Intermediate Topic 379 of 1102 Thermodynamics & Energetics
Isochoric Process
A change at constant volume where no pressure-volume work is done.
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In-depth explanation of Isochoric Process
An isochoric process occurs at constant volume, so no pressure-volume work is done because the system does not expand or contract. Under these conditions the heat exchanged equals the change in internal energy, q equal to delta U, which is why constant-volume calorimetry such as bomb calorimetry directly measures internal energy. Heating a gas in a rigid container is an isochoric process, and its pressure rises with temperature as a result. This situation is typical of sealed reaction vessels and of gas in a rigid tank. Recognizing the constant-volume constraint helps relate heat to changes in internal energy.
Going deeper: Isochoric Process
Key ideas: With volume fixed, w equals zero, q equals delta U equals n Cv delta T for an ideal gas, and pressure rises in proportion to temperature, as stated by Gay-Lussac's law. Sealed vessels, such as pressure cookers and bomb calorimeters, work this way.
Common mistakes and connections: A frequent mistake is to use Cp, or to say that no energy changes when volume is constant. The internal energy changes by the heat supplied. Isochoric analysis supports the definition of Cv and the interpretation of bomb calorimeter data.
Visualization of Isochoric Process
At constant volume no P-V work is done, so heat added raises internal energy directly and pressure climbs in proportion to temperature. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Heating one mole of an ideal gas in a sealed steel tank from 300 K to 600 K doubles its pressure while doing no pressure-volume work.
Frequently asked questions about Isochoric Process
What is Isochoric Process?
A change at constant volume where no pressure-volume work is done.
Is Isochoric Process a beginner, intermediate or advanced topic?
Isochoric Process is a intermediate topic in Thermodynamics & Energetics. It builds on the vocabulary of beginner topics in this area.
What should I learn before Isochoric Process?
Study these earlier topics in Thermodynamics & Energetics first: Isothermal Process, Adiabatic Process, Isobaric Process.
What comes after Isochoric Process?
The next topics in Thermodynamics & Energetics are Cp and Cv and Heat Capacity Ratio.
Can I practise Isochoric Process with quizzes?
Yes. The interactive lesson includes a self-check question on Isochoric Process, and the Thermodynamics & Energetics quiz draws on every topic in this area.
Where Isochoric Process fits in Thermodynamics & Energetics
Isochoric Process is topic 51 of 91 in Thermodynamics & Energetics.