1. Refining Sodium Chloride
Experiment 1
Refining Sodium Chloride

2. Purposes 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.

3. Principles
Crude salt usually contains soluble ions, such as Ca2+、 Mg2+、SO42- 、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, BaCl2, Na2CO3, HCl, etc.) to the solution of crude in which the precipitate can form.

4. Reactions

5. Procedure 1．Refining sodium chloride Weigh out 4g crude salt
15ml H2O
BaCl 2
Weigh out 4g
crude salt
dissolving △ △
Adding NaOH，Na2CO3
solution （evaporating dish）
K+、OH- 、CO32-
filtrating
concentrating
pH=4-6
NaCl crystal
HCl
drying

6. 2．Test the purity of the purified salt
test the SO42-
BaCl 2 solution
test the Ca2+ ion
(NH4)2C2O4
solution
test the Mg2+ ion
magnesium agent

7. Recording and handling data
1. Refining the sodium chloride
weight of crude salt m1 = g,
weight of purified salt m2 = g
yield of product (%）=

8. 2. Test the purity of the purified salt
Item
crude salt Solution
purified salt solution
Test the SO42－ ion
Phenomenon
Conclusion
Test the Ca2+ ion
Test the Mg2+ ion