Question
Chemistry Question on Enthalpy change
Consider the following changes M(s)⟶M(g) M(g)⟶M2+(g)+2e−…(1) M(g)⟶M+(g)+e−…(2) M+(g)⟶M2+(g)+e−… (3) M(g)⟶M2+(g)+2e−…(4) The second ionisation energy of M could be determined from the energy values associated with
1 + 2 + 4
1 + 5 - 3
2 + 3 - 4
44684
44684
Solution
The second ionisation energy is the energy that is required to remove the second electron from a positive charge ion. The second ionization energy is greater than the first ionization energy. For example: Li → Li+ + e- and second ionization energy is Li+ → Li2+ + e-
According to the question 5-1 should be done to get the second ionisation energy.
M (g) → M2+ +2e- - M (g) → M+ +e-
Second ionisation energy is the amount of energy required to take out an electron from the monopositive cation.
M(g)−>M2+(g)+2e− .......(5)
M(g)−>M+(g)+e− ....(3)
On subtracting eq(iii) form e (v) we get,
M+(g)−>M2+(g)+e−