Problem 31 - Chemistry: An Atoms-Focused Approach

Question

What is meant by an entbalpy change?

Step-by-Step Solution

Answer

Answer: Enthalpy change is the difference in the total energy of a system before and after a thermodynamic process. It is significant in chemistry because it helps in determining whether a chemical reaction is exothermic (releases energy) or endothermic (absorbs energy). This information is crucial in understanding the behavior of chemical reactions.

Step 1: Define enthalpy change

Enthalpy (H) is a thermodynamic property that represents the total energy of a system, including its internal energy and work done by the system against external pressure. Enthalpy change (∆H) is the difference in enthalpy between the final state and the initial state of a system for any given thermodynamic process.

Step 2: Understand the significance of enthalpy change in chemistry

Enthalpy change is an essential concept in chemistry, particularly in the study of chemical reactions. It helps us to determine whether a reaction is exothermic (releases energy) or endothermic (absorbs energy). In an exothermic reaction, the enthalpy change is negative (∆H < 0), and heat is released to the surroundings. Meanwhile, in an endothermic reaction the enthalpy change is positive (∆H > 0), and heat is absorbed from the surroundings.

Step 3: Derive the equation for enthalpy change

The equation for enthalpy change (∆H) can be derived from the definition of enthalpy. Suppose we have a system with initial enthalpy (H1) and it undergoes a thermodynamic process until it reaches its final state with enthalpy (H2). The enthalpy change is given by: ∆H = H2 - H1 Where ∆H represents the enthalpy change, H2 is the final enthalpy, and H1 is the initial enthalpy of the system. In conclusion, enthalpy change is the difference in the total energy of a system before and after a thermodynamic process, which is crucial in understanding the behavior of chemical reactions and determining whether they are exothermic or endothermic.