CHAPTER 5. THERMAL PROPERTIES AND IDEAL GASES 5.6
Example 8: Ideal gas equation 1
QUESTIONTwo moles of oxygen (O 2 ) gas occupy a volume of 25 dm^3 at a temperature of 40◦C. Calculate
the pressure of the gas under these conditions.SOLUTIONStep 1 : Write down all the information that you knowabout the gas.p =?
V = 25 dm^3
n = 2
T = 40◦CStep 2 : Convert the known values to SI units if necessary.V =
25
1000
= 0. 025 m^3T = 40 + 273 = 313 K
Step 3 : Choose a relevant gas law equation that will allow you to calculate theunknown
variable.pV = nRT
Therefore,p =
nRT
VStep 4 : Substitute the known values into the equation.Calculate the unknownvariable.p =
2 mol× 8. 3 J· K−^1 · mol−^1 × 313 K
0. 025 m^3
= 207 832 Pa = 207. 8 kPa