4.9.8

Non-Flow Processes

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Isothermal and adiabatic processes

If a gas expands at a constant temperature it is isothermal, if it expands with no heat transfer it is adiabatic.

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Isothermal

  • If a gas expands at a constant temperature it is isothermal.
  • An isothermal line on a pressure-volume graph is a curved line of constant temperature.
  • The product of the pressure and the volume is a constant.
    • pV=constantpV=constant
Illustrative background for Adiabatic Illustrative background for Adiabatic  ?? "content

Adiabatic

  • If a gas expands with no heat transfer it is adiabatic.
  • This means the first law becomes:
    • ΔU=W{\Delta}U= W
  • The condition for an adiabatic expansion is:
    • pVγ=constantpV^{\gamma}= constant
  • Where γ\gamma is a constant.

Constant pressure and volume

Gasses can expand or be compressed under constant pressure or volume.

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Constant pressure

  • At constant pressure, the work done by a gas is given by the pressure multiplied by the change in volume. The equation for work done is:
    • Work done = pressure x change in volume
    • W=pΔVW=p{\Delta}V
  • Work done is measured in Joules.
Illustrative background for Constant volume  Illustrative background for Constant volume   ?? "content

Constant volume

  • If a gas is acted on at a constant volume no work is done as ΔV{\Delta}V = 0.

Jump to other topics

1Principles of Science I

1.1Structure & Bonding

1.2Properties of Substances

1.3Cell Structure & Function

1.4Cell Specialisation

1.5Tissue Structure & Function

1.6Working with Waves

1.7Waves in Communication

2Practical Scientific Procedures and Techniques

3Science Investigation Skills

4Principles of Science II

4.1Extracting Elements

4.2Relating Properties to use of Substances

4.3Organic Chemistry

4.4Energy Changes in Industry

4.5The Circulatory System

4.6Ventilation & Gas Exchange

4.7Urinary System

4.8Cell Transport

4.9Thermal Physics

4.10Materials

4.11Fluids

5Contemporary Issues in Science

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