18.1-1. diffusion of methane through helium. a gas of ch4 and he is contained in a tube at 101.32 kpa pressure and 298 k. at one point, the partial pressure of methane is pa1 = 60.79 kpa, and at a point 0.02 m distance away, pa2 = 20.26 kpa. if the total pressure is constant throughout the tube, calculate the flux of ch4 (methane) at steady state for equimolar counterdiffusion.

5.521 × 10⁻² mol/m².s

Explanation:

Given:

Pressure of the Methane and Helium gas = 101.32 kPa

Temperature of the Methane and Helium gas = 298 K

Partial pressure of Methane,  pA₁ = 60.79 kPa

Partial pressure of Methane at point 0.02 m away,  pA₂  = 20.26 kPa

Now,

Molar flux is given as:

Here,

= 0.675 × 10⁻⁴ m²/s (for He-CH4 at 101.32 kPa and 298 K)

Z₂ - Z₁ = 0.02 m

R is the ideal gas constant = 8.314 J/mol.K

T is the temperature =  298 K

On substituting the respective values, we get

or

= 5.521 × 10⁻² mol/m².s

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

explanation: