Question

One pound-mass of water fills a container whose volume is 2 ft³. The pressure in the container is 100 psia. Calculate the total internal energy and enthalpy in the container

Answer 1

The total internal energy in the container is -477,704.59 J and the enthalpy is -473,764.92 J.

Step-by-step explanation:

To calculate the total internal energy and enthalpy in the container, we need to use the equation U = mcΔT and H = U + PV, where U is the internal energy, m is the mass, c is the specific heat capacity, ΔT is the change in temperature, H is the enthalpy, P is the pressure, and V is the volume.

First, we need to convert the volume from cubic feet to cubic meters. Since 1 cubic meter is equal to 35.3147 cubic feet, the volume of the container is 2 ft³ * 0.0283168 m³/ft³ = 0.0566336 m³.

Using the given values, the mass of the water is 1 lb-mass, the specific heat capacity of water is 4.186 J/g°C, and the change in temperature is ΔT = 0 - 25 °C = -25 °C.

Now we can calculate the internal energy:

U = mcΔT = (453.592 g)(4.186 J/g°C)(-25 °C) = -477,704.59 J

Finally, we can calculate the enthalpy:

H = U + PV = -477,704.59 J + (100 psia)(6.89476 kPa/psia)(0.0566336 m³) = -477,704.59 J + 3,939.67 J = -473,764.92 J