Using The Phase Diagram For H2O, Which Of The Following Correctly Describes Water At 100°C And 1 Atm Pressure?A. At The Boiling Point B. Gas C. At The Melting Point D. Liquid

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Understanding the Phase Diagram of Water: A Key to Describing its State at 100°C and 1 atm Pressure

The phase diagram of a substance is a graphical representation of the different phases that it can exist in, as a function of temperature and pressure. For water (H2O), the phase diagram is particularly complex, with three distinct phases: solid (ice), liquid (water), and gas (water vapor). In this article, we will use the phase diagram of water to determine the correct description of water at 100°C and 1 atm pressure.

The phase diagram of water is a plot of temperature against pressure, with the different phases of water represented by different regions. The diagram is divided into three main regions: solid (ice), liquid (water), and gas (water vapor). The boundaries between these regions are defined by the melting and boiling points of water.

Melting Point

The melting point of water is the temperature at which it changes from a solid (ice) to a liquid (water). At standard pressure (1 atm), the melting point of water is 0°C (32°F). Below this temperature, water exists as a solid (ice), while above this temperature, it exists as a liquid (water).

Boiling Point

The boiling point of water is the temperature at which it changes from a liquid (water) to a gas (water vapor). At standard pressure (1 atm), the boiling point of water is 100°C (212°F). Below this temperature, water exists as a liquid (water), while above this temperature, it exists as a gas (water vapor).

The Critical Point

The critical point of water is the temperature and pressure at which the liquid and gas phases become indistinguishable. At this point, the density of the liquid and gas phases is equal, and the distinction between the two phases disappears. The critical point of water is approximately 374°C (675°F) and 221 atm.

Now that we have a basic understanding of the phase diagram of water, we can use it to determine the correct description of water at 100°C and 1 atm pressure.

  • Option A: At the boiling point - This option is correct. At 100°C and 1 atm pressure, water is at its boiling point, and it is changing from a liquid (water) to a gas (water vapor).
  • Option B: Gas - This option is incorrect. While water is at its boiling point, it is not yet a gas. It is still in the process of changing from a liquid to a gas.
  • Option C: At the melting point - This option is incorrect. The melting point of water is 0°C (32°F), which is far below the temperature of 100°C.
  • Option D: Liquid - This option is incorrect. While water is at its boiling point, it is not a liquid. It is changing from a liquid to a gas.

In conclusion, the phase diagram of water is a powerful tool for understanding the different phases that it can exist in, as a function of temperature and pressure. By using the phase diagram, we can determine the correct description of water at 100°C and 1 atm pressure, which is at the boiling point.

  • The phase diagram of water is a graphical representation of the different phases that it can exist in, as a function of temperature and pressure.
  • The melting point of water is 0°C (32°F), while the boiling point is 100°C (212°F).
  • The critical point of water is approximately 374°C (675°F) and 221 atm.
  • At 100°C and 1 atm pressure, water is at its boiling point and is changing from a liquid to a gas.
  • National Institute of Standards and Technology (NIST). (2022). Phase Diagram of Water.
  • International Association for the Properties of Water and Steam (IAPWS). (2016). IAPWS Formulation 2008 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use.
  • CRC Handbook of Chemistry and Physics. (2022). Phase Diagrams of Water.