第二章 稀溶液的依数性
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第二章 稀溶液的依数性. Colligative Properties of Diluted Solutions. 内容提要. 溶液的蒸汽压下降 溶液的蒸汽压 溶液的蒸汽压下降 —— Raoult 定律 溶液的沸点升高和凝固点降低 溶液的沸点升高 溶液的凝固点降低. 内容提要. 溶液的渗透压 渗透现象和渗透压 溶液的渗透压力与浓度及温度的关系 渗透压在医学上的意义. 教学基本要求. 了解稀溶液的蒸气压下降、沸点升高、凝固点降低的原因。 熟悉稀溶液的蒸气压下降、沸点升高、凝固点降低概念及计算。 - PowerPoint PPT PresentationTRANSCRIPT
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Colligative Properties of Diluted Solutions
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Raoult
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H2O (l) H2O (g) p( )Pa, kPa
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pp p p
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Raoult
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Raoult , p = po xA po:,P:
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xA+ xB =1p= po xA = po(1- xB)= po - po xB po- p = po xB p = po- p p = po xB p p0
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nA>> nB
1000g
p= K bB
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1 C5H12M = 72.15 gmol-120.377.31 kPa0.0697g0.891g2.32 kPaRaoultK
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K = p0MAK = p0MA = 77.31 kPa72.15 gmol-1 =5578 kPagmol-1 = 5.578 kPakgmol-1
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2 293K2.338 kPa6.840 g(C12H22O11)100.0 g
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p = p0xA = 2.338 kPa0.996 4 = 2.330 kPa
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101.3kPa
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Tb = Tb - Tb0 = Kb mB
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T0bKb
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273 K
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(3)(4)Tf
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(a) (b)
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Tf = Tf0 - Tf = Kf bB
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T0b KbT0f Kf
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Kf
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0.638 g250 g0.079 K
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p = i K bBTb = i Kbb B Tf = i Kfb B ABi2 (KCl) AB2A2B, i3 (MgCl2)
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0.100molkg-1NaCl NaClABi =2Tf(NaCl) = 20.100 molkg-11.86 Kkgmol 1 =0.372 K Tf(NaCl) = - 0.372
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, ,
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: PakPa
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= cBRT cB (molL-1) R 8.314 JK-1mol-1 T (273 + t)
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cos
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303.7 mmolL-1 cos 280 ~ 320 mmolL-1 cos 320 mmol L-1 cos 280 mmolL-1
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mmolL-1
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mmolL-1
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50.0 gL-19.00 gL-1 NaCl() (C6H12O6)180 gmol-1
NaCl58.5 gmol-1