Answer:
E = 15.7 KJ/mol
Explanation:
The number of vacancies in a metal is given by
n = n₀ [tex]e^{-E/KT}[/tex]
They tell us that
n = 5 no
We replace
5 n₀ = n₀ e^{-E/KT}
-E / KT = ln 5
E = KT ln 5
E = 1,381 10⁻²³ 1170 ln 5
E = 2.6 10⁻²⁰ J
To take (J / mol) we multiply between Avogadro's number
E = 2.6 10⁻²⁰ 6.022 10²³
E = 1.57 10⁴ J / mol
E = 15.7 KJ/mol