Repeat problem 3.40 for each gas having a temperature of (a) 200 K, and (b) 500 K.

Question

(a)
Given: T = 200 K, 0.9 ? Z ? 1.10

(b) T = 500 K

What will be an ideal response?

Answer 1

The compressibility chart will be used to find the values of PR at the acceptable limits of
the compressibility chart for each gas.
(a) H2: Tc = 33.3 K, Pc = 1,300 kPa
TR = T/Tc = 6.0

So, for Z = 0.90: Never achieved: take P = 0
For Z = 1.10: PR = 7, so P = PcPR = 9,100 kPa
Acceptable Pressure range: 0 ? P ? 9,100 kPa

(b) O2: Tc = 154.8 K, Pc = 5,080 kPa
TR = T/Tc = 1.29
So, for Z = 0.90: PR = 0.68, so P = PcPR = 3,450 kPa, and also at PR = 7, so P = 35,600
kPa
For Z = 1.10: PR = 8.6, so P = PcPR = 43,700 kPa
Acceptable Pressure range: P ? 3,450 kPa and 35,600 kPa ? P ? 43,700 kPa

(c) CO2: Tc = 304.2 K, Pc = 7,390 kPa
TR = T/Tc = 0.657
So, for Z = 0.90: PR = 0.05, so PcPR = 370 kPa
For Z = 1.10: PR = unknown,
Acceptable Pressure range: P ? 370 kPa

(b) T = 500 K

(a) H2: Tc = 33.3 K, Pc = 1,300 kPa
TR = T/Tc = 15
So, for Z = 0.90: Never achieved: take P = 0
For Z = 1.10: PR = 15, so P = PcPR = 19,500 kPa
Acceptable Pressure range: 0 ? P ? 19,500 kPa

(b) O2: Tc = 154.8 K, Pc = 5,080 kPa
TR = T/Tc = 3.22
So, for Z = 0.90: Never achieved: take P = 0
For Z = 1.10: PR = 6.4, so P = PcPR = 32,500 kPa
Acceptable Pressure range: 0 kPa ? P ? 32,500 kPa

(c) CO2: Tc = 304.2 K, Pc = 7,390 kPa
TR = T/Tc = 1.64
So, for Z = 0.90: PR = 2, so P = PcPR = 14,800 kPa and PR = 5.2, so P = 38,400 kPa
For Z = 1.10: PR = 9, so P = 66,500 kPa
Acceptable Pressure range: P ? 14,800 kPa and 38,400 kPa ? P ? 66,500 kPa