The balloon portion of a dirigible is filled with 5000 moles of helium (Figure 2-13). Initially, the helium is at P = 1 atm and T = 25°C. As the dirigible gains altitude, the pressure drops to P = 0.95 atm, and the temperature drops to T = 15°C. Find the changes in volume, internal energy, and enthalpy for the helium in this process, assuming helium has a constant ideal gas heat capacity of C*_V = (1.5)R.

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N = 5000 moles of He; P₂ = 0.95 atm; T₂ = 15°C N = 5000 moles of He; P₁ = 1 atm; T₁ = 25°C FIGURE 2-13 Schematic of system in Example 2-4.