Vapour in Air Diffusion

Overview

The Vapour in Air Diffusion apparatus uses the Stefan tube method to measure the molecular diffusion coefficient of vapours (such as water, acetone, or benzene) in air. A liquid surface is maintained at a fixed level in a narrow tube while a dry air stream flows over the top. The rate of liquid level drop is measured and used to calculate the vapour diffusivity. Students apply the Stefan diffusion equation to experimental data and compare measured diffusivities with those predicted by Chapman-Enskog kinetic theory. The experiment is foundational for understanding molecular transport phenomena central to distillation, absorption, drying, and membrane separation processes.

Specifications