Example 1: A gas with 1 atmospheric pressure has 5.0 liter volume at constant temperature. If the pressure of gas is increased twice, then what will be its volume?
Given:
P1 = 1 atmosphere
P2 = twice = 2 atmosphere
V1 = 5.0 lit
V2 = ?
Solution:
P1V1 = P2V2
V2 = P1V1/ P2
V2 = 5.0 / 2 = 2.5 lit
Example 2: The volume of an unknown gas sample is 500ml at 25 °C temperature. If the volume of a gas is made 300 ml then what temperature will have to be kept?
V1 = 500 ml
T1 = 25 °C = 25 + 273 = 298K
V2 = 300 ml
T2 = ?
V1/V2 = T1/T2
T2 = T1V2/ V1
T2 = 298 × 300 / 500 = 178.8 K
Example 3: Find out the number of moles of oxygen at 10 lit volume, 27 °C temperature and 750 mm pressure. (Atomic weight of oxygen is 16 gm/mole and constant R = 0.082 liter atm./Kelvin mole)
P = 750 mm = 750/760 atmp = 0.98 atmp
V = 10 lit
T = 27°C = 27 + 273 = 300 K
R = 0.082 lit-atmp/Kelvin mole
n = PV/RT
= 0.98 x 10 / 0.082 x 300
= 0.3983 mole of oxygen