Ammonia gas is diffusing at a constant rate through a layer of stagnant air 1 mm

Question

Ammonia gas is diffusing at a constant rate through a layer of stagnant air 1 mm thick. Conditions are such that the gas contains 50 per cent by volume ammonia at one boundary of the stagnant layer. The ammonia diffusing to the other boundary is quickly absorbed and the concentration is negligible at that plane. The temperature is 295 K and the pressure atmospheric, and under these conditions the diffusivity of ammonia in air is 1.8 Times 10-5 m2/s. Estimate the rate of diffusion of ammonia through the layer.

Explanation / Answer

P = CRT
=> C = P/RT = 1/(0.0821*295) = 0.0413 mol/L;
thickness, x= 1mm = 10-3 m

concentration of ammonia in bulk, Cb = 0
concentration of ammonia at surface, Cs = 0.0413 M = 4.13 * 10-2 M;
Cs-Cb = 4.13 * 10-2 M;

rate of diffusion of ammonia = D*(Cs-Cb)/x = (1.8 * 10-5 m2/s)*(4.13 * 10-2 mol/10-3m3) /(10-3m) = 0.74 mol/m2-s

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.