What Is Vapour Pressure?

1.	What Is Vapour Pressure?
Answer» The terms vapour PRESSURE applies to a liquid, and is the natural equilibrium pressure that exists inside a closed vessel CONTAINING the liquid. Vapour pressure varies with temperature. The vapour pressure of WATER at ambient temperature of about 25°C is in the order of 4 kPa(a). This means that water will boil at 25°C if the external pressure is reduced to an absolute pressure of 4 kPa. At 100°C the vapour pressure of water is 101 kPa(a), which means that water will boil at 100° C at sea LEVEL where the ATMOSPHERIC pressure is about 101 kPa(a).

Answer»

The terms vapour PRESSURE applies to a liquid, and is the natural equilibrium pressure that exists inside a closed vessel CONTAINING the liquid.
Vapour pressure varies with temperature.
The vapour pressure of WATER at ambient temperature of about 25°C is in the order of 4 kPa(a). This means that water will boil at 25°C if the external pressure is reduced to an absolute pressure of 4 kPa. At 100°C the vapour pressure of water is 101 kPa(a), which means that water will boil at 100° C at sea LEVEL where the ATMOSPHERIC pressure is about 101 kPa(a).

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