Represent the potential energy/enthalpy change in the following processes graphically. (a) Throwing a stone from the ground to roof. (b) 1/2 H 2 (g) + 1/2 Cl 2 (g) ⇋ HCl(g) Δ r H Θ = –92.32 kJ mol –1 In which of the processes potential energy/enthalpy change is contributing factor to the spontaneity?

Question

Philoid · Accepted Answer

o For the process involved in (a) Throwing a stone from the ground to roof, as the potential energy will be increasing as the stone would cover greater distance from the ground, graphically it can be represented as:

o For the reaction : (b) 1/2 H₂(g) + 1/2 Cl₂(g) ⇋ HCl(g) whose Δ_rH^Θ = –92.32 kJ mol ^–1, as it is an exothermic reaction, heat is evolved and the ∆H value (enthalpy of reaction) decreases (eventually its is negative) throughout the process. The graphical representation will be :

o Amongst these two processes, in the process or reaction (b) the potential energy/enthalpy change is contributing factor to the spontaneity. As the spontaneous reactions are the one which occurs on their own, no external work is required. And the enthalpy is decreasing through the process going from reactant tom products is a sign of spontaneity as the driving force for a chemical reaction is within itself and it is the lowering of energy which is happening in (b) and not in (a) as there is some extra work required to start the process.

Represent the potential energy/enthalpy change inthe following processes graphically.(a) Throwing a stone from the ground to roof.(b) 1/2 H2(g) + 1/2 Cl2(g) ⇋ HCl(g) ΔrHΘ = –92.32 kJ mol–1In which of the processes potential energy/enthalpy change is contributing factor to the spontaneity?