Chemistry Forum

Hi,
I need to solve the van der waals equation for n. And I feel pretty stupid that I can't solve it:
\((p+\frac{a*n^2}{V^2})*(V-nb)=nRT\)
thanks for your help

It's a cubic equation.

(p + (an^2/V^2))*(V-nb) = nRT

pV+ (a/V)*n^2 -nbp-(ab/V^2)*n^3-nRT=0

-pV- (a/V)*n^2 +nbp+(ab/V^2)*n^3+nRT=0

(ab/V^2)*n^3 -(a/V)*n^2 + (RT+bp)*n - pV =0

Also an equation like

ax^3 + bx^2 + cx + d = 0

use a solver like Wolfram Alpha.