The diffusion coefficient for some hypothetical small atom in a hypothetical FCC metal is ${3\mathrm{.}4}^{}{10}^{-4}c\frac{m^2}{s}$ at $2800C,$ and ${4\mathrm{.}6}^{}{10}^{-6}c\frac{m^2}{s}$ at $900C.$ Determine the activation energy for diffusion. Your answer should be reported in $ca\frac{l}{m}ol,$ and expressed as a whole number.