What is the basis of Hess's law of heat summation?

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Hess's Law**: Hess's law of heat summation states that the total enthalpy change during a chemical reaction is the same, regardless of whether the reaction occurs in one step or multiple steps. This means that the enthalpy change for a reaction can be calculated by summing the enthalpy changes of individual steps that lead to the same final state.

2. **Principle of Conservation of Energy**: The basis of Hess's law is rooted in the principle of conservation of energy. According to this principle, energy cannot be created or destroyed; it can only change forms. Therefore, the total energy change (enthalpy change) for a process must be the same regardless of the pathway taken.

3. **Illustration with a Reaction**: Consider a reaction where substance A is converted to substance B. This conversion can occur directly or through one or more intermediate steps. For example:
- Direct conversion: A → B (with enthalpy change ΔH1)
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