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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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HCl + NaCIO + Al + Fe What Happens?

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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Internal energy question

Calculate the work done when $\pu{176 g}$ of $\ce{Fe}$ reacts with $\ce{HCl}$ to produce $\ce{H2}$ gas (i) in a closed fixed volume, and (ii) in an open beaker at $\pu{25.0^\circ C}$ (isothermal, $\...
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14 views

Why are dislocations thermodynamically unstable?

Dislocations are thermodynamically unstable in contrary to point defects.In this context I would like an answer for this.
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27 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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Substance dissolved in non-polar solvent, then added to polar solvent? [on hold]

What is the fate of a substance dissolved in a non-polar solvent, say ethanol or acetone, then added in small proportion, say 10% v/v, to a polar solvent such as water? The solubility of the substance ...
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2answers
16 views

Calculation of pH of mixture of strong acid and strong base [on hold]

I have been given a mixture of 150 ml of an aqueous solution of HCl (pH = 2.0) and 350 ml of an aqueous solution of NaOH (pH = 12.0). How can I calculate the pH of of the mixture?
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9 views

help with entropy and enthalpy questions [closed]

Looking over some Homework questions i'm really struggling trying to get my head around these entropy/enthalpy questions, the lecture slides are very brief and unhelpful, any help would be greatly ...
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1answer
12 views

Work function vs ionization enthalpy [closed]

Why is the work function of a particular metal always lower than its gas phase ionization enthalpy ?
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1answer
28 views

Why doesn't increasing number of photon increase the number of ejected electron? [closed]

I know that in the equation, nothing depends on the numbers of photons, but why wouldn't increasing the number of photons increase the number of ejected electron? If I use the diagram (second picture)...
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7 views

Diffusion mechanism in Microsegregation [closed]

Please explain me the process of microsegregation in case of nucleus with close reference to the diffusion mechanism that are involved at solute and solid liquid interface.A very detailed answer would ...
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0answers
8 views

The sharing of electrons in covalent bond [duplicate]

The electrons in the covalent bond are shared by atoms. However, how do these electrons ''fly''? For example, in H2O, they shared four electrons. Do they flying around the nuclear of the three atoms? ...
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22 views

Thermodynamics question: calculate the amount of heat released in the combustion [closed]

When 5 litres of a gas mixture of methane and propane is perfectly combusted at 0°C and 1 atmosphere, 16 litres of oxygen at the same temperature and pressure is consumed. The amount of heat released ...
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Setup to prove dynamic nature of equilibrium [closed]

The basic question is how is it known that chemical equilibrium reached in reversible chemical reactions is dynamic and not static? What would be the experimental setup to demonstrate the dynamic ...
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12 views

Simultaneous exuilibrium , Ph Calculations and approximation [closed]

The Question is :- 200 ml of 0.1 M H3AsO4 (given Ka1 = $10^{-3}$ , Ka2 = $10^{-7}$ Ka3 = $10^{-12}$) 50 ml of 0.4 M Na2HAsO4, 50 ml of Na3AsO4 0.2 M solutions and 100 ml of 0.1 M HCL are mixed. Ph ...
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22 views

Eutectic Phase diagram [closed]

Two metals A and B form a eutectic at 1000K. There is no solid-state solubility of A and B in each other.Eutectic composition is 40%A and 60%B. Melting points of A and B are 1200 and 1500K ...
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1answer
35 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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34 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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24 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
36 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
54 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
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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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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
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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
19 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
17 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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0answers
31 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
32 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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0answers
21 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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1answer
66 views

Why the bond strength of HCl is more than HBr?

Most people say that it is because the 3p orbital of chlorine when overlapping with the s orbital of hydrogen covers more area than when 4p orbital of bromine overlaps with the s orbital of hydrogen ...
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17 views

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
45 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
18 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
41 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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1answer
22 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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24 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
52 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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44 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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30 views

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
25 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
44 views

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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0answers
10 views

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
24 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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5answers
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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
2k views

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
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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?