Question

If the first inization energy for Li is 5.4 eV and the electron affinity for Cl is 3.61 eV, how much energy is released in the reaction of Li(g) + Cl(g) ---> Li+(g) + Cl-(g)?

Answer 1

Given : First ionization potential of Li = 5.4eV

            Electron affinity of Cl=3.61eV

            We have ΔH = ionization potential (I.P.) − Electron affinity (E.A.)

   ΔH = 5.4−3.61 = 1.80 eV = 1.80×1.6021×10^-22 KJ (1eV = 1.6021 x 10^-22 KJ )

ΔH = 2.88×10^-22KJ

            for 1 mol Avogadro's number = 6.022×10²³ per mole

. ΔH = 2.88×10^-22 KJ × 6.022 × 10²³ per mole =173.43 kJ/mole

Energy is released in the reaction of Li(g) + Cl(g) ---> Li⁺(g) + Cl^-(g) = 173.43 kJ/mole