Vapour Pressure Flashcards
What happens to molecules in a closed system containing a liquid and a gas headspace?
A fraction of the molecules will escape the liquid phase and evaporate into the gas phase, establishing an equilibrium vapor pressure.
What is equilibrium vapor pressure?
Equilibrium vapor pressure is the pressure exerted by the vapor in equilibrium with its liquid at a given temperature.
How is equilibrium vapor pressure affected by temperature?
Equilibrium vapor pressure is temperature-dependent; as temperature increases, vapor pressure typically increases due to increased molecular energy.
What role do cohesive forces play in a liquid’s vapor pressure?
Strong cohesive forces, like hydrogen bonds in water, require greater kinetic energy for molecules to escape the liquid phase, resulting in lower vapor pressure.
What is Raoult’s Law?
Raoult’s Law states that the partial pressure of each component in an ideal mixture is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture.
How does adding solute to water affect vapor pressure?
Adding solute lowers the vapor pressure by reducing the surface area available for evaporation and altering the mole fraction of the solvent.
Define the mole fraction in the context of a solution.
The mole fraction is the ratio of the number of moles of a component to the total number of moles of all components in the mixture.
How does Raoult’s Law apply to a solution of sugar in water?
The partial pressure of water in the sugar solution can be calculated as the vapor pressure of pure water multiplied by the mole fraction of water in the solution.
