初中化学实验英文论文

I had already heard that potassium permanganate is a strong oxidant. In our daily life, we utilize it to disinfect cuts. Concentrated sulfuric acid, known by most people as a dangerous agent, was actually mysterious to me because I had had no access to it before. In this chemistry class, they were mixed and applied to a alchohol lamp. A fierce reaction happened. After a flash, the alchohol lamp was lit. It was so amazing to lit something without fire. Next experiment was about concentrated sulfuric acid. When pured into a cup filled with sugar, the sulfuric acid immediately turned the white sugar into black. Then, the black matter expanded dramaticly, accompanied by flame and smoke. I was so curious to figure out the principles behind the phenomena. I felt so excited about this class.

一、溶胶是怎样的概念胶体从外观上看貌似均匀，与溶液没什么差异，因此胶体常称为溶胶。溶胶与胶体是同一个概念。二、对淀粉、蛋白质等高分子溶于水形成的分散系，为什么有时称其为溶液，有时又称其为胶体教材中是按分散质微粒直径的大小来给分散系分类的。淀粉、蛋白质等高分子溶于水形成的分散系可称为胶体。但是判断一种分散系是属于胶体还是溶液，单从分散质微粒直径的大小这一方面来考察，其结论是不全面的，甚至是错误的。正确判断一种分散系是溶液还是胶体，还要看分散质微粒的结构。如果分散质微粒的结构简单，比如是单个的分子或较小聚合度的分子或离子，那么这样的分散系应称为溶液。由于淀粉、蛋白质溶于水后都是以单个分子的形式分散在水中的，因此，尽管这些高分子很大，这些分散系仍应称为溶液。只是因为高分子的大小与胶粒相仿，高分子溶液才具有胶体的一些特性，如扩散慢、不通过半透膜、有丁达尔现象等。化学上常把Fe（OH）3，AgI等难溶于水的物质形成的胶体称为憎液胶体，简称溶胶；而把淀粉、蛋白质等易溶于水的物质形成的分散系称为亲液胶体，更多地是称为高分子溶液。三、溶液是均一的，胶体也均一吗憎液溶胶的分散质微粒是由很大数目的分子构成，因此是不均一的；高分子溶液中的分散质微粒是单个的分子，因此是均一的。四、胶体能在较长时间内稳定存在的原因是什么憎液溶胶的胶粒带有相同的电荷，由于同性电荷的排斥作用而使憎液胶体可以稳定存在。淀粉、蛋白质等高分子中含有多个极性基团（如—COOH，—OH，—NH2等），可以与水高度溶剂化（高分子表面形成水膜），因此也可较长时间稳定存在。很明显，这两类胶体稳定存在的原因是不同的。五、溶液中的溶质微粒也作布朗运动吗胶体微粒在各个方向上都受到分散剂分子的撞击，由于这些作用力不同，所以胶体微粒作布朗运动。溶液中的溶质微粒和分散剂分子大小相仿，因此溶质微粒的运动状况与胶体的胶粒运动状况是有差别的。由于胶体的丁达尔现象，用超显微镜才可以观察到胶粒的布朗运动。溶液无丁达尔现象，因此用超显微镜观察不到溶质微粒的运动状况。六、凝聚与盐析有何差别凝聚是憎液（水）胶体的性质，胶体的凝聚过程就是胶粒聚集成较大颗粒的过程。由于憎液（水）胶体的分散质都难溶于水，因此，再采用一般的溶解方法用水来溶解胶体的凝聚物是不可能的，也就是说，胶体的凝聚是不可逆的。盐析实际上就是加入电解质使分散质溶解度减小而使其析出的过程。盐析不是憎液胶体的性质，它是高分子溶液或普通溶液的性质，能发生盐析的分散质都是易溶的，如淀粉溶液、蛋白七、蔗糖溶于水形成的分散系是溶液，为什么在生物课的渗透实验中，蔗糖分子却不能通过半透膜不同的半透膜，如羊皮纸、动物膀胱膜、玻璃纸等，其细孔的直径是不同的，也就是说，不同的半透膜，其通透性是不一样的。显然，笼统地讲半透膜能使离子或分子通过，而不能使胶体微粒通过是不恰当的。八、憎液胶体与高分子溶液在性质上有何异同憎液胶体全面地表现出胶体的特性，高分子溶液则不然。这两种分散系中的分散质微粒都作布朗运动，都有丁达尔现象；憎液胶体有电泳现象，淀粉溶液无电泳现象，而蛋白质溶液则较为复杂；使憎液胶体凝聚的方法有：加入电解质、给胶体加热、加入带相反电荷的胶体，使高分子溶液中的分散质沉淀，主要是破坏高子分与分散剂间的相互作用，如加入大量的电解质也能使淀粉、蛋白质沉淀，这一现象称为盐析，它是可逆的。九、有没有溶液能产生类似于胶体的电泳现象由于溶液是均一的，不存在“界面”，因此，给溶液通电不会产生界面移动现象（即一极液面高，另一极液面低），但是有些溶液通电后却可以产生一极溶液颜色加深，另一极溶液颜色变浅的现象。比如，给紫红色KMnO4溶液通电一段时间后，阳极附近溶液的颜色就会变深，阴极附近溶液的颜色就会变浅。这是由于通电后，紫红色的MnO4－向阳极移动，但却不会在阳极放电（MnO4－远比OH－难放电）的缘故。CuSO4溶液就不会产生类似的现象，因为Cu2＋会在阴极放电。十、Fe（OH）3胶体长时间电泳或电压增大，将发生怎样的现象如果Fe（OH）3胶体长时间电泳或将电泳的电压显著增大，都会在阴极出现凝聚现象，因为不论是长时间电泳还是电压显著增大，都会使阴极附近积聚很多的Fe（OH）3胶粒，大量胶粒的聚集必然会出现凝聚现象。如果电泳电压特别大，还会出现电解水的现象。质溶液、肥皂的甘油溶液，由于分散质都是易溶的，所以盐析是可逆的。First, what is the concept of sol Judging from the appearance of seemingly homogeneous gel, with no difference in the solution, so often referred to as sol-gel. Sol and gel is the same concept. 2, starch, protein and other water-soluble polymer dispersed system formed, why the solution is sometimes called, sometimes also called it as colloidal Quality of teaching is dispersed particle diameter according to the size of a decentralized system classification. Starch, protein and other polymer dissolved in water to form colloidal dispersion system can be called. But the determination of a colloidal dispersion system or solution are, just from the dispersed particle diameter size of the mass to examine this aspect, the conclusion is incomplete, even wrong. Correct determination of a solution or colloidal dispersion system is, depends on the structure of particle dispersion quality. If the quality of particle dispersion structure as simple as a single molecule or smaller degree of polymerization of the molecules or ions, then it should be called the solution of the decentralized system. As the starch, protein is dissolved in water to form a single molecule dispersed in water, so, even though these polymers large distributed systems should still be called the solution of these. Only because of the size of polymer particles similar, only with the gel polymer solution of some features, such as the proliferation of slow, not through the semipermeable membrane, with Tyndall phenomena. Chemistry often to Fe (OH) 3, AgI and other substances insoluble in water, the formation of colloidal liquid gel called monks, called sol; while the starch, protein and other substances soluble in water, the formation of liquid disperse system as pro- colloid, more is known as the polymer solution. Third, the solution is homogeneous, uniform gel also do Hate liquid sol particle dispersion quality by a large number of molecules, it is uneven one; polymer solution, the dispersion of particles is a single molecular mass, and therefore uniform. 4, colloid stability can exist over an extended period because of what Hate liquid sol particles with the same charge, due to charge repulsion Ershi homosexual hate colloidal solution can exist. Starch, protein and other polymers containing multiple polar groups (such as-COOH,-OH,-NH2, etc.), can be highly solvent and water (molecular water film formed on the surface), so there can be a long time stability . Obviously, these two types of colloidal stability of the reason there are different. 5, solution for Brownian motion of solute particles also do Colloidal particles in all directions are subject to the impact dispersant molecules, because these forces because of their different colloidal particles as Brownian motion. Solution of solute particles and dispersant molecules are similar in size, so the movement of solute particles and colloidal particles movement situation is different. As the colloidal Tyndall phenomenon, with a super microscope can observe particles of the Brownian motion. Solution without Tyndall phenomenon, not so ultra-microscope, the movement of the solute particles. 6, the difference between condensation and salt Cohesion is hate liquid (the water) colloidal nature of the condensation process of colloidal particles to larger particles that process. As the monks liquid (water) quality is immune colloidal dispersion of water-soluble, therefore, re-dissolution method commonly used in water to dissolve colloidal aggregates is impossible, that is, the concentration of colloid is not reversible. Electrolyte salt is actually added to its decentralized nature and the solubility decreased precipitation process. Liquid colloidal salt is not the nature of hate, it is common solution polymer solution or the nature of the dispersion of salt can occur are soluble nature, such as starch solution, protein VII, sugar dissolved in water to form the dispersion system is a solution Why infiltration in biology class experiment, but can not be semi-permeable membrane sucrose molecule Different semi-permeable membrane such as parchment, animal bladder film, cellophane, its pore diameter is different, that is, different semi-permeable membranes, the permeability is not the same. Obviously, generally speaking semi-permeable membrane allows ions or molecules to pass through, without giving colloidal particles through is not appropriate. 8 and hate liquid colloid and polymer solution of the similarities in the nature of Comprehensive demonstration of monks colloidal solution colloidal properties of polymer solution is not. This decentralized system of two particles in the dispersion quality are as Brownian motion, there Tyndall phenomenon; hate liquid gel with electrophoresis, starch solution without electrophoresis, the protein solution is more complicated; to hate liquid colloid aggregation methods are: adding electrolyte to gel heating, by adding gel with the opposite charge, so that the dispersion of polymer solution quality of precipitation, mainly sub-divided and the destruction of high interaction between dispersant, such as adding a large number of electrolyte also make starch, protein precipitation This phenomenon is known as salting, it is reversible. 9, there is no solution to produce phenomena similar to gel electrophoresis As the solution is homogeneous, there is no "interface", and therefore to the solution of power does not produce the phenomenon of interface movement (ie a very high surface, another extremely low liquid level), but after powering some of the solution but the solution can generate a very color deepened, and the other pole solution faded color phenomenon. For example, purple KMnO4 solution to power after a period of time, the color of the solution near the anode will become darker in color of the solution near the cathode will be lighter. This is because the power, the purple MnO4-move to the anode, but not in the anode discharge (MnO4-OH-hard than the discharge) of the reason. CuSO4 solution will not produce a similar phenomenon, because Cu2 + in the cathode discharge. 10, Fe (OH) 3 gel electrophoresis time or voltage increases, the phenomenon will happen to If Fe (OH) 3 gel electrophoresis or electrophoresis time the voltage was increased significantly and there will be condensation phenomena in the cathode, because whether or voltage electrophoresis time was significantly larger accumulation near the cathode will cause a lot of Fe (OH) 3 particles, the aggregation of a large number of particles bound to the phenomenon of condensation. Particularly if the electrophoresis voltage, electrolysis of water is still there. Quality solution, glycerin soap solution, due to dispersion quality are soluble, so salt is reversible.