing. Evaluate the integral i) <$Y_{l,m+2}$ | $L_{x}^{2}$ | $Y_{l,m}$ > I evaluated it, found that the value ...
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How to calculate relations among thermodynamic quantities

I'm trying to learn how to calculate the many relations that exist in thermodynamic. Like for example $$ \left(\frac{\partial U}{\partial S}\right)_V $$ or $$ \left(\frac{\partial S}{\partial T}\...
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Chemistry: What's the difference between “binding energy” and “ionization energy”?

In respect to PhotoElectron Spectroscopy (PES), we are analyzing graphs with "binding energy (MegaJoules)" on the x-axis, and with "relative number of electrons" on the y-axis. I have also seen the x-...
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1answer
30 views

How to correctly apply Law of mass action

While studying ionic equilibrium I came across a relation between solubility and solubility product for ternary salt. This is what was written in my book. Let the solubility of ternary salt $AB_2$ ...
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1answer
54 views

Interpretation of H as T goes to absolute zero

Euler's identity for the enthalpy states that (for a single component and phase) $ H = TS + \mu N$ What are the implications of this expression in the context of the third law of thermodynamics (...
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1answer
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Celsius to Kelvin [closed]

A temperature conversion question asks the following: "The temperature of a sample of a substance changes from 10°C to 20°C. How many Kelvin degrees does the temperature change?" The correct answer ...
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AFM of Smooth Amorphous Carbon

I have been having trouble getting decent resolution images and clear data of smooth amorphous carbon thin films prepared by RF bias assisted vacuum deposition. I was using a DLC tip in tapping mode ...
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1answer
25 views

Fishes and Heater

I had an aquarium for about an year and this week my mum just installed a heater in it. On asking, she told me that fishes would die in cold water. But from Henry's Law, isn't it that more oxygen ...
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Why does wood burn but not sugar?

Fundamentally, they're both carbohydrates, although the cellulose in wood is essentially polymerized glucose, which combined with its isomer fructose forms sucrose. So why does wood readily burn ...
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2answers
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Francium has isotopes so how can its atomic mass be a whole number?

Why do francium, radon, radium, and actinium have whole numbers for average atomic mass even though they have isotopes? But then elements like beryllium, fluorine, and sodium are listed as having no ...
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1answer
42 views

Does gravity , say of another planet, affect the atomic mass and therefore the molar mass of water? [closed]

Does gravity , say of another planet, affect the atomic mass of elements and therefore the molar mass of water?
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1answer
90 views

Is graphite a better lubricant on the Moon than on the Earth? [closed]

My book says that it is a better lubricant on the Moon because of absence of gravitational pull on the Moon. However, I also read that it's lubricant nature is because of a film of moisture or gas ...
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1answer
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Would a red or a white light be more effective at charging a calculator battery?

White light contains the entire visible spectrum including red light, so would it be more effective at charging a battery?
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37 views

Feasibility of application of Boyle's law in the case of varying number of moles [closed]

While reading up on ideal gases and the Boyle's law, I encountered a question in my textbook wherein a balloon was being filled with helium (assumed to be ideal) till it was just about to burst. The ...
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0answers
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Benzophenone Ketyl color origin

I was recently preparing the benzophenone ketyl radical by reacting it with sodium in toluene. Although this compound is really well known and it seems somewhat obvious and accepted in literature that ...
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1answer
137 views

Lattice energy of NaCl and MgCl

In an exam paper it says that the lattice energy of NaCl is more exothermic than MgCl as the Na+ cation has a smaller ionic radius than Mg+. Here are the resources given: What is the reasoning for ...
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1answer
32 views

Can an uncharged particle pass through a molecular bond? [closed]

Do particles ever pass through or interact with the molecular bond? Is there a physical size limit? What happens to the atoms and the particle and does this ever happen in real life?
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1answer
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How do you figure out fuel specific impulse non-experimentally?

Simple question, probably very complicated answer: Without building a test engine/rocket and finding out experimentally, that is to say, based on chemical characteristics alone, how can one compute ...
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1answer
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Why it the electron affinity of beryllium is greater than nitrogen? [closed]

As we know that fully filled electronic configuration is more stable than half filled electronic configuration, so in my opinion beryllium's electron affinity should be less than nitrogen's. Is my ...
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1answer
54 views

Effective attenuation coefficient for polychromatic light

The Beer-Lambert law gives the optical intensity of collimated light as a function of depth $z$ as: $$I(z)=I_{0}\mathrm e^{-\gamma z},$$ where $\gamma = \alpha + \beta$ is the wavelength-dependent ...