Water at 7 bar and 120°C is
a) subcooled liquid
in a state of
b) superheated vapor
c) two-phase mixture
d) undetermined
The correct answer and explanation is :
The correct answer is a) subcooled liquid.
Explanation:
To determine the state of water at 7 bar and 120°C, we need to compare the given conditions to the thermodynamic properties of water at the same pressure and temperature.
- Identify the Saturation Temperature at 7 bar:
The saturation temperature is the temperature at which water boils (or condenses) at a specific pressure. For water at 7 bar, the saturation temperature is approximately 158.83°C. This means that at 7 bar, water boils (transitions from liquid to vapor) at 158.83°C. - Comparison of Temperature with Saturation Temperature:
The given temperature of the water is 120°C, which is below the saturation temperature of 158.83°C at 7 bar. Since the temperature is below the boiling point, the water is in a liquid state. - Subcooled Liquid State:
When water is at a temperature below its saturation temperature at a given pressure, it is considered a subcooled liquid. In this case, since the temperature (120°C) is lower than the saturation temperature (158.83°C) at 7 bar, the water is indeed a subcooled liquid. - Why not the Other Choices?
- b) Superheated Vapor: Superheated vapor refers to a state where the temperature is above the saturation temperature for a given pressure, which is not the case here. The temperature of 120°C is below the saturation temperature at 7 bar, so it cannot be superheated vapor.
- c) Two-phase mixture: A two-phase mixture occurs when the substance exists as a mixture of both liquid and vapor (i.e., at the saturation temperature and pressure). Since the temperature is below the saturation temperature, we do not have a mixture of liquid and vapor.
- d) Undetermined: We can clearly determine the state based on the temperature and pressure, so “undetermined” is not applicable.
Thus, the correct answer is subcooled liquid.