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课程名称：物理化学 - 表面化学 课程概述：本课程主要探讨吸附现象，即固体表面对物质分子的吸引和保留，导致表面浓度高于内部浓度。吸附的物质称为吸附质，而吸附发生的物质称为吸附剂。根据吸附方式的不同，吸附可分为物理吸附和化学吸附，前者由弱的范德华力维持，后者则由强的化学键结合。几乎所有固体都能吸附气体，气体在固体上的吸附程度受到气体性质、固体性质、固体表面积、气体压力和温度等多方面的影响。在恒温条件下，吸附程度（x/m）与气体压力之间的关系称为吸附等温线。 催化剂是一种能在反应中提高化学反应速率但自身不被消耗的物质，催化现象称为催化。在均相催化中，催化剂与反应物处于相同相态；而在非均相催化中，催化剂与反应物处于不同相态。 胶体溶液介于真溶液和悬浮液之间，胶体颗粒的大小范围为1到1000纳米。胶体体系由分散相和分散介质两部分组成，依据（i）分散相和分散介质的物理状态、（ii）分散相与分散介质间的相互作用以及（iii）分散相的颗粒性质，可将胶体体系分为三种类型。胶体体系显示出有趣的光学、机械和电学性质。将胶体颗粒通过添加适当的电解质转变为不溶性沉淀的过程称为凝聚。 乳液是分散相和分散介质均为液体的胶体体系，分为油在水型和水在油型。乳液的制备过程称为乳化。为了稳定乳液，通常添加乳化剂。肥皂和洗涤剂常被用作乳化剂。胶体在工业和日常生活中有着广泛的应用。
SUMMARYAdsorption is the phenomenon of attracting and retaining the molecules of a substance on the surface of a solid resulting into a higher concentration on the surface than in the bulk. The substance adsorbed is known as adsorbate and the substance on which adsorption takes place is called adsorbent. In physisorption, adsorbate is held to the adsorbent by weak van der Waals forces, and in chemisorption, adsorbate is held to the adsorbent by strong chemical bond. Almost all solids adsorb gases. The extent of adsorption of a gas on a solid depends upon nature of gas, nature of solid, surface area of the solid, pressure of gas and temperature of gas. The relationship between the extent of adsorption (x/m) and pressure of the gas at constant temperature is known as adsorption isotherm.A catalyst is a substance which enhances the rate of a chemical reaction without itself getting used up in the reaction. The phenomenon using catalyst is known as catalysis. In homogeneous catalysis, the catalyst is in the same phase as are the reactants, and in heterogeneous catalysis the catalyst is in a different phase from that of the reactants.Colloidal solutions are intermediate between true solutions and suspensions. The size of the colloidal particles range from 1 to 1000 nm. A colloidal system consists of two phases - the dispersed phase and the dispersion medium. Colloidal systems are classified in three ways depending upon (i) physical states of the dispersed phase and dispersion medium (ii) nature of interaction between the dispersed phase and dispersion medium and (iii) nature of particles of dispersed phase. The colloidal systems show interesting optical, mechanical and electrical properties. The process of changing the colloidal particles in a sol into the insoluble precipitate by addition of some suitable electrolytes is known as coagulation. Emulsions are colloidal systems in which both dispersed phase and dispersion medium are liquids. These can be of: (i) oil in water type and (ii) water in oil type. The process of making emulsion is known as emulsification. To stabilise an emulsion, an emulsifying agent or emulsifier is added. Soaps and detergents are most frequently used as emulsifiers. Colloids find several applications in industry as well as in daily life.
