Concept:When heat is transferred to a system, the conditions under which it occurs (constant volume vs. constant pressure) dictate which thermodynamic property changes.
Formula:$$ q_p = \Delta H $$
Solution:- When heat is added at a constant volume (\( q_v \)), all energy goes into changing the internal energy (\( \Delta E \)) because no \( P\Delta V \) work can be done.
- When heat is added at a constant pressure (\( q_p \)), the system is allowed to expand and do work. The total heat added accounts for both the internal energy change and the work done.
- This specific quantity is defined as the change in Enthalpy (H).
Why other options are incorrect:Internal energy equals heat at constant
volume. Heat capacity is the ratio of heat to temperature change. Work done is a separate component (\( P\Delta V \)).
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