Final answer:
The triple point of a substance is where its solid, liquid, and gas phases coexist in equilibrium at a specific temperature and pressure; for water, this is at 273.16 K and 0.6117 kPa.
Step-by-step explanation:
The triple point of a substance is the unique combination of temperature and pressure at which the solid, liquid, and gas phases of that substance exist in equilibrium simultaneously. For water, this occurs at 273.16 K and 0.6117 kPa. At the triple point, all three states are equally stable and can coexist. Therefore, the triple point can be depicted on a phase diagram, where the solid/liquid, liquid/gas, and solid/gas lines intersect. In a phase diagram, the triple point represents the only set temperature and pressure condition at which the three phases can exist in equilibrium together. This concept is vital in thermodynamics and also serves as a calibration point for temperature measurements, as it is a more accurate standard than the melting point of ice at 1 atm.
The triple point is the temperature and pressure at which a substance exists in equilibrium as a solid, liquid, and gas. It is the point in a phase diagram where the solid/liquid, liquid/gas, and solid/gas lines intersect. At the triple point, all three phases can coexist simultaneously.
For water, the triple point occurs at 273.16 K (0.01°C) and 0.6117 kPa. This is a more accurate calibration temperature than the melting point of water at 1.00 atm, or 273.15 K (0.0°C). The triple point represents the only combination of temperature and pressure where all three phases are in equilibrium.