Mechanical Shift-I
water-is-about-to-vapourize-iti
When water is about to vapourize it is called?
Sub-cooled liquid
Super-heated vapour
Saturated vapour
Saturated liquid
The correct answer is No. 4: Saturated liquid
When water is about to vapourize it is called Saturated liquid.
A saturated liquid is defined as a liquid that is in equilibrium with its own vapor at a specified temperature or pressure.
In other words, a liquid that is about to vaporize is called saturated liquid. At boiling point, a liquid is always saturated.
For example, water boils at 100°C, and a standard atmospheric pressure of 101.32 kPa or 1 atm and produces vapor. Under this condition, water is a saturated liquid.
Due to an increase in temperature, the liquid will expand slightly, which in turn will increase the specific volume.
Since the process takes place in the cylinder-piston device, then on expansion the piston will move up slightly.
During this process, the pressure inside the cylinder will remain constant at 1 atm.
At this condition too, water is a compressed liquid as its vaporization is yet to take place. On further heating, the temperature of the water will go on increasing and it reaches 100°C.
At this stage, the water is still in the liquid phase and further addition of heat will cause some of the liquid to vaporize.
It necessarily means that a phase change will take place from liquid to vapor. At this stage, the liquid is known as the saturated liquid.
From the above dome G-H-D:
G-H = saturated liquid line
H-D = saturated vapor line
H = critical point where saturated liquid and saturated vapor lines meet
The region to the left of the G-H curve is called the sub-cooled region
The region to the right of the H-D curve is called the superheated region
?∴ The water which is about to vaporize is called Saturated liquid