Practice Q3 At 250C, PCIs completaly evaporates and then partially dissociates into PCl3 and Cl2o If 2.98 g PCIs is placed in a 1.00 dm container and completely evaporates into gas, the total pressure is 113 kPa. Calculate the partial pressure of each gas component Solution: MWpc5=2085nc5=298/2085=143X102mo When PCls completely evaporates but before dissociation P=nRTN=143X102x8314X(250+27315)/100×103=6214kPa When partially dissociate: PCl5(9)+> PCl3(g)+ CI2(g) 6214-X, Ptotal= PpCi5 PpC3+ Pc12 =6214-X+X+x =113 kPa >X=50.86 kPa So: PPCI5=62.14-x=11.28 kPa, PPC13=PC12=50.86 kPa 11
Practice z Q3: At 250°C, PCl5 completaly evaporates and then partially dissociates into PCl partially dissociates into PCl3 and Cl2。If 2 98 g PCl If 2.98 g PCl5 is placed in a 1.00 dm3 container and completely evaporates into g, p as the total pressure is 113 kPa. Calculate the partial pressure of each gas component. z S l ti o u on: MWPCl5 = 208.5 nPCl5 = 2.98 / 208.5 = 1.43 x 10-2 mol When PCl5 completely evaporates but before dissociation: P = nRT/V = 1.43 x 10-2 x 8.314 x (250 + 273.15) / 1.00 x 10-3 = 62.14 kPa When partially dissociate: PCl ( ) C () C ( ) 5 (g) ↔ PCl3 (g) + Cl2 (g) PPCl5 = 62.14 – x, PPCl3 = x, PCl2 = x Ptotal = PPCl5 + PPCl3 + PCl2 = 62 14 . – x + x + x 113 kPa x + x + x = 113 kPa Æ x 50 86 kPa x = 50.86 kPa So: PPCl5 = 62.14 – x = 11.28 kPa, PPCl3 = PCl2 = 50.86 kPa 11
Phase Phase A material or material fraction with(macroscopically) homogeneous physical chemical properties e.g. Gas, Liquid, (water Vs. oil), Solid, (different solids) ● Phase change A same material changes from one phase to another Phase Equilibrium For a material. when its all fractions of different phases remain unchanged under a certain condition
Phase z Phase A material or material fraction with (macroscopically) homog py p p eneous physical & chemical properties e.g. Gas, Liquid, (water vs. oil), Solid, (different solids) z Phase Change A same material changes from one phase to another. z Ph E ilib i Phase Equilibrium For a material, when its all fractions of different phases remain unchanged under a certain condition. 12
Liquid ● Liquid Liquid is a kind of condensed phase Short-range ordered; Long- range disordered Liquid evaporation above liquid 女9 8B. S Open System Liquid q Molecules with higher energy will escape from liquid phase to vapor phase first
Liquid z Liquid Li id i ki d f "C d d Ph " Liquid is a kind of "Condensed Phase" Short-rang ;g e ordered; Long-range disordered z Liquid Evaporation Vapor：gas molecules above liquid Open Liquid System 13 Molecules with higher energy will escape from liquid phase to vapor phase first