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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 Presentation
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Colligative Properties of Diluted Solutions
Raoult
H2O (l) H2O (g) p( )Pa, kPa
pp p p
Raoult
Raoult , p = po xA po:,P:
xA+ xB =1p= po xA = po(1- xB)= po - po xB po- p = po xB p = po- p p = po xB p p0
nA>> nB
1000g
p= K bB
1 C5H12M = 72.15 gmol-120.377.31 kPa0.0697g0.891g2.32 kPaRaoultK
K = p0MAK = p0MA = 77.31 kPa72.15 gmol-1 =5578 kPagmol-1 = 5.578 kPakgmol-1
2 293K2.338 kPa6.840 g(C12H22O11)100.0 g
p = p0xA = 2.338 kPa0.996 4 = 2.330 kPa
101.3kPa
Tb = Tb - Tb0 = Kb mB
T0bKb
273 K
(3)(4)Tf
(a) (b)
Tf = Tf0 - Tf = Kf bB
T0b KbT0f Kf
Kf
0.638 g250 g0.079 K
p = i K bBTb = i Kbb B Tf = i Kfb B ABi2 (KCl) AB2A2B, i3 (MgCl2)
0.100molkg-1NaCl NaClABi =2Tf(NaCl) = 20.100 molkg-11.86 Kkgmol 1 =0.372 K Tf(NaCl) = - 0.372
, ,
: PakPa
= cBRT cB (molL-1) R 8.314 JK-1mol-1 T (273 + t)
cos
303.7 mmolL-1 cos 280 ~ 320 mmolL-1 cos 320 mmol L-1 cos 280 mmolL-1
mmolL-1
mmolL-1
50.0 gL-19.00 gL-1 NaCl() (C6H12O6)180 gmol-1
NaCl58.5 gmol-1