# 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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### What is the hydrated diameter of a lithium ion？

When salts dissolve in water, the anions, cations, and strongly polar water molecules undergo hydration reactions, resulting in the formation of hydrated ions with a specific number of coordinated ...
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1 vote
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### Why do reduced variables for gases use their critical constants?

I understand why it's useful to have reduced variables, especially as it is the basis for the theorem of corresponding states. However, I'm having a hard time understanding why the critical constants ...
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### Bancroft's point

In the last problem (Problem 10.43) within the problem section of Chapter 10 in "Introduction to Chemical Engineering Thermodynamics" (J.M. Smith, H.C. Van Ness, M.M. Abbott, McGraw-Hill, ...
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### A first order gaseous reaction - getting the rate law

There is a specific example cited in our NCERT Class 12 textbook, to find out the rate law equation for a general gaseous reaction, $$\ce{A->B + C}$$ It describes the entire procedure as shown: ...
129 views

### Why is the ionic product of water also the equilibrium constant of dissociation of water?

This answer presents a derivation of the value of ionic product of water at $25^{\circ}\text{C}$. The relation $K_\text{eq} = \operatorname{e}^{-\frac{\Delta_\text{r}G^{\circ}}{RT}}$ is used for the ...
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### NaOH etching time and temperature for Stainless Steels (SS-304) for Surface Preparation for coating

To improve adhesion of TiO2 coatings on stainless steel sample I am treating SS-304 with 1M NaOH for functionalizing the surface with metal hydroxide groups as well as increasing roughness. What would ...
106 views

### How salt helps to melt ice even when there is no dynamic equilibrium between water and ice?

I am a high school student and I am confused about freezing point depression. We say that when in winter's it gets even colder than normal freezing point Temperature then we use solute to melt ice ...
1 vote
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### History of Azeotrope (azeotropic mixtures)

I'm currently researching the history of azeotropic mixtures for an essay, and I've come across some interesting information. The term "azeotrope" was coined in 1911 by English chemists John ...
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### Why is my Briggs-Rauscher reaction not oscillating?

I have been trying to run the Briggs-Rauscher reaction following this guide, which is pretty similar to other guides out there, yet the reaction is failing to not only oscillate, but display any color ...
208 views

### What is meant by "the position of equilibrium lies left (or right)"?

I am a high school student currently learning about equilibrium. I was told that when there are more products of a reaction formed compared to reactants when the reaction reached the equilibrium, the ...
324 views

### How can the double-layer capacitance be constant in the Helmholtz model?

The differential capacitance of ideal electrochemical double layers is constant, as the surface charge $\sigma$ linearily increases with the applied surface potential $\Psi$ relative to the point of ...
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### The existence of a principal quantum level or energy shell after the loss of an electron from the outer shell of an atom

With the loss of an electron from $\ce{Li}$ ($\mathrm{1s^2\ 2s^1}$), we get $\ce{Li+}$ ($\mathrm{1s^2}$), then the 2nd shell where the electron had been revolving in $\ce{Li}$ will get disappeared or ...
1 vote
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### Gibbs phase rule for azeotrope and Solid-Liquid phase diagram

Azeotrope An azeotrope is a mixture of two or more components in fluidic states whose proportions cannot be altered or changed by simple distillation Applying the phase rule to azeotrope. There are 2 ...
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### Surface treatment and current density: electrodeposition of Cd and Ag

I'm currently working on a cadmium and silver electrodeposition project. Let me explain: I'm doing electrolytic surface treatment on low-alloy steels as well as stainless steels. At present, we have ...
1 vote
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### How to indicate that a substance is in a standard state?

An superscript circle or Plimsoll is typically used to indicate that a thermodynamic property is that of a substance in its standard state. On the other hand, when writing a chemical equation we ...
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1 vote
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### Dependence of Butler-Volmer equation on n for multiple transferred electrons

I was working on an exercise sheet regarding the RDE results of an irreversible electrochemical reduction, with n transferred electrons. In it, we had to plot the Koutecky-Levich plot at different ...
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### How do pencil erasers erase on a fundamental level? [duplicate]

One could say we're taking advantage of friction, but I want to dig deeper down to molecular/atomic level: what's the process or chain that happens when one erases from a macroscopic to a more ...
92 views

### Quantum Mechanics expectation value help

I am working on the following question: I've so far done the first part of a, finding $H_{so}$ in terms of J L and S. I'm struggling to see how to relate that to $E_{LSJ}$ as it involves the ...
143 views

### Boiling point, pressure, and Gibbs free energy

The water boiling process can be represented by the equation: $$\ce{H2O(l) → H2O(g)} \tag{1}$$ Since free energy depends on pressure $$\left(\frac{\partial G}{\partial P}\right)_T = V \tag{2}$$ ...
148 views

### Mechanism of adhesion of particles on solid surfaces [closed]

What is the mechanism of adhesion of particles on solid surfaces? How does anything stick to anything, for that matter? Why does cigarette smoke stay so stubbornly on our bodies? Why does perfume also ...
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1 vote
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### Does Hess' law in standard conditions involve consuming all reactants?

The standard free energy change for equilibrium problems is relative to both reactants AND products starting at 1 molar. Hess’s law takes the sum of the values for products minus the sum of the values ...
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