Concept:According to the first law of thermodynamics, heat transferred to a system can either change its internal energy or perform pressure-volume work.
Formula:$$ q_p = \Delta E + P\Delta V = \Delta H $$
Solution:- When heat (q) is supplied to a system at constant pressure, the system may expand, doing work (\( P\Delta V \)).
- The total heat absorbed accounts for both the change in internal energy (\( \Delta E \)) and the expansion work.
- This specific quantity (\( q_p \)) is defined thermodynamically as the change in Enthalpy (\( \Delta H \)).
Why other options are incorrect:Internal energy (\( \Delta E \)) equals the thermal energy at constant
volume (\( q_v \)), not pressure. Heat capacity is the ratio of heat added to temperature change, not the thermal energy itself.
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