What is Sodium thiosulfate Na2S2O3 CAS 7772-98-7?
Sodium thiosulfate pentahydrate is an inorganic substance with the chemical formula of Na2S2O3·5H2O.
Sodium thiosulfate Na2S2O3 is a colorless monoclinic crystal, odorless, and has a cool and bitter taste. The specific gravity is 1.729, heated to 100 ℃, and five crystals of water are lost.
Soluble in water, insoluble in alcohol, with strong reducibility.
Sodium thiosulfate Na2S2O3 is easily weathered in dry air above 33 ℃ and deliquescent in humid air.
Sodium Thiosulfate Na2S2O3
| Items | Appearance | Na2S2O3•5H2O | Insolubles in water | Na2S | FeHeavy Metals (as Pb) | pH value (200g/L solution) | ||
| Standard | White crystallin | ≥99.0 |
|
≤0.001% | ≤0.001% | 6.5-9.5 | ||
Product characteristics of Sodium thiosulfate CAS 7772-98-7
1. Sodium thiosulfate pentahydrate has strong reducibility and can reduce chlorine and other substances.
2. Sodium thiosulfate has a strong complexation ability and can form a complex with silver bromide.
3. Sodium thiosulfate can be used as a sulfur supplement.
Sodium thiosulfate mainly has the following functions in concrete:
Water reducer: sodium thiosulfate can be used as a water reducer, which can reduce the water-cement ratio of concrete, reduce the evaporation rate of water, and thus reduce the shrinkage and cracking of concrete.
Early strength agent: sodium thiosulfate can promote the hydration reaction in concrete, and the hydration products can fill the pores in concrete and improve the density and strength of concrete.
At the same time, it can make mortar and concrete early strength, has a certain plasticizing effect on cement, and does not corrode steel bars.
According to the amount of concrete cementitious material, the amount of baking soda that needs to be added to one cubic meter of concrete is about 3% and 6%.
Inhibition of expansion: sodium thiosulfate reacts with hydrogen to form harmless sulfides, inhibiting concrete expansion.
Precautions of Sodium thiosulfate CAS 7772-98-7
1. This product is non-toxic and harmless, biodegradable, but not edible.
2. If it gets into the eyes, it should be rinsed with plenty of water in time.
3. If you cause allergies to part of the human body, you should consult a doctor in time.
FAQs of Sodium thiosulfate CAS 7772-98-7
Q: How is sodium thiosulfate prepared?
A: Sodium thiosulfate can be prepared in a number of ways, most commonly synthesized by heating a solution of sodium sulfite (Na₂SO₃) with sulfur (S). In this process, sodium sulfite and sulfur are mixed in water and reacted at the appropriate temperature to form sodium thiosulfate. Alternatively, it can be prepared by a reaction between sulfur dioxide (SO₂) and sodium sulfide (Na₂S). Whichever method is used, the final product needs to undergo the steps of filtration, concentration and crystallization to obtain pure sodium thiosulfate crystals.
Q: What are the applications of sodium thiosulfate in environmental science?
A: In environmental science, sodium thiosulfate is mainly used to treat chlorinated wastewater, especially from bleaching processes or disinfection processes. It can effectively convert free and bound chlorine into harmless chloride ions, thereby reducing the concentration of oxidizing substances in the water column and protecting aquatic ecosystems from damage. In addition, Sodium Thiosulfate can be used to detect iodine in water samples, as iodine reacts quantitatively when it meets Sodium Thiosulfate, a property that makes it an important reagent in titrimetric analyses. In soil remediation, sodium thiosulfate can be used to mitigate the effects of certain heavy metal contaminations, such as mercury contamination, because it forms insoluble mercury sulfide precipitates with mercury.
Q: What safety precautions should be taken when using sodium thiosulfate?
A: Although sodium thiosulfate itself is relatively stable and of low toxicity, there are a number of safety precautions that need to be taken during its use. Firstly, inhalation of its dust should be avoided as inhalation at high concentrations may irritate the respiratory tract and cause coughing or breathing difficulties. Secondly, care should be taken when in contact with the skin or eyes, as although it has a low irritant effect on the skin, prolonged exposure may result in dryness or mild irritation. If it accidentally gets into the eyes, you should immediately flush with plenty of water and seek medical help. Finally, storage should keep containers well sealed and away from strong acids and other corrosive chemicals to prevent unwanted chemical reactions. In laboratory or industrial environments, operators should wear appropriate personal protective equipment such as gloves, goggles and masks.
Q: What is the educational value of sodium thiosulfate in teaching chemistry laboratory?
A: Sodium thiosulfate has significant educational value in the teaching of chemistry experiments. It has been involved in many classic chemistry demonstration experiments, which not only show interesting chemical phenomena, but also help students understand the basic principles. For example, in the famous “iodine clock reaction” experiment, sodium thiosulfate reacts with iodine monomers to produce colorless iodide, and this process can be used as a timekeeping tool, allowing students to visualize the change in reaction rate. In addition, sodium thiosulfate is used to teach the concept of redox reactions because it can be used as both a reducing agent (oxidized by oxygen to sodium sulfate) and an oxidizing agent (reacts with sodium sulfite). By actually performing experiments containing sodium thiosulfate, students are able to better grasp points such as chemical equilibrium, acid-base neutralization, and complexation reactions. In conclusion, sodium thiosulfate is a very practical teaching tool that helps to stimulate students' interest in chemistry and deepen their understanding of related theories.
