Maple Solutions to the Chemical Engineering Problem Set

0.02
0
-0.02
-0.04
-0.06
-0.08
-0.1
0.2
z
0.4
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0.8
1
This illustration clearly shows the only real root; the two complex roots are near the maximum in
the curve. Under slightly different conditions the curve will cross the z axis in three places and we
would have three real roots.
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>
Example 2 and 3
Calculate the compressibility of ammonia at a reduced pressures of 1, 2, 4, 10, and 20 at a
temperature of 450 K.
The critical properties of ammonia are
> CriticalProps[NH3]:={T[c] = 405.649994, P[c] = 11280000.0}: CriticalProps[NH3];
{ T = 405.649994 ,
P = .112800000 10 }
c
c
8
where the temperature is in kelvin and the pressure in pascals.
The reduced pressure is related to the actual pressure by
> prdef:= P[c]=P[r]/P: prdef;
P
r
P =
c P
We will use this relation in the substitution to follow
The temperature and pressure of interest (in the same units) are
> Tspec:=T=450: Tspec;
T = 450
The desired dimensionless pressures are given in a list as
> prlist := [1,2,4,10,20]: prlist;
[ 1, 2, 4, 10, 20]
We compute the compressibility at all reduced pressures in one loop
>
> for Pr in prlist do
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