Question

For a reaction \[ A(g)+\frac{1}{2}B(g)\rightleftharpoons C(g)+\text{heat} \] favorable conditions for the reaction to occur in the forward direction are

• A. Low \(T\) and Low \(P\)
• B. Low \(T\) and High \(P\)
• C. High \(T\) and Low \(P\)
• D. High \(T\) and High \(P\)

Hint:

According to Le Chatelier’s principle: \[ \text{Exothermic reaction } \rightarrow \text{ favored by low temperature} \] and Equilibrium shifts toward fewer gaseous moles at high pressure.

Answer 1

The Correct Option is B

Step 1: Identify the nature of the reaction.
The reaction is \[ A(g)+\frac{1}{2}B(g)\rightleftharpoons C(g)+\text{heat} \] Since heat is produced on the product side, the forward reaction is exothermic

Step 2: Effect of temperature using Le Chatelier’s principle.
For an exothermic reaction, heat behaves like a product.
When temperature is decreased, the equilibrium shifts in the forward direction to produce more heat.
Therefore, Low temperature favors the forward reaction.

Step 3: Effect of pressure.
Count the number of moles of gaseous reactants and products.
Reactant side: \[ 1+\frac{1}{2}=1.5 \text{ moles of gas} \] Product side: \[ 1 \text{ mole of gas} \] Since the number of gaseous moles decreases in the forward direction, increasing pressure shifts the equilibrium towards the side with fewer moles.
Therefore, High pressure favors the forward reaction.

Step 4: Final conclusion.
Hence, the favorable conditions are \[ \boxed{\text{Low }T\text{ and High }P} \]