Question

Nitrogen and hydrogen react in the Haber process to form ammonia. All substances are in the gas phase. If 0.404 atm of nitrogen and 0.752 atm of hydrogen react, what is the partial pressure of ammonia (in mmHg) when this reaction goes 56.5 complete. The volume and temperature are constant.

Answer 1

The chemical equation involved would be :

N2 + 3H2 ====> 2NH3

DETERMINE THE LIMITING REAGENT :

N2 = 0.404 / 1 = 0.404 mol

H2 = 0.752 / 3 = 0.250 mol

So, H2 gives less number of moles, so it would be the limiting reagent.

Now, using ICE table, we have :

N

N2............+ ............. 3H2 <------>..... 2 NH3

0.404.......................0.752...... ............0............... (INITIAL)

-0.25...... ................-0.752........0.404 - 0.25 = 0.154....(CHANGE)

0.154.. .... ...................0........................0.154.......( EQUILIBRIUM)

So, partial pressure of NH3 = 0.154 atm

Now, the reaction is 56.5 Complete

So, 0.154 atm x 0.565 = 0.087 atm

Now, 1 atm = 760 mmHg

So, 0.087 atm = 760 x 0.087 mmHg

= 66.12 mmHg