Q.1 what is the difference between vapour and steam?
Vapour has suspended water particles and vapour exist at temperature below
Q.2 at what pressure critical temperature of mercury is achived?
at atmospheric pressure i.e (pressure at mean sea level is ,1atm or 1 bar) mercury has saturation temperature(boiling temperature) as
Vapour has suspended water particles and vapour exist at temperature below
100°C (Boiling Point of Water), it appears in the form of fog.
-for e.g , vapour coming out of kettle is visible after some gap from outlet.
- it is visible.
Steam do not have water droplets suspended in it. it exists at temperature above
100°C . it is invisible and purely in gas form.
- for e.g steam immidiatly coming after kettle nozzle.
Q.2 at what pressure critical temperature of mercury is achived?
at atmospheric pressure i.e (pressure at mean sea level is ,1atm or 1 bar) mercury has saturation temperature(boiling temperature) as
357°C.
critical temperature ( where gas and liquid properties becomes identical, maximum boiling temperature that can be achived by increasing pressure) is acived is
588.4°C , just slight increase of pressure that is 21 bar abs.
Q.3 why does vapour in wet region should be used in carnot cycle rather than steam?
Carnot cycle gives the highest thermal efficiency which is given by.
Q.3 why does vapour in wet region should be used in carnot cycle rather than steam?
Carnot cycle gives the highest thermal efficiency which is given by.
. To approach this cycle in an actual engine it is necessary that whole of the heat must be supplied at constant temperature T1 and rejected at T2. this can be achived by using vapour in wet field but not in the superheated. the efficiency depends on temperature T1. since T2 is fixed by natural sink to which heat is rejected.this means that T1 should be as large as possible, consistent with the vapour being saturated.
-if we use steam as the working medium the temperature rise can be accopmnied by the pressure rise ant at critical temperature of
-if we use steam as the working medium the temperature rise can be accopmnied by the pressure rise ant at critical temperature of
374°C pressure is as high as 226 bar which will create many difficulties in design, operation and control.
-it is therfore desirable to use some other fluid rather than steam which would have more desirable thermodynamic properties than water. mercury, diphenyl oxide, aluminium bromide , zinc ammonium chloride are the options. mercury is the only working fluid which has been used successfully in practice.
Q.4 what is saturated liquid and saturated vapour?
saturated liquid contains as much as thermal energy as it can without boiling, conversely saturated vapour contains as little thermal energy as it can without condensing.
Q.5 what is saturated temperature?
-Saturation temperature means boiling point.
-The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase. The liquid can be said to be saturated with thermal energy. Any addition of thermal energy results in a phase transition.
-If the pressure in a system remains constant (isobaric), a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy (heat) is removed. Similarly, a liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied.
Q.6 Explain Boiling Point?
The boiling point corresponds to the temperature at which the vapor pressure of the liquid equals the surrounding environmental pressure. Thus, the boiling point is dependent on the pressure. Usually, boiling points are published with respect to atmospheric pressure (101.325 kilopascals or 1 atm). At higher elevations, where the atmospheric pressure is much lower, the boiling point is also lower. The boiling point increases with increased pressure up to the critical point, where the gas and liquid properties become identical. The boiling point cannot be increased beyond the critical point. Likewise, the boiling point decreases with decreasing pressure until the triple point is reached. The boiling point cannot be reduced below the triple point.
If the heat of vaporization and the vapor pressure of a liquid at a certain temperature is known, the normal boiling point can be calculated by using the Clausius-Clapeyron equation thus:
Q.7 Explain saturation pressure?
Saturation pressure is the pressure for a corresponding saturation temperature at which a liquid boils into its vapor phase. Saturation pressure and saturation temperature have a direct relationship: as saturation pressure is increased so is saturation temperature.
If the temperature in a system remains constant (an isothermal system), vapor at saturation pressure and temperature will begin to condense into its liquid phase as the system pressure is increased. Similarly, a liquid at saturation pressure and temperature will tend to flash into its vapor phase as system pressure is decreased.
The boiling point of water is 100 °C (212 °F) at standard pressure. On top of Mount Everest, at 8,848 m (29,029 ft) elevation, the pressure is about 252 Torr (33.597 kPa)[6] and the boiling point of water is 71 °C (159.8 °F). The boiling point decreases 1 °C every 285 m of elevation, or 1 °F every 500 ft.
There are two conventions regarding the standard boiling point of water: The normal boiling point is 99.97 degrees Celsius at a pressure of 1 atm (i.e., 101.325 kPa). Until 1982 this was also the standard boiling point of water, but the IUPAC now recommends a standard pressure of 1 bar (100 kPa).[7] At this slightly reduced pressure, the standard boiling point of water is 99.61 degrees Celsius.[8]
Q.8 explain heat of vaporization?
The heat of vaporization is the energy required to transform a given quantity (a mol, kg, pound, etc.) of a substance from a liquid into a gas at a given pressure (often atmospheric pressure).
Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation. Evaporation is a surface phenomenon in which molecules located near the liquid's edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, resulting in the formation of vapor bubbles within the liquid.
Q.10 why ice is less dense than water?
Ice is less dense than water because as water cools and becomes a solid (freezes), hydrogen bonds form between the water molecules. This is a covalent bond which leads to interconnected solid pattern. There is much more space between each molecule due to Hydrogen Bonds which makes the Ice less denser compared to water.
Q.9 why weight of liquid is less than weight of vapor?
Q.4 what is saturated liquid and saturated vapour?
saturated liquid contains as much as thermal energy as it can without boiling, conversely saturated vapour contains as little thermal energy as it can without condensing.
Q.5 what is saturated temperature?
-Saturation temperature means boiling point.
-The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase. The liquid can be said to be saturated with thermal energy. Any addition of thermal energy results in a phase transition.
-If the pressure in a system remains constant (isobaric), a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy (heat) is removed. Similarly, a liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied.
Q.6 Explain Boiling Point?
The boiling point corresponds to the temperature at which the vapor pressure of the liquid equals the surrounding environmental pressure. Thus, the boiling point is dependent on the pressure. Usually, boiling points are published with respect to atmospheric pressure (101.325 kilopascals or 1 atm). At higher elevations, where the atmospheric pressure is much lower, the boiling point is also lower. The boiling point increases with increased pressure up to the critical point, where the gas and liquid properties become identical. The boiling point cannot be increased beyond the critical point. Likewise, the boiling point decreases with decreasing pressure until the triple point is reached. The boiling point cannot be reduced below the triple point.
If the heat of vaporization and the vapor pressure of a liquid at a certain temperature is known, the normal boiling point can be calculated by using the Clausius-Clapeyron equation thus:
| where: | |
 |
= the normal boiling point, K |
|---|---|
 |
= the ideal gas constant, 8.314 J · K−1 · mol−1 |
 |
= is the vapor pressure at a given temperature, atm |
 |
= the heat of vaporization of the liquid, J/mol |
 |
= the given temperature, K |
 |
= the natural logarithm to the base e |
Q.7 Explain saturation pressure?
Saturation pressure is the pressure for a corresponding saturation temperature at which a liquid boils into its vapor phase. Saturation pressure and saturation temperature have a direct relationship: as saturation pressure is increased so is saturation temperature.
If the temperature in a system remains constant (an isothermal system), vapor at saturation pressure and temperature will begin to condense into its liquid phase as the system pressure is increased. Similarly, a liquid at saturation pressure and temperature will tend to flash into its vapor phase as system pressure is decreased.
The boiling point of water is 100 °C (212 °F) at standard pressure. On top of Mount Everest, at 8,848 m (29,029 ft) elevation, the pressure is about 252 Torr (33.597 kPa)[6] and the boiling point of water is 71 °C (159.8 °F). The boiling point decreases 1 °C every 285 m of elevation, or 1 °F every 500 ft.
There are two conventions regarding the standard boiling point of water: The normal boiling point is 99.97 degrees Celsius at a pressure of 1 atm (i.e., 101.325 kPa). Until 1982 this was also the standard boiling point of water, but the IUPAC now recommends a standard pressure of 1 bar (100 kPa).[7] At this slightly reduced pressure, the standard boiling point of water is 99.61 degrees Celsius.[8]
Q.8 explain heat of vaporization?
The heat of vaporization is the energy required to transform a given quantity (a mol, kg, pound, etc.) of a substance from a liquid into a gas at a given pressure (often atmospheric pressure).
Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation. Evaporation is a surface phenomenon in which molecules located near the liquid's edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, resulting in the formation of vapor bubbles within the liquid.
Q.10 why ice is less dense than water?
Ice is less dense than water because as water cools and becomes a solid (freezes), hydrogen bonds form between the water molecules. This is a covalent bond which leads to interconnected solid pattern. There is much more space between each molecule due to Hydrogen Bonds which makes the Ice less denser compared to water.
Q.9 why weight of liquid is less than weight of vapor?
