1. To master the proper operations as well as the suitable situations of atmospheric pressure filtration, vacuum filtration, centrifugal separation & precipitation washing 2. To understand the relation between precipitation state % precipitating conditions 3. To learn the way to examine whether reactants are fully precipitated 4. To learn the principals of powder material synthesizing through room temperature solid phase method & liquid phase method directional growing
crystal form of precipitation
1.the process of precipitation forming
constitutive crystal ion
2. the classification of precipitations
amorphous precipitation, particle diameter smaller than 0.02 m, ex. Fe(OH)3. the hydroxide of metals of high oxidation number would grow directionally with low rate, but accumulate very fast, forming amorphous precipitation curd-like precipitation, particle diameter 0.02~0.1 m, ex.AgCl crystal form of precipitation, diameter 0.1~1 m, ex.BaSO4. Inorganic salts with strong polarizability grow directionally with high rate, forming crystal form of precipitation 3.CdS is a semiconductor material widely use. It can be preparated through room temperature solid phase method & liquid phase method & gas phase method. Use CdSO4 and NaS as reactants, through both room temperature solid phase method & liquid phase method to prepare CdS(s). Compare the two ways of preparation and their influence on product separation. Reactions as follows, CdSO4+2NaS=CdS+Na2SO4 Chemical reagents: CdSO4(s), Na2S(s), 0.3M HCL(aq), 0.5M CdSO4(aq), 1M BaCl2(aq), widely pH tests strips, mortar, centrifugal text tube, bake oven, centrifuge, vacuum filtration apparatus, etc. Experiment Steps And Phenomena
Room temperature solid phase method...