Calculate the number of molecules of methane in 0.50 m3 of the gas at a pressure of 2.0 × 102 kPa and a temperature of exactly 300 K.
Given :
V = 0.5 m3,
P = 2.0 × 10 kPa = 2.0 × 105 Pa
T = 300 K,
R = 8.314 J K-1 mol-1
To find :
Number of molecules of methane gas
Formula :
PV = nRT
Calculation :
According to ideal gas equation,
n = \(\frac{PV}{RT}\)
= \(\frac{2.0\times 10^5 \times 0.5}{8.314 \times 300}\)
= 40 mol
Number of molecules = n × NA
= 40 × 6.022 × 1023
= 2.4088 × 1023 ≈ 2.409 × 1025
∴ The number of molecules of methane gas present is 2.409 × 1025 molecules.