The figure shows the pV diagram for a certain thermodynamic process. In this pro

Question

The figure shows the pV diagram for a certain thermodynamic process. In this process, 1920 J of heat flows into a system, and at the same time the system expands against a constant external pressure of 9 x 10^4 Pa. If the volume of the system increases from 0.020 m^3 to 8x10^-2 m^3, calculate the change in internal (thermal) energy of the system. If the internal (thermal) energy change is nonzero, be sure to indicate whether this energy change is positive or negative. Follow up: Assume that 2 mols of H_2gas undergoes the process (a->b->c) described above. What is the initial temperature of the gas (T_a)? (The molar specific heat of gas along the constant pressure and constant volume portions of the cycle are C_p=28.7 J/mol K and C_v=20.4 J/mol K respectively.)

Explanation / Answer

dQ = dU +pdV

Here P is 9*10^4 Pa

dV is change in Volume = 0.08-0.02 = 0.06 m3

dQ = dU+9*10^4 Pa*0.06 m3

1920J = dU+9*10^4 Pa*0.06 m3

1920 J = dU +5400

So, dU = 1920-5400

dU = -3480 J

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.