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:
- At low temperatures or high pressures the ideal gas law does not represent the behaviour of real gases
- The value of R used must be compatible with the units of P, V, T
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 |
|
|
|
|
|