Calculate the change in the enthalpy of argon, in kJ/kg, when it is cooled from 75 to 35°C. If neon had under-gone this same change of temperature, would its enthalpy change have been any different?

Enthalpy almost doubles.

Explanation:

Argon

Cp = Specific heat at constant volume = 0.520 kJ/kgK

T₁ = Initial temperature = 75°C

T₂ = Final temperature = 35°C

Enthalpy

Δh = CpΔT

⇒Δh = Cp (T₂-T₁)

⇒Δh = 0.520 * (35-75)

⇒Δh = - 20.8 kJ/kg

Neon

Cp = Specific heat at constant volume = 1.03 kJ/kgK

T₁ = Initial temperature = 75°C

T₂ = Final temperature = 35°C

Δh = Cp (T₂-T₁)

⇒Δh = 1.03 * (35-75)

⇒Δh = - 41.2 kJ/kg

Enthalpy will change because Cp value is differrent.

Enthalpy almost doubles.