A solid slab of 5.15 wt% agar gel at 278 K is 6.00 mm thick and contains a uniform concentration of urea of 0.2 kmol/m3. Diffusion is only in the direction through two parallel flat surfaces 6.00 mm apart. The slab is suddenly immersed in pure turbulent water so that the surface resistance can be assumed to be negligible; i.e, the convective coefficient hm is very large. The diffusivity of urea in the agar is 4.72e-10 m2/s. a) Calculate the concentration at the midpoint of the slab and (b) 1.50 mm from the surface after 19 h. c) if the thickness of the slab is halved, what would be the midpoint concentration in 19 h.
A solid slab of 5.15 wt% agar gel at 278 K is 6.00 mm thick and contains a uniform concentration of urea of 0.2 kmol/m3. Diffusion is only in the direction through two parallel flat surfaces 6.00 mm apart.
The slab is suddenly immersed in pure turbulent water so that the surface resistance can be assumed to be negligible; i.e, the convective coefficient hm is very large. The diffusivity of urea in the agar is 4.72e-10
m2/s. a) Calculate the concentration at the midpoint of the slab and (b) 1.50 mm from the surface after 19 h. c) if the thickness of the slab is
halved, what would be the midpoint concentration in 19 h.
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