Question

Calculate the mean free path of air molecules at a pressure of 7.00×10^−13 atm and a temperature of 303 K . (This pressure is readily attainable in the laboratory.) Model the air molecules as spheres with a radius of 2.00×10^−10 m .

Answer 1

82.8986 km

Step-by-step explanation:

Given:

Pressure = 7.00×10⁻¹³ atm

Since , 1 atm = 101325 Pa

So, Pressure = 7.00×10⁻¹³×101325 Pa = 7.09275×10⁻⁸ Pa

Radius = 2.00×10⁻¹⁰ m

Diameter = 4.00×10⁻¹⁰ m (2× Radius)

Temperature = 303 K

The expression for mean free path is:

`\lambda (Mean\ free\ path)=\frac {K (Boltzmann\ Constant)* Temperature}{\sqrt {2}* \pi* (Diameter)^2* Pressure}`

Boltzmann Constant = 1.38×10⁻²³ J/K

So,

`\lambda (Mean\ free\ path)=\frac {1.38* 10^(-23)* 303}{\sqrt {2}* \frac {22}{7}* (4.00* 10^(-10))^2* 7.09275* 10^(-8)}`

Mean free path = 82.8986×10³ m = 82.8986 km