Question

A flask is filled with 6.0 atm of N2 and 6.0 atm of H2. The gases react and NH3 is formed. What is the pressure in the flask after the reaction occurs as completely as possible

Answer 1

Answer: The total pressure in the flask is 8.0 atm

Explanation:

We are given:

Initial partial pressure of nitrogen gas = 6.0 atm

Initial partial pressure of hydrogen gas = 6.0 atm

The chemical equation for the reaction of nitrogen and hydrogen gas follows:

$N_2+3H_2\rightarrow 2NH_3$

By Stoichiometry of the reaction:

3 atm of hydrogen gas reacts with 1 atm of nitrogen gas

So, 6.0 atm of hydrogen gas will react with = $\frac{1}[3}\times 6=2atm$ of nitrogen gas

As, given amount of nitrogen gas is more than the required amount. So, it is considered as an excess reagent.

Thus, hydrogen gas is considered as a limiting reagent because it limits the formation of product.

Pressure of nitrogen gas left = [6 - 2] = 4.0 atm

By Stoichiometry of the reaction:

3 atm of hydrogen gas produces 2 atm of ammonia gas

So, 6.0 atm of hydrogen gas will produce = $\frac{2}{3}\times 6=4atm$ of ammonia

Total pressure in the flask = [4 + 4] = 8.0 atm

Hence, the total pressure in the flask is 8.0 atm