a cylinder filled with a movable Piston contains liquid water in equilibrium water vapour at 25 degree Celsius which one of the following operations result in a decrease in equilibrium vapour pressure
Dissolve salt in water
Since the vapour pressure depends on surface area, therefore when the surface area is more,vapour pressure will be more. When we add solute,what we do is we decrease the vapour pressure of solvent because some of the salt ions will be present at the solvent surface,thus taking place of some of the solvent particles which were actively participating in maintaing that previous high value of vapour pressure.so the equlibrium vapour pressure value decreases.
Hmmm. Choices?
lower temperature?
To determine which operation will result in a decrease in equilibrium vapor pressure in a cylinder filled with a movable piston containing liquid water and water vapor at 25 degrees Celsius, we need to understand the factors that affect vapor pressure.
Vapor pressure is the pressure exerted by the vapor in equilibrium with its liquid phase at a given temperature. It depends on the temperature and the nature of the substance. In the case of water, as the temperature increases, the vapor pressure also increases.
Now, let's consider the operations that could potentially decrease the equilibrium vapor pressure:
1. Decreasing the temperature: When the temperature decreases, the kinetic energy of the water molecules decreases, leading to a decrease in the vapor pressure. Therefore, if you cool down the system, the equilibrium vapor pressure will decrease.
2. Removing some water vapor: If you remove some water vapor from the cylinder, it will reduce the number of water molecules in the gas phase. As a result, the equilibrium vapor pressure will decrease since there are fewer molecules available to exert pressure.
3. Decreasing the volume of the cylinder: If you compress the cylinder by moving the piston, you increase the pressure inside the cylinder. This increase in pressure will result in more water molecules condensing from the gas phase to the liquid phase, leading to a decrease in the equilibrium vapor pressure.
Based on these considerations, the operation that will result in a decrease in equilibrium vapor pressure is decreasing the temperature. Cooling down the system will reduce the kinetic energy of the water molecules, causing a decrease in the equilibrium vapor pressure.