Question
Download Solution PDFThe first law of thermodynamics in an isothermal process is represented by- (ΔQ = heat exchanged, Δ W = work done, and ΔU = Internal energy change).
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFCONCEPT:
- The first law of thermodynamics is a restatement of the law of conservation of energy. It states that energy cannot be created or destroyed in an isolated system; energy can only be transferred or changed from one form to another.
- When heat energy is supplied to a thermodynamic system or any machine: Two things may occur:
- The internal energy of the System or machine may change.
- The system may do some external work.
According to the first law of Thermodynamics:
ΔQ = ΔW + ΔU
Where ΔQ = Heat supplied to the system, ΔW = work done by the system, ΔU = change in internal energy of the system
- Isothermal process: When a thermodynamic system undergoes a physical change in such a way that its temperature remains constant, then the change is known as an isothermal process.
Change in temperature = ΔT = 0
The change in internal energy (ΔU) is given by:
ΔU = n Cv ΔT
Where Cv = molar specific heat capacity at the constant volume, n is the number of moles
EXPLANATION:
In an isothermal process,
ΔT = 0
ΔU = n Cv ΔT = 0
According to the first law of Thermodynamics:
ΔQ = ΔW + ΔU
ΔQ = ΔW + 0
Hence ΔQ = ΔW
So option 4 is correct.
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