I have a MATLAB assignment$--$have to write a script to find final pressure using the ideal gas law and the van der waals equation of state. I have converted the volume from $1$ liter to $\mathrm{.}001$ m$^3$ and converted $5\mathrm{.}536$ from bar to $0\mathrm{.}5536$ kPa. I$\text{'}$m getting a correct result for the ideal gas law but not for van der waals. Correct pressures are $9528\mathrm{.}37$ kPa for IGL and $7932\mathrm{.}743$ kPa for van der Waals. Percent difference should be $20\mathrm{.}11\%.$ I have cut and pasted my script here.

T$=573$; $\%$ Temperature, T $[$K$]$

V$=\mathrm{.}001$; $\%$ Volume, V $[$m$^3]$

n$=2$; $\%$ moles, n $[$mol$]$

a$=0\mathrm{.}5536$; $\%$ intermolecular force, a $[$m$^6$ Pa mol$^-2]$

b$=3\mathrm{.}049$e$-5$; $\%$ volume of molecules, b $[$m$^3$ mol$^-1]$

R$=8\mathrm{.}314$; $\%$ gas constant, R $[$kPa m$^3$ kmol$^-1$ K$^-1]$

R$=0\mathrm{.}08314$; $\%$ gas constant $[$L bar mol$^-1$ k$^-1$

P$\_$IGL$=(($n$*$R$*$T$)/$V$)$; $\%$ IGL ideal gas law, calculation for pressure, $[$kPa$]$

P$\_$vdW$=(($n$*$R$*$T$)/($V$-($n$*$b$)))-(($a$*$n$^2)/$V$^2)$; $\%$ van der Waals, calculation for pressure, $[$kPa$]$

Pdiff$=$abs$(($P$\_$vdW$-$P$\_$IGL$)/$P$\_$vdW$)*100$; $\%$ percent difference

$\%$ Display the results

disp$([\text{'}$Pressure from Ideal Gas Law $($IGL$)$: $\text{'},$num$2$str$($P$\_$IGL$),$ 'kPa'$])$;

disp$([\text{'}$Pressure from van der Waals $($vdW$)$: $\text{'},$num$2$str$($P$\_$vdW$),$ 'kPa'$])$;

disp$([\text{'}$Percent Difference',num$2$str$($Pdiff$*100),\text{'}\%\text{'}])$;