Experiment 1 Refining Sodium Chloride 1 To master

Experiment 1 Refining Sodium Chloride

1. To master the usage of glassware washing， alcohol burner and platform balance. 2. Practice the basic operation of dissolving, filtrating, evaporating, concentrating and drying. 3. To learn the general theories and methods of refining sodium chloride.

• Crude salt usually contains soluble ions, such as Ca 2+、 Mg 2+、SO 42 - 、K+ and other insoluble impurities. The insoluble material can be removed by filtrating the solution of crude salt and the soluble ones can be eliminated by adding the proper reagents (for example, Ba. Cl 2, Na 2 CO 3, HCl, etc. ) to the solution of crude in which the precipitate can form.

Reactions

1．Refining sodium chloride Weigh out 4 g crude salt 15 ml H 2 O △ Adding Na. OH，Na 2 CO 3 filtrating concentrating Na. Cl crystal drying dissolving Ba. Cl 2 △ solution （evaporating dish） dish K+、OH- 、CO 32 - p. H=4 -6 HCl

2．Test the purity of the purified salt test the SO 42 Ba. Cl 2 solution test the Ca 2+ ion test the Mg 2+ ion (NH 4)2 C 2 O 4 solution magnesium agent

Recording and handling data 1. Refining the sodium chloride weight of crude salt m 1 = weight of purified salt m 2 = yield of product (%）= g, g

2. Test the purity of the purified salt Item Test the SO 42－ ion Test the Ca 2+ ion Test the Mg 2+ ion crude salt Solution purified salt solution Phenomenon Conclusion Phenomenon Conclusion