Question

Ammonia gas at 76 cm Hg pressure was connected to a manometer. After sparking in the flask, ammonia is partially dissociated as follows :
`2NH_(3) (g) hArr N_(2) (g) + 3H_(2) (g)`
the level in the mercury column of the manometer was found to show the difference of 18 cm. What is the partial pressure of `H_(2) (g)` at equilibrium ?
A. 18 cm Hg
B. 9 cm Hg
C. 27 cm Hg
D. 24 cm Hg

Answer 1

Correct Answer - C
`{:(,2NH_(3) (g),hArr,N_(2) (g) ,+ 3H_(2) (g)),(t_(0),76,,0," "0),(t_(eq),76 - 2x,,x," "3x):}`
Total pressure after dissociation `= 76 - 2x + x + 3 x = 76 + 2x`
`:.` Increase in pressure `= 2x = 18`
`x = 9 cm`
Partial pressure of `H_(2) = 3 x = 27 cm`