Can anyone give a high school chemistry all the information on removing impurities

Starch [iodine], heated iodine sublimation.

Methane [ethylene], by the reaction of bromine water, ethylene and bromine water.

Acetic acid [ethyl ester], add a sufficient amount of sodium hydroxide solution to obtain sodium acetate and ethanol, distill, remove ethanol, and then add sufficient sulfuric acid, and then obtain a mixed solution of acetic acid and sodium sulfate, distilled to obtain acetic acid solution.

Ethylene [sulfur dioxide], soluble in water by water, carbon dioxide [gaseous hydrochloric acid], insoluble in sodium bicarbonate by sodium bicarbonate solution, CO2 insoluble in sodium bicarbonate.

Heat into an acidic KMno4 solution.

Separate funnels. Pass into NaOH solution.

Introduce a small amount of water.

Starch [iodine] Iodine turns blue when starch is encountered, and the two have reflected the ccl4 solution of methyl [ethylene] into bromine acetic acid [ethyl ester] first pass into the saturated Na2CO3 solution, separate the solution, remove the lower layer, and then add HCl

Ethylene [sulfur dioxide] is passed into the NaOH solution, carbon dioxide [gaseous hydrochloric acid] is passed into the saturated NaHCO3 solution.

Starch [iodine], heated iodine sublimation.

Methane [ethylene]: Introduced into bromine water or acidic potassium permanganate.

Acetic acid [ethyl ester]: add water, separate the liquid to remove the upper layer of ethyl ester, and distill to obtain pure vinyl acetate [sulfur dioxide]: pass into sodium hydroxide solution.

Carbon dioxide [gaseous hydrochloric acid]: passed into saturated sodium bicarbonate.

First of all, there are a few points that must be paid attention to in addition to miscellaneous.

1. No new impurities can be introduced.

2. You can't give away what you want (you can have more, for example, in addition to NaHCO3 in Na2CO3, you can't price HCl, so there are no two).

3. When removing impurities, the things added are excessive!! (This must be noted so that it is easy to introduce new impurities).

4. Feasibility, convenience. The melting and boiling point of any two substances is not the same, in principle, distillation or similar distillation methods can be used, but some are not easy to achieve, such as Fe mixed with Cu, the melting and boiling points of the two metals are very high, and the melting requires a very high temperature, not to mention boiling, so the distillation method is not feasible.

These are the two main points, and sometimes you have to consider the issues of pollution-free and cheap (most of which do not need to be considered).

Then there is the impurity removal method, which is divided into physical method and chemical method, and the physical method does not use chemical reaction, such as: in addition to the Fe in Cu, you can use magnet ......, ethanol in water is distilled.

The vast majority of the questions are still chemical.

It is necessary to pay attention to the above methods, mainly to grasp the impurities to be removed and the properties of the substances to be retained.

Also take Na2CO3 and NaHCO3 as examples, NaHCO3 is unstable and decomposes by heating, while Na2CO3 does not decompose when heated, you can consider using the method of heating, and then see if there are new impurities introduced, if not, this method can be used.

For example, in addition to Na2CO3 in NaCl, you can't use BaCl2, because when removing impurities, you use too much, so you can introduce a new impurity BaCl2, so you should pay special attention. HCL should be used to remove impurities, HCL is volatile, and there is no more after heating and evaporation.

The most important thing is to understand the properties of matter, because this kind of problem is very lively, and only mastering the properties of each substance is king!

The common removal of impurities in high school is to remove impurities in seawater