# Questions tagged [van-der-waals-behavior]

Questions with substantial discussion on the behavior of real gases using the van der Waals model (as opposed to just calculations with the van der Waals equation, or a casual reference to the van der Waals model).

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### van der Waals equation for real gases [closed]

At what kind of temperatures, pressures, and volumes must I ignore the van der Waals constants $a$ and $b$? Please explain in detail as I really find these stuff hard while I solve questions at JEE ...
33 views

### Does scotch tape only use van der Waals forces? [closed]

Does it also make use of covalent bonds to stick to surfaces?
41 views

### What is the value of isothermal compressibility of a van der Waals gas at critical point?

For a van der Waals gas, isothermal compressibility is $$\kappa=\frac{V^2(V-nb)^2}{nRTV^3-2an^2(V-nb)^2}$$ If one substitutes the values of critical temperature and volume in this formula, isothermal ...
37 views

### Chemicals to increase surface tension of water

I want to increase the surface tension of water by 1.2 - 2 times. How about adding one or more chemical substances to the water that can possibily increase its surface tension by the desired amount? ...
53 views

### Deviation from ideal gas law curves

So I was reading through my textbook on deviations from an ideal gas, and they had plotted a curve of experimental PV/nRT against the pressure. They talk a lot about why the volume is really smaller ...
231 views

### Compressibility factor (Z) of a real gas [closed]

I was wondering whether the compressibility factor of a real gas (given by $Z = V_{\mathrm{real}}/V_{\mathrm{ideal}}$) is supposed to be measured while keeping pressure constant? I was attempting to ...
43 views

### Why is it experimentally difficult to accurately find the critical volume of a real gas?

I was reading up on the derivation of the values of various critical state functions( $\ce{Vc}$, $\ce{pc}$ and $\ce{Tc}$) from the Van der Waals equation (Physical Chemistry by G.W. Castellan). There, ...
125 views

### Finding (∂U/∂V )T = n^2a/V^2 for a van der Waals gas [closed]

$\displaystyle dU = \left(\frac{\partial U}{\partial T}\right)_V dT + \left(\frac{\partial U}{\partial V}\right)_T dV \to dU = C_v dT - C_v\left(\frac{\partial T}{\partial V}\right)_U dV$ Not sure ...
693 views

### How are the Van der Waals constants a and b related to each other?

I know that the constant a represents the attractive forces between the molecules while the constant b represents the size/repulsion between them. Does that mean that a and b are "inversely ...
25k views

### Calculating Compressibility factor from the Van der Waals' Gas equation

So this problem has been bugging me for a long time. According to Wikipedia the compressibility factor $Z$ is defined as the ratio of the volume occupied by a real gas divided by the volume occupied ...
1k views

### Validity of van der Waals equation [duplicate]

Van der Waals had stated that at high pressure, pressure exerted by ideal gas on the walls of container is more than real gas. However in this graph, one can clearly see that, the at high pressure ...
2k views

### Are van der Waals coefficients independent of temperature?

In the van der Waals equation for real gases, the coefficients $a$ and $b$ are used as respective correction terms for pressure and volume in the ideal gas equation. I want to know whether the van ...
4k views

### Van der Waals real gas equation

Van der Waals corrected the ideal gas equation for real gases and gave the following equation: $$\left(p+\frac{an²}{V^2}\right)\left(V-nb\right)=nRT$$ I’m very confused about one aspect of this ...
4k views

### How are van der Waals parameters determined experimentally?

If the ideal gas law $PV=nRT$ is not enough, as a second approximation the van der Waals equation $$\left(P+a\frac{n^2}{V}\right)\left(V-nb\right)=nRT$$ is applied. The constants $a$ and $b$ are van ...
The van der Waals equation for a real gas is: $$RT =\left(p+\frac{a}{V_\mathrm{m}^2}\right)(V_\mathrm{m}-b)$$ We have understood this formula by saying that $a$ is the term which is for force of ...