Question

Question 6.13 Given

N2(g) + 3H2(g) ---> 2NH3(g) ; ΔrHθ = –92.4 kJ mol–1

What is the standard enthalpy of formation of NH3 gas?

Class XI Thermodynamics Page 183

Answer 1

N2(g) + 3H2(g) ------> 2NH3(g) ; ∆rH° = -92.4 KJ/mol

enthalpy of formation of NH3 means heat released in the formation of 1 mole of NH3 .

so, divide both sides by 2 in above reaction
1/2N2(g) + 3/2H2(g) ---> NH3(g) ;
Therefore , ∆fH° = ∆rH°/2 = -92.4/2 = 46.2 KJ/mol

Answer 2

Answer:

-46.2 KJ/mol

here's the answer and hope it helps you.