Phase Diagrams of Water & CO2 Explained - Chemistry - Melting, Boiling & Critical Point

The Organic Chemistry Tutor2 minutes read

Phase changes involve terms like melting, freezing, vaporization, condensation, sublimation, and deposition, as seen in the CO2 phase diagram with unique characteristics like sublimation and the critical point. The phase diagram for water differs from CO2, with a negative slope for the melting point line, allowing all phases at one atm pressure, and liquid water having a higher density than ice.

Insights

  • Different substances undergo phase changes with specific terms like melting, freezing, vaporization, condensation, sublimation, and deposition.
  • The phase diagrams of CO2 and water illustrate unique characteristics such as the triple point, critical point, and density differences between phases, showcasing the complex relationships between temperature, pressure, and state changes in these substances.

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Recent questions

  • What are the different phase changes?

    Melting, freezing, vaporization, condensation, sublimation, deposition.

  • What is the triple point in a phase diagram?

    Point where solid, liquid, and gas coexist.

  • How does CO2 transition from solid to gas?

    Sublimes directly due to pressure below triple point.

  • What is the critical point in a phase diagram?

    Boundary for supercritical fluid.

  • How does the phase diagram of water differ from CO2?

    Water has negative slope for melting point line.

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Summary

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Phase changes and phase diagrams explained.

  • Phase changes involve specific terms: melting (solid to liquid), freezing (liquid to solid), vaporization (liquid to gas), condensation (gas to liquid), sublimation (solid to gas), and deposition (gas to solid).
  • The phase diagram for CO2 shows the triple point where solid, liquid, and gas phases coexist, the melting point line between solid and liquid phases, and the boiling point curve between liquid and gas phases.
  • CO2 sublimes directly from solid to gas at one atm due to pressure being below the triple point, with solid CO2 having a higher density than liquid CO2 at higher pressures.
  • The critical point marks the boundary for supercritical fluid, possessing properties of both gas and liquid, beyond which a gas cannot be liquefied by increasing pressure.
  • The phase diagram for water differs from CO2 with a negative slope for the melting point line, allowing for all three phases at one atm pressure, and liquid water having a higher density than ice, leading to ice floating on water.
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