A state where all the phase of water can simultaneously co-exist is called _________.
triple point line
Understanding the Triple Point of Water
The question asks about a specific state where all three phases of water – solid, liquid, and gas – can exist together at the same time in equilibrium. This is a unique point on the phase diagram of a substance.
Exploring the Options
Let's look at the given options and understand what each one represents:
- critical state: The critical point is where the liquid and gas phases of a substance become indistinguishable. Above the critical temperature and pressure, the substance exists as a supercritical fluid, not separate liquid and gas phases. Therefore, it is not a state where all three phases coexist.
- saturated liquid line: This line on a phase diagram represents the boundary between the liquid phase and the liquid-vapor equilibrium region. Along this line, a substance is a saturated liquid, meaning it is at its boiling point for that pressure. It does not represent the coexistence of solid, liquid, and gas.
- saturated vapour line: This line on a phase diagram represents the boundary between the vapor (gas) phase and the liquid-vapor equilibrium region. Along this line, a substance is a saturated vapor, meaning it is at its condensation point for that pressure. It does not represent the coexistence of solid, liquid, and gas.
- triple point line: The triple point is a specific temperature and pressure at which the solid, liquid, and gaseous phases of a substance coexist in thermodynamic equilibrium. For water, this occurs at a temperature of 0.01 °C (273.16 K) and a pressure of 611.657 Pascals (approximately 0.006 atm). This is precisely the state described in the question.
The Triple Point Explained
The triple point is a single point on the phase diagram because it represents a specific, unique combination of temperature and pressure where the three phase boundaries meet. At this precise condition, solid water (ice), liquid water, and water vapor (gas) can all exist alongside each other in a stable state.
Consider the phase diagram of water:
| Phase | Condition at Triple Point |
|---|---|
| Solid (Ice) | Can coexist in equilibrium at the triple point temperature and pressure. |
| Liquid (Water) | |
| Gas (Water Vapor) |
Any slight change in temperature or pressure from the triple point will cause one or more of the phases to disappear as the system moves into a region on the phase diagram where only one or two phases are stable.
Conclusion
The state where all three phases of water can simultaneously coexist is known as the triple point. Therefore, the correct option is the one referring to the triple point.
Important Questions from Phase Change of a Pure Substance
The critical temperature of water in degrees is:
Which of the following statements is true about sensible heat?
Sensible heat is the heat needed to
The saturation temperature of steam with increase in pressure increases _________.
At a certain point on the phase diagram of a Substance, the liquid and vapor phases become indistinguishable. What is this point called?
