Question

question 19 (1 point)
use the following information to answer the next question.
ammonia is a colourless gas with a strong pungent
smell. it is manufactured by a process known as the
haber-bosh process. the following reaction takes
place:
n₂(g) + 3h₂(g) → 2nh₃(g)

in the above reaction, the initial pressure of the system will i, then it will
ii.

row | i | ii
a. | increase | become constant
b. | decrease | become constant
c. | increase | increase
d. | remain constant | increase
e. | remain constant | decrease

a
b
c
d
e

Explanation:

Step1: Analyze the reaction

The reaction is $\ce{N_{2}(g) + 3H_{2}(g) -> 2NH_{3}(g)}$. The total number of moles of reactants is $1 + 3 = 4$ moles, and the total number of moles of products is $2$ moles. So, as the reaction proceeds, the number of moles of gas decreases.

Step2: Relate moles to pressure

According to the ideal gas law ($PV = nRT$), at constant volume and temperature, pressure ($P$) is directly proportional to the number of moles ($n$) of gas. Initially, as the reaction starts, the moles of gas are decreasing, so the pressure will decrease (since $n$ is decreasing). Once the reaction reaches equilibrium, the number of moles of gas no longer changes, so the pressure will become constant.

Step3: Match with options

Looking at the options, row B has i as "decrease" and ii as "become constant", which matches our analysis.

Answer:

B. decrease, become constant