Preparation of sodium thiosulfate
53 grams of the sodium carbonate are dissolved in 300 ml of hot water and about five-sixths of the solution is placed in one flask and the remainder in another flask. Those flasks are connected in series so that sulfur dioxide gas may be passed first into the larger volume of solution, and what is there unabsorbed may pass on through the second flask. A stream of sulfur dioxide is passed vigorously into the solutions of sodium carbonate. After a short time, a marked frothing occurs in the first flask, due to the escape of carbon dioxide, and after this frothing ceases a similar frothing soon commences in the second flask. When the latter ceases, sulfur dioxide is passed a little while longer until the gas escapes freely from the second bottle. The obtained solution of sodium bisulfite is placed in a 600 ml beaker and cautiously treated with 53 grams of sodium carbonate. The solution is boiled for 15 minutes then is treated with 48 grams of powdered sulfur wetted with small amount of ethanol and gently boiled under reflux for an hour and a half or longer. The obtained solution is filtered and the residual sulfur is rinsed with 15 ml of water (the residual amount of sulfur could be dried and weighed in order to find whether the calculated quantity has reacted). The filtrate is evaporated to a volume of 200 ml and cooled to 30° C and if any unchanged sodium sulfite is left it will separate as a crystal meal which is to be filtered off. The solution is left at room temperature in a crystallizing dish until an abundant crop of crystals is obtained. Sodium thiosulfate can remain in highly supersaturated solution; it is best, therefore, to add some seed crystals to the solution set to crystallize. Sodium thiosulfate obtained by described method contains five molecules of water – Na2S2O3 · 5H2O.
Synthetic inorganic chemistry, by A. A. Blanchard, 252-254, 1936
SODIUM THIOSULFATE, Sodium thiosulphate, 7772-98-7, Hypo, Disodium thiosulfate, Sodium thiosulfate anhydrous, sodiumthiosulfate, Chlorine Cure, Chlorine Control, Declor-It, Sodium thiosulfate (Na2S2O3), Sodium thiosulphate (Na2S2O3), Hypo (VAN), Sodium oxide sulfide (Na2S2O3), Sodium thiosulfate solution, UNII-L0IYT1O31N, Sodium thiosulfate, anhydrous, HSDB 592, Thiosulfuric acid, disodium salt, EINECS 231-867-5, NSC 45624, AI3-01237, Thiosulfuric acid (H2S2O3), disodium salt, Hypo alcohol, sodium thio-sulfate, Hyposulphite of soda, ACMC-1BLMJ, AC1L2NGO, AC1Q1USN, Na2S2O3, Sodium thiosulfate,anhydrous, L0IYT1O31N, HT1005_SIGMA, Sodium thiosulfate concentrate, KSC377E1T, Thiosulfuric acid (H2S2O3), sodium salt (1:2), HT1005_SIAL, 319546_ALDRICH, 34449_RIEDEL, 35224_RIEDEL, 35233_RIEDEL, 35244_RIEDEL, 38200_RIEDEL, 38243_RIEDEL, 563188_ALDRICH, 34449_FLUKA, 35224_FLUKA, 35233_FLUKA, 35244_FLUKA, 38200_FLUKA, 38243_FLUKA, 72049_FLUKA, 85192_FLUKA, 85192_SIGMA, CTK2H7219, 10102-17-7 (pentahydrate), 319546_FLUKA, AKHNMLFCWUSKQB-UHFFFAOYSA-L, MolPort-003-926-155, MolPort-006-118-733, 72049_SIAL, 217263_SIAL, AKOS015856704, AKOS016372312, RP22166, RTR-031296, TRA0058020, BP-21059, SC-74795, Thiosulfuric acid (H2S2O3) disodium salt, LS-153406, TR-031296, LT03329071, X5843, I14-16584, 13773-27-8, 220945-47-1
Sodothiol, Sodium hyposulfite, S-Hydril, Thiosulfuric acid disodium salt, disodium dioxido-oxo-sulfanylidene-, CID24477, STS