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In industries titanium is hardened through diffusion of carbon. The concentration of carbon at 1mm into the surface of the titanium slab is 0.25kg/m^3 and at 3mm the concentration is 0.68kg/m^3. The rate at which the carbon is entering into its surface is 1.27*10-9kg/m^2.s. calculate the value of diffusion coefficient of carbon.

(a) 5.91*10^-12

(b) 5.91*10^-10

(c) 5.91*10^-11

(d) 5.91*10^-13

The question was asked by my school principal while I was bunking the class.

I'm obligated to ask this question of Fick’s Law-2 in chapter Modes and Diffusion of Mass Transfer

1 Answer

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by (39.8k points)
Correct option is (a) 5.91*10^-12

Explanation: J=-D(∂C/∂x)

∂C/∂x= Δc/Δx=(0.25-0.68)/(0.003-0.001)=-215kg/m^4

1.27*10^-19kg/m^2.s= -D*(-215kg/m^4)

D=5.91*10^-12m^2/s.

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