$$ \begin{aligned} &\text { Calculate the value of } \Delta G \text { at } 700 \mathrm{~K} \text { for the reaction } n X \longrightarrow m B .^{-1}\\\ &\text { Given that value of } \Delta H=-113 \mathrm{~kJ} \mathrm{~mol}^{-1} \text { and } \Delta S=-145 \mathrm{JK} \mathrm{mol}^{-1} \text { . } \end{aligned} $$

Enthalpy change, denoted as abla H , refers to the heat content change during a chemical reaction at constant pressure. It is a measure of the total energy of a thermodynamic system, including both internal energy and the product of pressure and volume. This value can be either positive or negative, indicating whether the reaction is endothermic (absorbing heat) or exothermic (releasing heat), respectively.

For example, if a reaction releases heat to the surroundings, abla H is negative, as is the case in our exercise with a value of -113 kJ/mol. This indicates an exothermic reaction where energy is expelled into the environment. In practical terms, ensuring that abla H is consistently measured in Joules (J) or kilojoules (kJ) is crucial, as miscalculations can occur if unit conversions are not handled properly. Thus, converting the given enthalpy change from kJ to J is a necessary step to align with the standard SI unit of Joules for subsequent calculations.abla H and will significantly impact abla G, Gibbs Free Energy's computation, as seen later.

Entropy change, denoted as abla S, is a key concept in thermodynamics that quantifies the disorder or randomness in a system. During a chemical reaction, the entropy of a system can increase or decrease, and this change is crucial for determining the spontaneity of the reaction. An increase in entropy (abla S > 0) suggests a transition to more disorder, while a decrease (abla S < 0) suggests a system becoming more ordered.

It is essential to keep entropy in units of J/(mol·K) when performing calculations involving temperature. As we see in the provided exercise, the entropy change is -145 J/K·mol, indicative of a decrease in system disorder during the reaction. This negative value plays a role in calculating Gibbs Free Energy and helps in understanding the feasibility of the chemical process from a thermodynamic standpoint.

Temperature is a fundamental concept in thermodynamics that measures the average kinetic energy of the particles in a substance. It is always measured on an absolute scale, such as Kelvin (K), to avoid negative temperatures, which have no physical meaning in this context. A higher temperature usually equates to greater particle movement and higher entropy, influencing a reaction's direction and extent.

In calculations involving Gibbs Free Energy, it is vital that temperature is used correctly in Kelvin units to ensure that the entropy's contribution to abla G is accurately determined. For instance, in our exercise example, the temperature is given at 700 K, which is central to evaluating the reaction's spontaneous nature at this specific state. Its interplay with abla S provides insight into the thermal energy available to increase disorder within the system.

The Gibbs Free Energy equation is the cornerstone for predicting the spontaneity of a chemical reaction. The equation, abla G = abla H - Tabla S, expresses the balance between the enthalpy change (abla H) and the entropy change (abla S) of a reaction, adjusted for the absolute temperature (T) in Kelvin.

If abla G is negative, the reaction is spontaneous, meaning it can occur without external input. A positive abla G implies that the reaction is non-spontaneous under given conditions, and zero abla G indicates a system in equilibrium, where the reaction proceeds in neither direction spontaneously. It is crucial to execute careful unit conversions to ensure accuracy, as we saw in the exercise, converting every parameter to Joules before substituting them into the equation ensures coherence in the calculated value of abla G. Once calculated, the result then often gets converted back to kJ or other units as required for reporting or comparison with standard values.