emblem
Van der Waals vs. ideal
Finds one of P, V, and T, given the other two values.
2025.Feb.22 20:46:39
Solve for P, V or T ? Dependent variable (to solve for). •
Two remaining   (order: P V T) Independent variables (e.g., P T if V is sought). •
Extremes, respectively   Extremes for graph. •
a, b L² atm/mol², L/mol Van der Waals parameters. •
n Number of moles. •
Show values ? Shows the graph coordinates.

Solves the van der Waals equation, (P + a n² ⁄ V²) (V − n b) = n R T, relating pressure, volume, temperature, and number of moles, P (atm), V (L), T (K), and n.

The computation assumes that two of the three variables are given, and solves for the other. (Notice that, in the case of finding V from P and T, a cubic has to be solved.) The basis data are for chlorine (Cl2).

A 3-D graph is shown of the selected dependent variable as a function of the other two, these varying between the extremes given.

Other suggested data: P; 4 298; 3, 5, 290, 310; (...). Result, vdW 28.2, ideal 43.1 atm.

References: Plate: vanderWaals

• Van der Waals equation of state (HyperPhysics, Georgia State Univ.).

• 10.9: Real gases: deviations from ideal behavior, with (search) 'constants for some common gases' (Chemistry LibreTexts).

• V. d. Waals constants for real gases (Tom Stretton).

• Van der Waals law calculator (WebQC.org).

• Berberan-Santos, Mário, The van der Waals equation: analytical and approximate solutions.pdf (DEQ, IST, Univ. of Lisbon).

• Wikipedia: Cubic equation (old page)

• 1775-01-20: Ampère, André-Marie (1836-06-10)

 
 
Valid HTML 4.01! IST http://web.ist.utl.pt/~ist11038/compute/com/Fx-VanDerWaals.php
Created: 2016-04-30 — Last modified: 2017-01-21