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Question
Solve the following.
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.
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Solution
Given:
V = 0.5 m3,
P = 2.0 × 102 kPa = 2.0 × 105 Pa
T = 300 K,
R = 8.314 J K−1 m−1
To find: Number of molecules of methane gas
Formula: PV = nRT
Calculation: According to ideal gas equation,
n = `"PV"/"RT"`
`n =(2.0xx10^5xx0.5)/(8.314xx300)`
n = 40 mol
Number of molecules = n × NA = 40 × 6.022 × 1023 = 2.4088 × 1025 ≈ 2.409 × 1025
The number of molecules of methane gas present is 2.409 × 1025 molecules.
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