Question

What is the difference between $\mathbf{∆}\mathbf{H}$and $\mathbf{∆}\mathit{E}$at constant P?

Short answer

$∆H=∆E+P∆V$

At Constant P, the difference between$∆H$ and $∆E$is the quantity $P∆V$.

Step-by-step solution

Enthalpy

Definition of Enthalpy: Enthalpy, a property of a thermodynamic system, is the sum of the system’s internal energy and the product of its pressure and volume.

$∆H=∆E+P∆V$

When a system at constant P can do pressure-volume work, then $∆H$is not equal to $∆E$. When the system cannot do PV work, then $∆H=∆E$at constant pressure.

Heat Flow

The heat flow by a system at constant pressure equals ∆Hand the heat flow by a system at constant volume equals $∆E$.