Question

One mole of solid iron was vaporized in an oven at its boiling
point of 3433 K and enthalpy of vaporization of iron
is 344.3 kJ mol⁻¹. The value of entropy vaporization
(in J mol⁻¹) of iron is [Kerala PMT 2013]
(a) 100 (b) 10
(c) – 100 (d) 110

Answer 1

The entropy of vaporisation of iron is 100 J/ mol.

Option (a) is correct.

Explanation:

Entropy is the ratio of heat to the temperature.

i.e. S = ∆H_vap/T_b

= 344.3kJ/mol/K/3443

= 344.3 × 1000/3443 J/mol

= 3443 × 100/3443 J/mol

= 100 J / mol

Hence entropy of vaporisation of iron is 100 J/ mol. therefore, option (a) is correct choice.

Also learn more

Change in enthalpy for reaction  2H2O2(l) → 2H2O(l) + O2(g)

If heat of formation of H2O2(l) and H2O(l) are  – 188 & – 286 KJ/mol respectively.

(1) – 196 KJ/mol (2) + 196 KJ/mol  (3) + 948 KJ/mol (4) – 948 KJ/mo