On the basis of electrical measurements, it is concluded that the equilibrium vacancy concentration in a given metal is two orders of magnitude higher at 807 C than at 498 C. What is the energy of vacancy formation (ΔHv in kJ/mol) for this metal?
two orders of magnitude mean 10^2 = 100
so use the following ratio in the Arrhenius Equation for Enthalphy of vacancy
ln(100) = Hv / R (1/T1 - 1/T2)
Make sure that you use R = 8.314 J/molK
T1 = lower temperature convert that to Kelvin
T2 = higher Temperature
The final answer will be in J/mol
So convert it to KJ/mol
Goodluck