All Problems

Phase Transformations

Problem 2.194

Find the pressure of saturated tungsten vapour at a temperature \(T=2000 \mathrm{~K}\) if a tungsten filament is known to lose a mass \(\mu=1.2 \cdot 10^{-13} \mathrm{~g} /\left(\mathrm{s} \cdot \mathrm{cm}^{2}\right)\) from a unit area per unit time when evaporating into high vacuum at this temperature.

Reveal Answer
p=μ2πRT/M=0.9nPap=\mu \sqrt{2 \pi R T / M}=0.9 \mathrm{nPa}