# Write Mathematical Equation of First Law of Thermodynamics for Isochoric Process - Chemistry

Write mathematical equation of first law of thermodynamics for Isochoric process

#### Solution

By substituting equation W= -p_(ex).triangleV in the equation triangleU=q+W, we get

triangleU=q-p_(ex).triangleV .........(1)

If the reaction is carried out in a closed container so that the volume of the system is constant, thentriangleV=0.In such a case, no work is involved.

The equation (1) becomes triangleU=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.

Concept: Chemical Thermodynamics and Energetic - First Law of Thermodynamics
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