Concept:Enthalpy (\( H \)) is defined as the internal energy (\( E \)) plus the product of pressure and volume (\( PV \)). For chemical processes, the change in enthalpy relates to the change in internal energy and volume.
Formula:$$ \Delta H = \Delta E + P\Delta V $$
Solution:- When a reaction involves strictly solids and liquids, the change in volume (\( \Delta V \)) is extremely negligible because condensed phases are virtually incompressible.
- Therefore, the term \( P\Delta V \) approaches zero.
- Substituting this into the equation yields: \( \Delta H = \Delta E + 0 \).
- Thus, for solids and liquids, the enthalpy change is approximately equal to the internal energy change: \( \Delta H \approx \Delta E \).
Why other options are incorrect:Option A is the general formula for all states (including gases). Options C and D are mathematically incorrect simplifications that ignore the massive internal energy component.
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