Question

consider the reaction below
2nh₃(g) ↔ n₂(g) + 3h₂(g)
which is most likely the effect to the forward reaction if there is an increase in pressure of the system?
the reactant surface area increases
the reaction rate decreases
the reaction is not affected at all
the reaction stops completely

Explanation:

To determine the effect of increased pressure on the forward reaction \( 2NH_{3(g)}
ightleftharpoons N_{2(g)} + 3H_{2(g)} \), we use Le Chatelier's principle. The number of moles of gas on the reactant side is 2, and on the product side is \( 1 + 3 = 4 \). Increasing pressure favors the side with fewer moles of gas. So, the forward reaction (producing more moles of gas) is disfavored, meaning the reaction rate of the forward reaction decreases.

• "The reactant surface area increases" is incorrect because pressure doesn't affect surface area (surface area is related to particle size/state, not pressure in gas - phase reactions).
• "The reaction is not affected at all" is wrong as pressure affects gas - phase reactions with unequal moles of gas on either side.
• "The reaction stops completely" is incorrect; reactions at equilibrium shift, they don't stop.

Answer:

The reaction rate decreases.