NEET2005ChemistryThermodynamics (C)Actual
The absolute enthalpy of neutralisation of the reaction: : MgO _ (s) +2 HCl _ (a q) MgCl _ 2(a q) + H ₂ O _ ( will be:
Options
- A-57.33 ~kJ ~mol ⁻¹
- Bgreater than -57.33 ~kJ ~mol ⁻¹
- Cless than -57.33 ~kJ ~mol ⁻¹
- D57.33 ~kJ ~mol ⁻¹
Correct answer
C. less than -57.33 ~kJ ~mol ⁻¹
Step-by-step solution
MgO is salt of weak base. Thus, enthalpy of neutralisation for MgO will be less than -57.33 ~kJ ~mol ⁻¹ . Related Theory The enthalpy of neutralization of any strong acid with a strong base is always the same, i.e., 57.1 ~kJ . This is because the strong acids, strong bases and the salts they form, are all completely ionized in dilute aqueous solution.