Reshetnyak A. V., Shevchenko L. V., Posudiievska O. R.
Oles Honchar Dnipropetrovsk National University
GENERAL PROPERTIES OF SODIUM THIOSULFATE
Sodium thiosulfate is widely used in household activities as well as in industry. The investigation of its use of the method of its production in the industry and of its physicochemical properties is actual nowadays. Therefore, it became the task of our research work.
There exist many ways to get sodium thiosulfate which are based on different processes. The processes, having production value, are mainly the following:
– sulfite method;
– hydrosulfide method;
– sulfide method;
– hydrosulfite method;
– disulfide method.
Moreover, sodium thiosulfate is obtained as a byproduct in the production of hydrosulfite and during purification of industrial gases from sulfur. It can also be prepared by the sulfate method, using Na2SO4. Among the methods that have lost commercial value, we should mention the action of sulfur dioxide and oxygen (air) mixture on the solution of sodium sulfide and the oxidation of calcium sulfide (dump at soda production) with atmospheric oxygen, followed by calcium thiosulfate double replacement with sodium sulfate.
For the accomplishment of the procedure of preparation of sodium thiosulfate we did the following:
– dissolved in a small Erlenmeyer flask 2 g. of sodium sulfite in 25 ml. water;
– grinded in a porcelain mortar 2 g. of sulfur (better to use sublimed sulfur), moisten with alcohol and transfer to a flask with the solution of sodium sulfite;
– heated the mixture to its boiling point. The sing of end of the reaction solution according to the universal indicator paper;
– added 2 g. of sodium sulfite two more times with continuing boiling until a neutral reaction is observed in each case;
– drained the obtained hot solution though the paper filter on the funnel for hot filtration and evaporated it on the water bath to one third of the original volume. Filtrated the cooled precipitated crystals on the Buchner funnel.
For the determination of properties of sodium thiosulfate we:
– dissolved a few crystals of sodium thiosulfate in a small amount of water and added 2 ml. of hydrochloric acid;
– placed in small pot a few crystals of sodium thiosulfate and hearted them carefully at first, then to a large extent;
– poured 4 ml. of chlorine water and added the solution of sodium thiosulfate in drops until the disappearance of chlorine smell;
– carried out the same experiments with bromine and iodine water.
Asset of experiments was separately performed research the interaction of sodium thiosulfate with soluble salts of copper, zinc, lead, iron.
According to the results of the work we can draw the following conclusions:
1. We considered and investigated physical and chemical properties of sodium thiosulfate and thiosulfate acid.
2. The main methods of obtaining sodium thiosulfate in industry were considered. As the most promising method for obtaining sodium thiosulfate we can offer sulfide method of its preparation, since it does not require the usage of quite expensive starting materials.
3. Sodium thiosulfate is widely used as an antidote in medicine, as a fixer in photo production, as well as in textile and light industry.
Sodium thiosulfate exhibits complex properties that used to extract silver from silver ores and waste dumps. Sodium thiosulfate creates rather stable complexes with mane heavy metals. The research of the properties of this complexes can be used to develop new methods and ways of extracting metals from poor ores and refuse dumps.