What is meant by saturation vapour pressure of water at 60c is 149.9mmHg
The saturation vapor pressure of water at a specific temperature refers to the maximum pressure that water vapor can exert when it is in equilibrium with liquid water at that temperature. In this case, at 60 degrees Celsius, the saturation vapor pressure of water is 149.9 mmHg.
To understand how this value is determined, we can look at the concept of vapor pressure. When a liquid is in a closed system, some of its molecules have enough energy to escape from the liquid phase and become vapor or gas. These molecules exert a force on the walls of the container, creating a vapor pressure.
At higher temperatures, more molecules have sufficient energy to escape, thereby increasing the vapor pressure. When the vapor pressure reaches a certain value at a particular temperature, it becomes equal to the pressure exerted on the surface of the liquid. This is known as the saturation vapor pressure.
To determine the specific value of the saturation vapor pressure at different temperatures, experimental measurements are conducted. Scientists use various methods, such as using a known amount of water in a closed system and measuring the pressure exerted by the vapor phase at different temperatures.
In this case, experiments and calculations have determined that at 60 degrees Celsius, the saturation vapor pressure of water is precisely 149.9 mmHg. This means that in a closed system at this temperature, the pressure exerted by the water vapor will be up to 149.9 mmHg before it condenses back into liquid water.