Abstract The principle of removing soluble impurities in crude salt is a key point in teaching, and the experimental steps are the most important. Traditionally, most teachers thought the sequence for the addition of sodium hydroxide and barium chloride couldn’t affect the result of the experiment. However, according to the calculation, it is found that the sequence will largely affect the removal of sulfate ion because of the salt effect. Therefore, sulfate ion should be removed first in the procedure of this experiment.
CAO Kui, LI Yan, YANG Xiao-Ling. Sulfate Ion Must be Removed in the First Step to Remove Soluble Impurities in Crude Salt: Analysis From Salt Effect Perspective[J]. Chinese Journal of Chemical Education, 2021, 42(7): 104-107.
