Question

Calculate the value of the diffusion coefficient D (in m2/s) at 547°C for the diffusion of some species in a metal; assume that the values of D0 and Qd are 5.6 × 10-5 m2/s and 177 kJ/mol, respectively.

Answer 1

Answer : The value of diffusion coefficient is, $2.97\times 10^{-16}m^2/s$

Explanation :

Formula used :

$D=D_o\times \exp \left(-\frac{Q_d}{RT}\right )$

where,

D = diffusion coefficient = ?

$D_o$ = $5.6\times 10^{-5}m^2/s$

$Q_d$ = $177kJ/mol$

R = gas constant = 8.314 J/mol.K

T = temperature = $547^oC=273+547=820K$

Now put all the given values in the above formula, we get:

$D=5.6\times 10^{-5}m^2/s\times \exp \left(-\frac{177kJ/mol}{(8.314J/mol.K)\times (820K)}\right )$

$D=2.97\times 10^{-16}m^2/s$

Thus, the value of diffusion coefficient is, $2.97\times 10^{-16}m^2/s$