Removal of impurities is a chemical term, which refers to the physical or chemical method used to remove other substances in the target substance, so that it can be transformed into the main pure substance.
basic principle
(1) Try not to introduce new ones impurity 。 (2) The experimental procedure is the least.
(3) Remove impurities as much as possible.
(4) It is better to transform impurities into main pure substances.
(5) Reduce the loss of target materials. For example, remove sodium bicarbonate In sodium carbonate , is to take the aqueous solution of sodium bicarbonate and inject sufficient carbon dioxide , the reaction formula is as follows: Na2CO3+H2O+CO2===2NaHCO3
Another example is to remove sodium bicarbonate from sodium carbonate. Because sodium bicarbonate is easier to decompose than sodium carbonate, and sodium carbonate is difficult to decompose as follows:
2NaHCO3====(heating) Na2CO3+CO2+H2O
If these five principles are met, impurities can be eliminated.
