1. Add excess BaCl2 in addition to sulfate ions:

BaCl2+Na2SO4=BaSO4↓+2NaCl

2. Add excess NaOH in addition to magnesium ions:

MgCl2+2NaOH=Mg(OH)2↓+2NaCl

3. Add excess Na2CO3 in addition to calcium ions and barium ions in BaCl2:

Na2CO3+CaCl2=CaCO3↓+2NaCl

4. Finally, add an appropriate amount of HCl to the filtrate to remove excess NaOH and Na2CO3:

HCl+NaOH=NaCl+H2O?

2HCl+Na2CO3=2NaCl+H2O+H2O. 2NaCl+H2O+CO2 gas

Expanded Information:

Crude salt contains silt The crude salt contains sediment and other insoluble impurities, as well as soluble impurities such as Ca 2 +, Mg 2 +, SO 4 2 - and so on. Insoluble impurities can be removed by filtration, while soluble impurities such as Ca 2+, Mg 2+, SO 4 2- can be removed by adding BaCl 2, NaOH and Na 2CO 3 solution to produce precipitation, or by adding BaCO 3 solid and NaOH solution. The water is then evaporated to obtain a purer refined salt.

Crude salt usually contains impurities such as calcium chloride, magnesium chloride and sodium sulfate. From an ionic point of view, the presence of impurity ions such as calcium ions, magnesium ions, sulfate ions, and then consider what they precipitate, and calcium ions usually become calcium carbonate. Precipitation, so that sodium carbonate, magnesium ions become magnesium hydroxide precipitation, adding sodium hydroxide, sulfate ions should become barium sulfate precipitation, adding barium chloride.

Then consider the order, in order to ensure complete removal of impurities, add excess reagents, sodium hydroxide does not interfere, can be placed anywhere, but the order of sodium carbonate and barium chloride is fixed, first add barium chloride and then sodium carbonate can ensure that the excess barium ions are removed through the formation of a barium carbonate precipitate, and on the contrary, excess cesium ions will be retained as a new impurity. Finally, the excess sodium carbonate and sodium hydroxide can be removed with hydrochloric acid.