Red precipitation may be sodium polysulfide precipitation.Sodium sulfide is more likely to be oxidized by air to sodium polysulfide (make sulfur into single matter, and then produce sodium polysulfide). When the sulfur index of sodium polysulfide is high, it is dark red in the aqueous solution, and it emerges due to insoluble solution under anaqueous conditions.In addition, carbon tetrachloride may also decompose into sodium chloride (potassium) + sodium carbonate (potassium) and water (1:6 reaction can be written).The combination of oxidation and decomposition reactions may also promote each other, and other reactions may also occur.
Identification of the red-red precipitation reference method
Remove the red substance and wash it several times with absolute ethanol (try to wash the sodium sulfide solution) to see if it will dissolve.Add some carbon disulfide first to see if it solves (to check for sulfur alone, although it is yellow), and wash it several times with ethanol.Take a small amount of precipitation and dilute sulfuric acid, see if there is hydrogen sulfide escape (you should be able to smell out, you can also use wet lead acetate or lead nitrate test paper test), precipitation whether a large amount of conversion into light yellow or milky white turbidity, this is the product of sodium polysulfide (potassium) the phenomenon.The above experiments proved whether sodium polysulfide (potassium).It can also be designed to prove whether there is carbonate production (carbon tetrachloride alkali decomposition product).
Post time: Jun-13-2022
