Chemical elements
    Physical Properties
    Chemical Properties
      Sodium hydride
      Sodium fluoride
      Sodium hydrogen fluoride
      Sodium chloride
      Sodium bromide
      Sodium iodide
      Sodium hypochlorite
      Sodium chlorate
      Sodium hypobromite
      Sodium bromate
      Sodium hypoiodite
      Sodium iodate
      Sodium periodates
      Sodium monoxide
      Sodium peroxide
      Sodium hydroxide
      Sodium perhydroxide
      Sodium monosulphide
      Sodium polysulphides
      Sodium hydrogen sulphide
      Sodium sulphite
      Sodium hydrogen sulphite
      Sodium potassium sulphite
      Sodium pyrosulphite
      Sodium sulphate
      Sodium hydrogen sulphate
      Sodium monopersulphate
      Sodium pyrosulphate
      Sodium persulphate
      Sodium thiosulphate
      Sodium dithionate
      Sodium trithionate
      Sodium tetrathionate
      Sodium pentathionate
      Sodium hyposulphite
      Sodium selenides
      Sodium selenite
      Sodium selenate
      Sodium sulphodiselenide
      Sodium tellurides
      Sodium tellurate
      Sodium nitride
      Sodium hydrazoate
      Sodium hydrazide
      Sodium hyponitrite
      Sodium nitrite
      Disodium nitrite
      Sodium nitrate
      Sodium phosphides
      Sodium dihydrophosphide
      Sodium hypophosphite
      Sodium phosphites
      Sodium dihydrogen phosphite
      Sodium hypophosphates
      Sodium orthophosphates
      Disodium hydrogen orthophosphate
      Sodium pyrophosphate
      Disodium dihydrogen pyrophosphate
      Sodium metaphosphate
      Sodium polyphosphate
      Sodium arsenites
      Sodium arsenates
      Sodium antimonate
      Sodium carbide
      Sodium carbonate
      Sodium hydrogen carbonate
      Sodium percarbonate
      Sodium cyanide
      Sodium thiocyanate
      Sodium silicates
      Sodium borates
    PDB 131d-1bli
    PDB 1bph-1d10
    PDB 1d11-1ej2
    PDB 1eja-1gb5
    PDB 1gb6-1goh
    PDB 1gq2-1ikp
    PDB 1ikq-1jz1
    PDB 1jz2-1kvs
    PDB 1kvt-1me8
    PDB 1mg2-1nsz
    PDB 1nta-1oyt
    PDB 1p0s-1qjs
    PDB 1qnj-1s5d
    PDB 1s5e-1tjp
    PDB 1tk6-1uxt
    PDB 1uxu-1vzq
    PDB 1w15-1xc6
    PDB 1xcu-1yf1
    PDB 1ygg-1zko
    PDB 1zkp-2afh
    PDB 2agv-2bhc
    PDB 2bhp-2cc6
    PDB 2cc7-2dec
    PDB 2deg-2ein
    PDB 2eit-2fjb
    PDB 2fld-2gg8
    PDB 2gg9-2h9j
    PDB 2h9k-2ien
    PDB 2ieo-2jih
    PDB 2jin-2omd
    PDB 2omg-2p77
    PDB 2p78-2q68
    PDB 2q69-2qz7
    PDB 2qzi-2v35
    PDB 2v3h-2vwo
    PDB 2vx4-2wig
    PDB 2wij-2x1z
    PDB 2x20-2xmk
    PDB 2xmm-2zfq
    PDB 2zfr-3a6s
    PDB 3a6t-3b1e
    PDB 3b2n-3bos
    PDB 3bov-3ccr
    PDB 3ccs-3d7r
    PDB 3d97-3e3y
    PDB 3e40-3erp
    PDB 3euw-3fgw
    PDB 3fh4-3g3r
    PDB 3g3s-3gxw
    PDB 3gyz-3hwt
    PDB 3hww-3ijp
    PDB 3imm-3k0g
    PDB 3k13-3l7x
    PDB 3l88-3max
    PDB 3mbb-3mr1
    PDB 3mty-3nu3
    PDB 3nu4-3ot1
    PDB 3ow2-3qwc
    PDB 3qx5-3tfr
    PDB 3tfs-3v6o
    PDB 3v72-4ag2
    PDB 4aga-4eae
    PDB 4ecn-4g8t
    PDB 4gdt-8icw
    PDB 8icx-9icy

Sodium hyposulphite, Na2S2O4

The Sodium hyposulphite was first prepared in solution by Schutzenberger by reducing a solution of sodium hydrogen sulphite with zinc, but the yield is unsatisfactory. Bernthsen and Bazlen obtained the pure substance by reducing the primary sulphite with zinc-dust in presence of sulphurous acid,

2NaHSO3 + SO2 + Zn = Na2S2O4 + ZnSO3 + H2O,

precipitating the zinc and removing the excess of acid by addition of milk of lime, the hyposulphite being salted out in the form of dihydrate by addition of sodium chloride. They recommend increasing the stability of the dihydrate by washing with acetone, at first dilute and finally pure, and drying in a vacuum. Jellinek advises heating the dihydrate at 60° C. in vacuum, the process transforming it into the stable anhydrous salt. The hyposulphite can also be produced under special experimental conditions by the electrolytic reduction of sodium hydrogen sulphite, Jellinek having obtained a 7 to 8 per cent, solution by this means. Prepared by this process, it finds application in the reduction of indigo to indigo-white.

The anhydrous hyposulphite is also formed by the interaction of sulphur dioxide and sodium hydride:


The anhydrous salt is converted into the dihydrate by crystallization from water.

A laboratory method for the preparation of sodium hyposulphite depends on the interaction of sodium formaldehydesulphoxylate, NaCH3O3S,2H2O, and sodium hydrogen sulphite, the product having a purity of 80 to 85 per cent., and the yield being 55 to 60 per cent, of that theoretically possible. The sodium formaldehydesulphoxylate can be obtained by the reduction of commercial "hydrosulphite " by zinc-dust and zinc oxide in presence of formaldehyde solution, the crude product being recrystallized from water at 70° C.

Sodium hyposulphite dihydrate forms colourless vitreous prisms, readily soluble in water. On heating it loses its water of crystallization, melts at red heat, and burns with a blue flame, evolving sulphur dioxide. On addition of acid in small proportion the solution develops a red colour, due to separation of sulphur. Molecular-weight determinations by the cryoscopic method indicate it to be the salt of a dibasic acid, and to be represented by the formula Na2S2O4.

At temperatures between 0° and 30° C. the salt decomposes in aqueous solution in accordance with the scheme

Na2S2O5+H2O =2NaHSO3.

Hydrogen sulphide has no action on dry sodium hyposulphite, but in presence of water it reacts as indicated by the equation


The sulphur is obtained in a weighable form, and Sinnatt advocates the estimation of sodium hyposulphite by this method.

The method devised by Seyewetz and Bloch for the valuation of this substance depends on the oxidizing action of an ammoniacal solution of silver chloride:

Na2S2O4+2AgCl+4NH4OH =2(NH4)2SO3+2NaCl+2H2O + 2Ag.

Hollingsworth Smith has improved the speed of the operation, and has also eliminated the defect due to solid impurities in the hyposulphite being weighed with the silver.

Sodium hyposulphite is oxidized by iodine to sodium hydrogen sulphate, a reaction applied by Bazlen and Bernthsen to the quantitative estimation of the salt:

Na2S2O4+6I+4H2O =2NaHSO4+6HI.

The action of selenium and tellurium on sodium hyposulphite has been investigated by Tschugaev and Chlopin.

The hyposulphite was employed by Julius Meyer in the preparation of metallic colloidal solutions. It finds technical application as a reducer in the dye-industry. When administered intravenously, it exerts a toxic effect.

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