In which direction is equilibrium expected to shift on increasing temperature in the following reactions ?
` 2SO_2 (g) + O_2 (g) hArr 2SO_3(g) , `
` " " Delta H =-42 ` kcal

Answer

To determine the direction in which the equilibrium will shift upon increasing the temperature for the reaction:

\[ 2SO_2 (g) + O_2 (g) \rightleftharpoons 2SO_3(g) \]

with a given enthalpy change (\(\Delta H = -42 \, \text{kcal}\)), we can follow these steps:

### Step 1: Identify the nature of the reaction
The reaction is given with a negative enthalpy change (\(\Delta H < 0\)), which indicates that it is an exothermic reaction. This means that heat is released when the reaction proceeds in the forward direction (from reactants to products).

### Step 2: Apply Le Chatelier's Principle
Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change. In this case, increasing the temperature is the change we are considering.

### Step 3: Determine the effect of temperature increase
Since the forward reaction is exothermic (releases heat), increasing the temperature will favor the endothermic direction of the reaction. The endothermic direction is the reverse reaction, which absorbs heat.

### Step 4: Conclusion
Thus, when the temperature is increased, the equilibrium will shift to the left (towards the reactants), favoring the formation of \(SO_2\) and \(O_2\) over \(SO_3\).

### Final Answer
The equilibrium is expected to shift to the left (towards the reactants) upon increasing the temperature.

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