Insoluble impurities can be removed by filtration, while soluble impurities such as Ca2+, Mg2+ and SO42- can be removed by adding BaCl2, NaOH and Na2CO3 solution to generate precipitate, or adding BaCO3 solid and NaOH solution. Then the water is evaporated to obtain pure refined salt.
Drugs: crude salt, distilled water, BaCl? 2 solution, NaOH solution, Na? 2CO？ 3 solution, hydrochloric acid.
Equipment: tray balance (including weight), measuring cylinder, beaker, glass rod, medicine spoon, funnel, filter paper, iron shelf (with iron ring), evaporating dish, alcohol lamp, crucible pliers, rubber-tipped dropper, mortar, pestle, matches and several small pieces of paper.
Extended data:
Pay attention to one post, two lows and three inclines when filtering:
1, "one stick" means that the folding angle of the filter paper should be consistent with the diameter of the inner wall of the funnel, so that the wet filter paper can stick to the inner wall of the funnel without bubbles.
2. "Two lows" means that the edge of the filter paper is slightly lower than the edge of the funnel. During the whole filtration process, always pay attention to the fact that the filtrate level is lower than the edge of the filter paper.
3. "Three leaning" means that when the liquid to be filtered is poured into the funnel, the beaker mouth of the beaker containing the liquid to be filtered should lean against the inclined glass rod; The lower end of the glass rod should gently lean against the three-layer filter paper to prevent the filter paper from breaking; The neck of the funnel should be close to the inner wall of the receiver receiving filtrate to prevent liquid from overflowing.
Baidu encyclopedia-crude salt purification