Question

How is the reaction equilibrium of the following reaction affected by the change in temperature? Explain. A + 2B C+D AH = -250 KJ. mol-'

Answer 1

The given chemical reaction is A + 2B ---------> C + D   ΔH = -250 kJ/mole

Here the negative value of Enthalpy of reaction (ΔH) indicates that the reaction is an Exothermic reaction. i.e heat is releases in this reaction on product side. So the effect of change in tempereature here on the direction of reaction is determined as per Li-chatelier's principle.

We can wite this reaction as-   A + 2B ---------> C + D + Heat

Now according to Li-chatelier's principle-

i) If we increase the concentration of one of the products ----> then the reaction shifts to left to form more reactants.

So here if we increase the temperature, that means we are increasing the amount of one of thee products. As a result, the reaction shifts to left and more reactanstts (i.e A and B) are formed

ii) If we decrease the concentration of one of the products ----> then the reaction shifts to Right to form more Products.

So here if we decrease the temperature, that means we are decreasing the amount of one of thee products. As a result, the reaction shifts to Right and more products (i.e C and D) are formed