At 473K, equilibrium constant, `K_(c)` for decomposition of phosphorus pentachloride, `PCl_(5)` is `8.3xx10^(-3)`. If decomposition is depicted as :
`PCl_(5(g))hArrPCl_(3(g))+Cl_(2(g)),Delta_(r)H^(@)=124.0" kJ mol"^(-1)`
what would be the effect on reaction if the temperature is increased ?

Options

A. Reaction will shift in the backward direction.
B. Reaction will shift in the forward direction.
C. Reaction is in equilibrium.
D. Reaction first moves forward and then remains at equilibrium.

Explanation

To determine the effect of increasing temperature on the decomposition of phosphorus pentachloride (PCl₅) at equilibrium, we can follow these steps:

### Step 1: Identify the Reaction and Its Characteristics
The decomposition of phosphorus pentachloride is represented by the following equilibrium reaction:
\[ PCl_{5(g)} \rightleftharpoons PCl_{3(g)} + Cl_{2(g)} \]
Given that the enthalpy change (\(\Delta_rH^\circ\)) for this reaction is \(124.0 \, \text{kJ mol}^{-1}\), we can conclude that the reaction is endothermic because the enthalpy change is positive.

**Hint:** Identify whether the reaction is endothermic or exothermic based on the sign of \(\Delta_rH^\circ\).

### Step 2: Apply Le Chatelier's Principle
According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in temperature, the equilibrium will shift in the direction that counteracts the change. For endothermic reactions, increasing the temperature provides additional energy, which favors the formation of products.

**Hint:** Recall that for endothermic reactions, increasing temperature shifts the equilibrium towards the products.

### Step 3: Predict the Effect of Temperature Increase
Since the reaction is endothermic, increasing the temperature will shift the equilibrium to the right, towards the products \(PCl_{3(g)}\) and \(Cl_{2(g)}\). This means that more products will be formed as a result of the temperature increase.

**Hint:** Consider what happens to the equilibrium position when heat is added to an endothermic reaction.

### Step 4: Conclusion
Therefore, if the temperature is increased, the equilibrium will shift in the forward direction, resulting in the formation of more \(PCl_{3(g)}\) and \(Cl_{2(g)}\).

**Final Answer:** The reaction will shift in the forward direction, favoring the formation of products.