Question

what is vapour pressure, lowering pressure and relative lowering of vapour pressure?​

Answer 1

Answer:

Explanation:Vapor pressure (or vapour pressure in British spelling) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's evaporation rate. It relates to the tendency of particles to escape from the liquid (or a solid). A substance with a high vapor pressure at normal temperatures is often referred to as volatile. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the kinetic energy of its molecules also increases. As the kinetic energy of the molecules increases, the number of molecules transitioning into a vapor also increases, thereby increasing the vapor pressure.  

Vapor pressure lowering is a colligative property of solutions. The vapor pressure of a pure solvent is greater than the vapor pressure of a solution containing a non volatile liquid. This lowered vapor pressure leads to boiling point elevation.

Relative lowering of vapor pressure. The vapor pressure of a liquid is thepressure of the vapor which is in equilibrium with that liquid. The vaporpressure of a solvent is lowered when a non-volatile solute is dissolved in it to form a solUTION.....

Answer 2

Answer:

(1) Relative vapour pressure of a solution : lf P_0 is the vapour pressure of a pure liquid (solvent) and P is the vapour pressure of a solution after adding a nonvolatile solute, then, relative vapour pressure = P/P_0

(2) Lowering or vapour pressure ot a solution : When a nonvolatile solute is added to a pure solvent, the surface area is covered by the solute molecule decreasing the rate of evaporation, hence its vapour pressure decreases. This decrease in Vapour pressure is called lowering of vapour pressurc.

P_o is the vapour pressure ot a pure solvent (liquid) and Pis the vapour pressure of the solution, where P < Po, then, (P_o-P) is the lowering of the vapour pressure.

3) Relative lowering of vapour pressure : if P_o and P are the respective vapour pressures ot a pure liquid (solvent) and the solution containing a non- volatile solute then P <P_o. Hence, P_o-P represents the lowering of the vapour pressure due to addition of a nonvolatile solute.