In: Chemistry
Calculate delta H rxn (at 500K) for the formation of 1 mol of ammonia gas. (show worked out solution)
Nitrogen gas (N2) and hydrogen gas (H2) can be made to combine to form NH3, or ammonia gas.
The reaction is N2 + 3H2 2NH3
This equation says that one mole of N2 requires three moles of H2 for a complete reaction, and this would then yield two moles of NH3.
Nitrogen |
+ |
Hydrogen |
Ammonia |
||
N2 |
+ |
3H2 |
2NH3 |
||
+ |
3 H-H |
2NH3 |
|||
1 mole of N2 |
+ |
3 moles of H2 |
2 moles of ammonia |
||
28 g of N |
+ |
6 g of H |
34 g ammonia |
H= -92.4 KJ/mol
92.4kJ of energy is released for every one mole of N2
92.4kJ of energy is released for every three moles of H2
92.4kJ of energy is released for every two moles of NH3 produced.
Hence one mole of NH3 produces 92.4/2 = 46.0 kJ/mol energy
H = m*c*T
where m is mass of reactant
c is specific heat of product &
T is temperature
H = 0.02kg*6.74kJ/kgK*500
=67.4kJ/mol