Question

The Enthalpy change does not depend on the:

• A. Physical state of reactants & products
• B. Use of different reactants for same products
• C. Nature of intermediate reaction steps
• D. Difference in initial or final temperatures of involved substances.

Answer 1

The correct option is C

Nature of intermediate reaction steps

(a) $\Delta$ ng = number of moles of gaseous products - number of moles of gaseous reactants Thus ∆ng depends on the physical state of reactants & products $\Delta H=\Delta U+\Delta ngRT$ at constant pressure.

(b) By using different reactants for same products the $\Delta U$ will change. Thus use of different reactants for same products will change enthalpy

(c) Difference in initial or final temperatures of involved substances changes the value of $\Delta U$

But,

(d) The nature of intermediate reaction steps do not affect the enthalpy change.