Raoults Law Example Problem - Vapor Pressure Change

Raoult's Law Example Problem - Vapor Pressure Change This model issue shows how to utilize Raoults Law to compute the adjustment in fume pressure by adding a solid electrolyte to a dissolvable. Raoults Law relates the fume weight of an answer on the mole portion of the solute added to a concoction arrangement. Fume Pressure Problem What is the adjustment in fume pressure when 52.9 g of CuCl2 is added to 800 mL of H2O at 52.0  °C.The fume weight of unadulterated H 2O at 52.0  °C is 102.1 torrThe thickness of H2O at 52.0  °C is 0.987 g/mL. Arrangement Using Raoult's Law Raoults Law can be utilized to communicate the fume pressure connections of arrangements containing both unstable and nonvolatile solvents. Raoults Law is communicated byPsolution ÃŽ §solventP0solvent wherePsolution is the fume weight of the solutionî §solvent is mole division of the solventP0solvent is the fume weight of the unadulterated dissolvable Stage 1 Decide the mole division of solutionCuCl2 is a solid electrolyte. It will totally separate into particles in water by the reaction:CuCl2(s) â†' Cu2(aq) 2 Cl-This implies we will have 3 moles of solute included for each mole of CuCl2 added.From the occasional table:Cu 63.55 g/molCl 35.45 g/molmolar weight of CuCl2 63.55 2(35.45) g/molmolar weight of CuCl2 63.55 70.9 g/molmolar weight of CuCl2 134.45 g/molmoles of CuCl2 52.9 g x 1 mol/134.45 gmoles of CuCl2 0.39 molTotal moles of solute 3 x (0.39 mol)Total moles of solute 1.18 molmolar weightwater 2(1)16 g/molmolar weightwater 18 g/moldensitywater masswater/volumewatermasswater densitywater x volumewatermasswater 0.987 g/mL x 800 mLmasswater 789.6 gmoleswater 789.6 g x 1 mol/18 gmoleswater 43.87 molî §solution nwater/(nwater nsolute)î §solution 43.87/(43.87 1.18)î §solution 43.87/45.08î §solution 0.97 ï » ¿Step 2 Discover the fume weight of the solutionPsolution ÃŽ §solventP0solventPsolution 0.97 x 102.1 torrPsolution 99.0 torr ï » ¿Step 3 Discover the adjustment in fume pressureChange in pressure is Pfinal - POChange 99.0 torr - 102.1 torrchange - 3.1 torr Answer The fume weight of the water is decreased by 3.1 torr with the expansion of the CuCl2.