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Questions
Write mathematical equation of first law of thermodynamics for Isochoric process.
Deduce first law of thermodynamics for isochoric process.
Solution
By substituting equation `W = - p_(ex).triangleV` in the equation `triangle U = q + W`, we get
`triangle U = q - p_(ex).triangle V ...(1)`
If the reaction is carried out in a closed container so that the volume of the system is constant, then `triangle V = 0.` In such a case, no work is involved.
The equation (1) becomes `triangle U = q_v`
Equation (1) suggests that the change in internal energy of the system is due to heat transfer. The subscript v indicates a constant volume process. As U is a state function, qv is also a state function. We see that an increase in the internal energy of a system is numerically equal to the heat absorbed by the system in a constant volume (isochoric) process.
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