I'm currently having trouble solving for n in the VdW gas equation for a calculator in excel for a variation of gases. I know there is a calculator on the site and I've tried my hand at doing the algebra, but I keep seeming to be just a touch off.
Is there anyone out there that has solved for n in this equation? If so, what is it???
Thanks!
Van der Waals Equation  solve for n
Moderators: expert, ChenBeier, Xen

 Newbie
 Posts: 1
 Joined: Wed Feb 26, 2020 11:25 am
 ChenBeier
 Distinguished Member
 Posts: 493
 Joined: Wed Sep 27, 2017 7:25 am
 Location: Berlin, Germany
p = nRT/(V  nb) n^2 *a/V^2
p ( V  nb) = nRT  n^2*a*(Vnb)/V^2
pV^3 pnbV^2 = nRTV^2 n^2aV  n^3ab
n^3ab + n^2aV  nRTV^2 pnbV^2 + pV^3 = 0
n^3ab + n^2aV  n( RTV^2+pbV^2) + pV^3 = 0
n^3 + n^2*V/b  n( RTV^2+pV^2)/ab +pV^3/ab =0
This cubic equation is a type of
ax^3 + bx^2 + cx+ d = 0
This kind of questions have to be solved with tools of mathematics like curve discussion and differential equation, etc.
p ( V  nb) = nRT  n^2*a*(Vnb)/V^2
pV^3 pnbV^2 = nRTV^2 n^2aV  n^3ab
n^3ab + n^2aV  nRTV^2 pnbV^2 + pV^3 = 0
n^3ab + n^2aV  n( RTV^2+pbV^2) + pV^3 = 0
n^3 + n^2*V/b  n( RTV^2+pV^2)/ab +pV^3/ab =0
This cubic equation is a type of
ax^3 + bx^2 + cx+ d = 0
This kind of questions have to be solved with tools of mathematics like curve discussion and differential equation, etc.