What is ill-saturated vapour pressure of a liquid?

Answer 1

The vapour pressure of a substance is related to how fast it is evaporating. Vapour pressure varies directly with temperature. The hotter it is, the higher the vapour pressure. A substance boils when the vapour pressure of the liquid equals atmospheric pressure pushing down on the substance: usually taken to be 760 mm Hg or 101 kPa. If you know the vapour pressure of a substance you can estimate how much of that substance would be in air above the substance if you put it in a closed room and allowed it to equilibrate. This is called the saturated vapour concentration. If you know for instance that the lower flammable limit of the substance is 0.5% (1% = 10,000 ppm), you would be concerned about the potential for fire if the saturated vapour concentration was greater than 5000 ppm at room temperature. Without ventilation, there would be enough of the substance in air to ignite if there is a source of ignition. In a similar way, if the allowable exposure limit for the substance was an 8-hour time-weighted average of 500 ppm, you would know that it is possible to be overexposed to the substance by inhalation if the saturated vapour concentration exceeds 500 ppm. Estimate the saturated vapour concentration (SVC) using the following formula: SVC = [(vapour pressure of substance in mm Hg)/ 760 mm Hg] X 10^6 Ed Gatey BSc (Chem), CRSP, CIH

Answer 2

The ill-saturated vapor pressure of a liquid is the pressure exerted by the vapor in equilibrium with its liquid at a temperature lower than its normal boiling point. It is a state where the liquid and vapor phases are not in their usual equilibrium state due to a temperature differential.

Answer 3

The Saturated Vapour Pressure of Water at 21 Celsius is

0.02485 Bar

2485 Pa

0.365 Psi

at 0.365 Psi, the water is likely to boil at 21 Celsius.