The purification yield of 2g crude salt is about 50% to 60%.

Crude salt purification is to extract the impurities contained in the salt to produce pure salt. Coarse salt contains insoluble impurities such as sediment, as well as soluble impurities such as Ca2+, Mg2+, SO42-?, etc.

Insoluble impurities can be removed by filtration. Ca2+, Mg2+, and SO42- in soluble impurities can be removed by adding BaCl2, NaOH and Na2CO3 solutions to form a precipitate. BaCO3 solids and NaOH solutions can also be added. to remove. The water is then evaporated to obtain purer refined salt.

Experimental phenomenon:

Dissolution: The solid of coarse salt is gray, and the liquid obtained after adding it to water is turbid.

Filtration: The filtrate is a colorless and transparent liquid, and the residue on the filter paper is black.

Evaporation: With heating, the amount of liquid in the evaporating dish decreases; when evaporation reaches a certain level, solids precipitate at the bottom of the evaporating dish, and the solid obtained by evaporation is white.

Reference for the above content: Baidu Encyclopedia - Coarse Salt Purification