Cas No.16721-80-5 NaSH 70% Solid Flake
Colorless needle-like crystals. Deliquescence. At the melting point, hydrogen sulfide is liberated. Easily soluble in water and alcohol. The aqueous solution is strongly alkaline. It reacts with acid to generate hydrogen sulfide. Bitter taste. Used in the dye industry to synthesize organic intermediates and to prepare auxiliaries for the preparation of sulfur dyes, in the leather industry for dehairing and tanning of hides, in the chemical fertilizer industry to remove monomer sulfur in activated carbon desulfurizers, and in the mining industry for copper ore. It is used for sulphurous acid dyeing in mineral processing and man-made fiber production. It is the raw material for the manufacture of semi-finished products of ammonium sulfide and pesticide ethyl mercaptan. It is also used for wastewater treatment. It is obtained by absorbing hydrogen sulfide gas from alkali sulfide or caustic soda solution.
| Sodium Hydrosulfide
|Acidic Sodium Sulfide
| sealed and dried
Chinese name: Sodium HydrosulfideChinese synonyms: acidic sodium sulfide; sodium hydrosulfide (70%); sodium hydrosulfide; sodium hydrosulfide (NAHS, XH2O); sodium hydrogen sulfide; sodium hydrogen sulfide anhydrous;English synonyms: hidrosulfurosodics; hydrogenosulfuredesodium(french);hydrogenosulfuredesodium,anhydre;hydrogenosulfuredesodium,dihydrate;hydrogensodiumsulfide;sodiumhydrogensulfide(nahs);sodiumhydrosulfide(na(hs));sodiumhydrosulfide,anhydrous;Mol file: 16721-80-5.mol;CAS NO: 16721-80-5;EINECS number: 240-778-0.
Appearance and properties: white to colorless cubic crystals with the smell of hydrogen sulfide; industrial products are generally in solution, orange or yellow.
Melting point (℃): 52.54
Relative density (water = 1): 1.79
Flash point (℃): 90
Solubility: soluble in water, soluble in ethanol, ether, etc.
It quickly decomposes into sodium hydroxide and sodium sulfide in moist air, emits heat and is easy to ignite spontaneously.
It turns yellow or orange when heated in dry air, and turns black when melted. It dissolves in HCl to produce H2S, and the reaction is intense. Easily deliquescence, strong hygroscopicity, easy to oxidize, hydrogen sulfide and sulfur are often released during storage.
Relevant reaction equation:
1. Absorption method:
Use alkali sulfide solution (or caustic soda solution) to absorb hydrogen sulfide gas. Because hydrogen sulfide gas is toxic, the absorption reaction should be carried out under negative pressure. In order to prevent excessive hydrogen sulfide in the exhaust gas from polluting the air, several absorbers are operated in series during production, and the hydrogen sulfide content is reduced to a lower level after repeated absorption. The absorption liquid is concentrated to obtain sodium hydrosulfide. Its chemical equation:
2. Sodium alkoxide reacts with dry hydrogen sulfide to produce sodium hydrosulfide:
In a 150 mL flask with a branch tube, add 20 mL of freshly distilled anhydrous ethanol and 2 g of sodium metal with a smooth surface and no oxide layer. The flask is equipped with a reflux condenser and a drying tube, and the branch tube is closed first. When the sodium alkoxide precipitates, add about 40 ml of absolute ethanol in batches until the sodium alkoxide is completely dissolved.
Insert a glass tube straight into the bottom of the solution through the branch pipe, and pass in dry hydrogen sulfide gas (note that no air can enter the flask from the sealed branch pipe). Allow the solution to reach saturation. The solution was suction filtered to remove the precipitate. Store the filtrate in a dry Erlenmeyer flask, add 50 mL absolute ether, and immediately a large amount of NaHS white precipitate precipitates. Leave it for a period of time, and then add ether several times until the upper layer solution no longer appears white precipitate. A total of about 110 mL of ether is needed. The precipitate was filtered out quickly, washed with absolute ether for 2 to 3 times, sucked dry, and placed in a vacuum desiccator. The purity of the product can reach analytical purity. For higher purity NaHS, it can be dissolved in ethanol and recrystallized with ether.
3. It is usually prepared by the method of absorbing hydrogen sulfide with sodium hydroxide solution. When the content (mass fraction of sodium hydrosulfide) is 70%, it is a dihydrate and is in the form of flakes; if the content is lower, it is a liquid product. Trihydrate.
4. Anhydrous sodium hydrosulfide:
A stirrer and a reflux condenser were installed on a 1-liter three-necked round-bottom flask, the mouth of the latter was connected to a calcium chloride drying tube, and the other neck of the flask was plugged.
First flush the flask with dry nitrogen. Add 200 ml (3.4 mol) of absolute ethanol, and then quickly add 12 g (0.522 mol) of clean metal sodium cut into small pieces, stir and reflux. After dissolving the sodium, use the neck of the flask to install a gas tube with the lower end extending into the liquid. The hydrogen sulfide dried by phosphorus pentoxide is passed into the stirred solution at a flow rate of 5-10 bubbles per second for 2 hours. After cooling, sodium hydrosulfide precipitates out. When the solution was cooled to room temperature, 750 ml of anhydrous ether was added to completely precipitate the sodium hydrosulfide.
Complete the following operations as quickly as possible to prevent the flood of sodium hydride from absorbing water. The reaction solution was filtered with a coarse-pore glass core funnel and washed three times with anhydrous ether. The ether was evaporated, and the product was quickly placed in a vacuum dryer containing calcium chloride to dry for several hours, and 29.4 grams of product with a purity of 98% or more was obtained.
5. Sodium hydrosulfide aqueous solution:
Dissolve sodium sulfide nonahydrate in freshly steamed filling water, and then dilute it into a 13% Na2S (W/V) solution. Add 14 g of sodium bicarbonate to the above solution (100 ml) under stirring and below 20°C, which immediately dissolved and exothermed. Then, 100 ml of methanol was added while stirring and below 20°C. At this time, heat was released again, and almost all crystalline sodium carbonate was precipitated immediately. After 0 minutes, the mixture was filtered with suction, and the residue was washed with methanol (50 ml) several times. The filtrate contained not less than 9 g of sodium hydrosulfide and not more than 0.6 of sodium carbonate. The concentrations of the two are about 3.5 grams and 0.2 grams per 100 milliliters of solution, respectively.