Ideal Gas Equation of State

Description

Origin: HP-34C Student Engineering Applications, August 1979, p. 20

Many gases obey the ideal gas laws quite closely at reasonable temperatures and pressures. This program calcualtes any one of the four variables when data for the other three and the universal gas constant are entered.

Equation:

PV = n RT

where:

P is the absolute pressure
V is the volume
n is the number of moles present
R is the Universal Gas Constant
T is the absolute temperature

Remarks:
Example 1:

.63 moles of air are enclosed in 25,000 cm3 of space at 1.200 K. What is the pressure in bars? In atmosperes?

83.14 STO 0
25000 STO 2
.63 STO 3
1200 STO 4
GSB 1 → 2.5142 (P, bars)
82.05 STO 0
GSB 1 → 2.4812 (P, atm)

Example 2:

What is the specific volume (ft3/lb) of a gas at atmospheric pressure and a temperature of 513°R? The molecular weight is 29 lb/lb-mole.

.7302 STO 0
1 STO 1
29 1/x STO 3
513 STO 4
GSB 2 → 12.9170 (V, ft3/lb
What is the density?
1/x → 0.0774 (ρ, lb/ft3)
What is the density at 1.32 atm and 555 °R?
1.32 STO 1
555 STO 4
GSB 2 1/x → 0.0945 (ρ, lb/ft3)

Program Resources

Labels

Name Description
 1 Caculate P
 2 Caculate V
 3 Caculate n
 4 Caculate T
 8 Calculate term nRT
 9 Calculate term PV/n

Storage Registers

Name Description
 0 Universal Gas Constant in appropriate units
 1 Pressure P
 2 Volume V
 3 # of moles n
 4 absolute Temperature T

Program

Line Display Key Sequence Line Display Key Sequence
000 020 32 9 GSB 9
001 42,21, 1 f LBL 1 021 45 3 RCL 3
002 32 8 GSB 8 022 10 ÷
003 45 2 RCL 2 023 44 4 STO 4
004 10 ÷ 024 43 32 g RTN
005 44 1 STO 1 025 42,21, 8 f LBL 8
006 43 32 g RTN 026 45 3 RCL 3
007 42,21, 2 f LBL 2 027 45 0 RCL 0
008 32 8 GSB 8 028 20 ×
009 45 1 RCL 1 029 45 4 RCL 4
010 10 ÷ 030 20 ×
011 44 2 STO 2 031 43 32 g RTN
012 43 32 g RTN 032 42,21, 9 f LBL 9
013 42,21, 3 f LBL 3 033 45 1 RCL 1
014 32 9 GSB 9 034 45 2 RCL 2
015 45 4 RCL 4 035 20 ×
016 10 ÷ 036 45 0 RCL 0
017 44 3 STO 3 037 10 ÷
018 43 32 g RTN 038 43 32 g RTN
019 42,21, 4 f LBL 4