Question

What is the relation between ∆H and ∆U?

• A. ∆H = ∆U - RT
• B. ∆H = ∆U + RT
• C. ∆H = ∆U + ∆nRT
• D. ∆H = ∆U

Answer 1

The correct option is C

∆H = ∆U + ∆nRT

The change in enthalpy during a process at constant pressure is given by the expression

∆H = ∆U + P∆V

Substituting the value of P∆V We get

∆H = ∆U + (∆n) RT

Here ∆n is the change in the number of moles of gaseous species.