A sample of ammonia gas NH3 is completley decomposed to nitr

A sample of ammonia gas (NH3) is completley decomposed to nitrogen gas and hyrdogen gas. If the total pressure at the end of the reaction in 866mmHg, what was the initial pressure of the ammonia? Is this reaction a redox reaction? Explain.

Solution

2NH3 ---> N2 + 3H2

Let the initial Pressure be x

hence

x - 2y ---> y and 3y

At the end of the reaction partial pressure of NH3 becomes 0

hence

x - 2y = 0

also

y + 3y = 866 mm

y = 216.5 mm of Hg

hence the initial pressure is

x = 2 * 216.5 mm of Hg

x = 433 mm of Hg