Chemistry Stack Exchange
Chemistry Stack Exchange

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.

Physical chemistry is among and one of the three "classic" branches of chemistry. It is closely related to physics, as it is the study of chemical systems and processes applying laws and concepts of physics.

Among its branches, there are:

See also:

4808 questions
23
votes
4 answers

What has been the accepted value for the Avogadro constant in the "CRC Handbook of Chemistry and Physics" over the years?

Some questions about the constant made me curious as to exactly how much the accepted value has changed over the years. I am pretty sure that I learned a rounded value of $6.023\times10^{23}$ about 1970 which would have been around the 50th edition.…
MaxW
  • 22,242
  • 2
  • 36
  • 80
21
votes
2 answers

Is there a least reactive chemical species?

As a total chemistry layman I enjoyed reading "Why doesn't $\ce{H2O}$ burn?", but it prompted another question in my mind. One of the answers there was that $\ce{H2O}$ can burn in the presence of a stronger oxidizer like fluorine, so burning stable…
David
  • 329
  • 2
  • 5
13
votes
3 answers

What are the key differences between Raoult’s Law and Henry’s Law

Raoult’s Law ($p_A = \chi_A \cdot p_A^\circ$) becomes a special case of Henry’s Law ($p_A = K_H^{px} \cdot \chi_A $) when $K_H^{px} = p^\circ_A$, but where do these laws differ from each other? There’s a statement in my text book which I’m having…
Ritwik Das
  • 2,189
  • 10
  • 28
  • 43
13
votes
1 answer

Differences between chemical physics and physical chemistry?

What makes these two seemingly identical topics separate? What does each field more focus on, like do chemical physics researchers study more the atomic/molecular interactions while the physical chememists study more macroscopic properties? I assume…
Shinaolord
  • 253
  • 1
  • 2
  • 8
10
votes
2 answers

Working with wave number equations, use trial-and-error?

I have a wave number question which I have partially solved: What transition in $\ce{He+}$ ion shall have the same wavenumber as the first line in Balmer series of $\ce{H}$ atom? (a) $7\to5$ (b) $5\to3$ (c) $6\to4$ (d) $4\to2$ Here's how I…
Abhishek Mhatre
  • 1,883
  • 12
  • 28
  • 44
10
votes
2 answers

How accurate are potential energy curves taught in high schools? What does a "real" curve look like?

I am in high school taking AP Chemistry and I am wondering how accurate the curriculum is from a quantum-mechanical perspective--specifically, how accurate are potential energy curves? The way chemistry is taught in high schools, we use Coulombic…
Raphael Esquivel
  • 117
  • 4
10
votes
3 answers

Is it possible to create hydrophobic water?

I recently saw "hydrophobic water" in my school science fair. I have no idea on the procedure of how to make it, so, can I make it? I did google it and read some articles (zero helpful) and see some images (which seem to match with the one I saw).…
dotmashrc
  • 373
  • 4
  • 14
9
votes
1 answer

Elements with no solid state

Helium superfluid-3 has got at around 2K a special liquid state with 0 viscosity with interesting properties. I am really interested in what would happen at 0K. With no kinetic energy in the particles of the compound, would it be solid? Do elements…
Alicia
  • 99
  • 1
  • 2
9
votes
3 answers

Gibbs Free Energy and Equlibrium Constant

I have some problems understanding the relationship between $\Delta$$G°$ and $K$. For example, in the reaction of $$\ce{N2 + H2 <=> 2NH3}$$ where $\Delta$$G°= - 33.5$ kJ/mol. $\Delta$$G°=- 33.5$ kJ/mol is obtained from the $\sum G^°_{\text{f,…
Ben
  • 91
  • 1
8
votes
1 answer

Boiling Point lower than Melting Point?

Under the Wikipedia entry for Metaldehyde is listed a Melting Point of $\pu{246^\circ C}$ and a Boiling point of $\pu{110^\circ C}$ (actually, it says it sublimes). How can a Boiling point be lower than the Melting Point? Even if $\pu{110^\circ C}$…
curious_cat
  • 1,638
  • 1
  • 14
  • 25
8
votes
1 answer

What does "parts by weight" or "parts by mass" specifically mean?

Equivalent mass may be defined as the number of parts by mass of a substance which combines with or displaces directly or indirectly 1.008 parts by mass of hydrogen or 8 parts by mass of oxygen or 35.5 parts by mass of chlorine. Why isn't it…
aman
  • 391
  • 2
  • 6
  • 15
8
votes
3 answers

What is the meaning of "equivalent weight" and its formula?

What is meant by "equivalent weight" and how does its formula E=M/V support the definition?
hooray_parsad
  • 89
  • 1
  • 1
  • 2
8
votes
1 answer

Why does hydrogen form on such a long time scale?

If we were trying to figure out the time scale for a gas-phase reaction between two hydrogen atoms in a molecular cloud (which has density $~\pu{10^4cm^-3}$), apparently the reaction would happen on a time scale proportional to the inverse of the…
Atreyu
  • 183
  • 4
8
votes
4 answers

How can we replace volume in ideal gas equation with V - nb?

We know that ideal gas equation is $PV= nRT$ where P is the pressure of the ideal gas and V is the volume of the ideal gas. Thus, we can write : $$ P_{\textrm{ideal}}V_{\textrm{ideal}} = nRT$$ Now from volume correction term of van der Waals'…
user281837
  • 557
  • 4
  • 11
8
votes
1 answer

What does this example mean? Slow cooling of 40% Sn alloy from 800°C to 600°C: L → L and γ → L, γ, and ε → L and ε

It's in a phase diagram topic. It's about $\ce{Cu}$-$\ce{Sn}$ phase diagram. And it has a question of: Write the schematic diagram describing the following scenarios and identifies the regions and the phases when Slow cooling of $13.1\%$ $\ce{Sn}$…
anne
  • 79
  • 4
1
2 3
…
20 21