Chapter 4 Acid-Base EquilibriaThree issues:溶液理论Acid-BaseTheoryAcid-BaseEquilibria
1 Chapter 4 Acid-Base Equilibria Three issues： 溶液理论 Acid-Base Theory Acid-Base Equilibria
1. Solutions1.1 Concentration unitsno.moles soluteM(1) Molarity (M)no.liters solutionno.moles solute(2) Molality (m)m :no.kiligra ms solvent
2 1. Solutions 1.1 Concentration units no.liters solution no.moles solute (1) Molarity (M) M = (2) Molality (m) no.kiligra ms solvent no.moles solute m =
(3) Mole fraction (X)no.moles AXAtotal no.moles all componentsXa+Xp +... =1
3 (3) Mole fraction (X) total no.moles all components no.moles A XA = XA +XB + . = 1
1-2 Colligative properties of nonelectrolyte solutionsThose solution properties which depend primarily on theconcentration of solute particles rather than their nature arecalledcolligativeproperties(依数性）.Fourphysicalpropertiesof solutions are the same for all nonvolatile solutes:vaporpressureloweringboilingpointelevationfreezingpointdepression·osmoticpressure
4 1-2 Colligative properties of nonelectrolyte solutions Those solution properties which depend primarily on the concentration of solute particles rather than their nature are called colligative properties(依数性). Four physical properties of solutions are the same for all nonvolatile solutes: •vapor pressure lowering •boiling point elevation •freezing point depression •osmotic pressure
760WaterSolutionIceBoilingFreezingpointpointloweringelevationA0B100Temperature,C
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(1) Vapor pressure loweringP =PoXA=P^°(1-XB)在一定温度下，稀溶液的蒸气压等与纯溶液的蒸气压与溶剂摩尔数的乘积
6 (1) Vapor pressure lowering “在一定温度下，稀溶液的蒸气压等与纯溶 液的蒸气压与溶剂摩尔数的乘积。” P = PA 0XA = PA 0 (1-XB )
(2) Boiling point elevationT△T,=T溶液=K,xm溶剂m:溶液的质量摩尔浓度单位：molkglKb:溶剂的沸点上升常数,单位K·kg:mol-1是溶质的质量摩尔浓度为1mol·kg-l 时所引起的溶液沸点上升的数值
7 (2) Boiling point elevation ΔTb= T溶液-T溶剂 =Kb m m:溶液的质量摩尔浓度单位：mol·kg-1 , Kb :溶剂的沸点上升常数,单位K·kg·mol-1 , 是溶质的质量摩尔浓度为1mol·kg-1 时所引 起的溶液沸点上升的数值
(3)Freezingpointdepression△T=TTr溶剂-T 溶液=K,× mK：溶剂的摩尔凝固点下降常数，单位K·kg:mol-l，即m= 1mol·kg-l时所引起的溶液凝固点的下降值。例如：K（H20)=1.68K·kg:mol-1
8 (3) Freezing point depression ΔTf=Tf溶剂-Tf溶液=Kf m Kf：溶剂的摩尔凝固点下降常数，单位 K·kg·mol-1 , 即m= 1mol·kg-1时所引起的溶液凝固 点的下降值。例如：Kf（H2O）=1.68 K·kg·mol-1
例：汽车的散热冷却水，冬季加入乙二醇(或甲醇甘油），可防止结冻，冻裂水箱。求：在1kg水中，加入甘油989g，可使溶液的凝固点下降多少度？（甘油的分子量：Mc3H803=92g/mol)解：△T=K×mK (H20) =1.86 K-kg:mol-1m=(989= 92) / 1kg =10.75mol·kg: △T=1.86 × 10.75=20(K)△T =273- Tr溶液:.T溶液=253K
9 例：汽车的散热冷却水，冬季加入乙二醇(或甲醇⁄甘 油），可防止结冻，冻裂水箱。求：在1kg水中，加 入甘油989g，可使溶液的凝固点下降多少度？（甘油 的分子量：MC3H8O3 = 92g /mol） 解：ΔTf = Kf m Kf（H2O）=1.86 K·kg·mol-1 m= (989 92) ⁄ 1kg =10.75mol·kg-1 ΔTf =1.86 10.75=20(K) ΔTf =273- Tf溶液 Tf溶液=253K
(4） Osmotic pressure
10 （4）Osmotic pressure