With the help of first law of thermodynamics and the definition H = E

1.	With the help of first law of thermodynamics and the definition H = E + pV, prove that ΔH = qP.
Answer» The enthalpy is defined by H = E + pV for a change in the states of system ΔH = Δ (E + pV) = ΔE + Δ (pV) = ΔE + pΔV + VΔp ....(i) 1st law of thermodynamics states that ΔE = q + W = q - pΔV ....(ii) From equations (i) and (ii) ΔH = q - pΔV + pΔV + VΔp = q + VΔp When the pressure is constant, Δp = 0, and thus VΔp = 0, therefore ΔH = q (at constant pressure) or, ΔH = q_P

With the help of first law of thermodynamics and the definition H = E + pV, prove that ΔH = qP.

Answer»

The enthalpy is defined by H = E + pV for a change in the states of system

ΔH = Δ (E + pV)

= ΔE + Δ (pV)

= ΔE + pΔV + VΔp ....(i)

1st law of thermodynamics states that

ΔE = q + W

= q - pΔV ....(ii)

From equations (i) and (ii)

ΔH = q - pΔV + pΔV + VΔp

= q + VΔp

When the pressure is constant, Δp = 0, and thus VΔp = 0, therefore

ΔH = q (at constant pressure)

or, ΔH = q_P

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With the help of first law of thermodynamics and the definition H = E + pV, prove that ΔH = qP.

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