Question

Calculate the change in internal energy at 298 K for the formation of one mole of ammonia, if
the enthalpy change at constant pressure is - 42.0 kJ mol".
(Given : R = 8.314 J K mol-')

Answer 1

Explanation:

N  

2

​  

+3H  

2

​  

→2NH  

3

​  

 

Δn=2−(1+3)=−2

ΔH=ΔU+ΔnRT

ΔU=ΔH−ΔnRT

ΔU=−42.0 kJ/mol−[(−2)×8.314×10  

−3

 kJ/mol/K×298 K]

ΔU=−37.0 kJ/mol