Chemical elements
  Sodium
    Isotopes
    Energy
    Preparation
    Applications
    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
      Sodamide
      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 sulphate, Na2SO4






The sulphate is often called "Glauber's salt," on account of its application in the seventeenth century as a medicine by the physician Glauber, the specific being known as "sal mirabile Glauberi." Its purgative action seems to be a phenomenon dependent on osmosis.

The anhydrous sulphate is a constituent of oceanic salt deposits, and is called thenardite. An isomorphous mixture with potassium sulphate is known as glaserite; a double salt with magnesium sulphate as astrakanite, and with calcium sulphate as glauberite.

Sodium sulphate is an intermediate product in the manufacture of sodium carbonate by the Le Blanc process. It is also a byproduct in the manufacture of nitric acid by the interaction of sodium nitrate and sulphuric acid:

2NaNO3+H2SO4=Na2SO4+2HNO3.

In the Stassfurt deposits sodium chloride and magnesium sulphate monohydrate or kieserite are present, and on cooling the solution to -3° C. sodium sulphate crystallizes out. A mixture of sodium chloride, magnesium sulphate, and sand also reacts at dull red heat to form sodium sulphate and magnesium silicate, with evolution of chlorine. In Hargreaves's process sodium chloride reacts with a mixture of sulphur dioxide, steam, and air, producing sodium sulphate and hydrochloric acid. Sodium sulphate is also produced by treating the calcium sulphide of the alkali-waste with sodium hydrogen sulphate formed in the manufacture of nitric acid:

2NaHSO4+CaS=Na2SO4+CaSO4+H2S.

Sodium sulphate is a white, tetramorphous substance, crystallizing below 200° C. in the rhombic or monoclinic system, from 200° to 500° C. in another rhombic form, and above 500° C. in the hexagonal system. It forms a heptahydrate and decahydrate. For the melting-point of the anhydrous salt Ruff and Plato give 880° C.; Wolters, 881° C.; McCrae, 881.5° and 885.2° C.; Arndt and Naeken, 883° C.; Heycock and Neville, 883.2° C.; Ramsay and Eumorfopoulos, van Klooster, and Dana and Foote, 884° C.; Bocke, 888° C.; and Huttner and Tammann, 897° C. Nacken observed neither decomposition nor volatilization at the melting-point. The transition-point of the monoclinic into the second rhombic form is given by Nacken as 234° C., by Huttner and Tammann as 235° C., and by Boeke as 239° C. The density of the anhydrous solid is given by Retgers as 2.673 at 15° C., by Krickmeyer as 2.671 at 20° C.; for that of the fused salt from the melting-point to 1000° C., Brunner gives the interpolation-formula

dt =2.065-0.00045(t - 900°);

and for the decahydrate Clarke gives 1.465, Andreae 1.4665, and Rosicky 1.49.

For the temperature range 28° to 57° C. Schuller found for the specific heat 0.2293, and for 17° to 98° C. Regnault found 0.2312. For the heat of formation from the elements Thomsen gives 328.6 Cal., and Berthelot 328.1 Cal. Thomsen's value for the heat of neutralization is 31.38 Cal., and for the heat of solution of the anhydrous sulphate he found 0.46 Cal. For the heat of solution of the decahydrate Thomsen gives -18.8 Cal., and Berthelot -18.l Cal. The heat of hydration of the anhydrous salt to the decahydrate is given by Thomsen as 19.22 Cal., and by Berthelot as 18.64 Cal.

The solubility of the anhydrous salt diminishes with rise of temperature from 33° to 120° C., as indicated in the table of solubility.

Sodium sulphate forms double salts with potassium sulphate and magnesium sulphate.


Solubility of Sodium Sulphate

Solid Phase, Na2SO4,10H2O



Temperature, °C.010203032.75
Grams Na2SO4 in 100 grams water5.09.019.440.850.65


Solid Phase, Na2SO4,7H2O



Temperature, °C0510152025
Grams Na2SO4 in 100 grams water19.52430374453


Solid Phase, Na2SO4



Temperature, °C333540506080100120140160230
Grams Na2SO4 in 100 grams water50.650.248.846.745.343.742.541.954244.2546.4


Solubility Na2SO4
Solubility-curve of sodium sulphate
Lowel gives the transition-point of the heptahydrate into the anhydrous salt (E) as 24.4° C., and that of the decahydrate into the anhydrous salt (F) is given by Richards and Wells as 32.383° C., and by Dickinson and Mueller as 32.384° C. The solubility relations are graphically represented in fig.

A saturated solution of sodium sulphate containing 42.2 grams of sulphate per 100 grams of water boils at 101.9° C. at 751 mm. Pressure, or 108.668° C. at 760 mm. pressure.

Sodium sulphate readily forms a supersaturated solution in water. When a solution is cooled to about 5° C., the heptahydrate crystallizes out. The crystals of the decahydrate weather in air, owing to loss of water of crystallization.

Reduction of sodium sulphate with charcoal at red heat produces sodium sulphide and carbon monoxide, along with sodium polysulphides and carbon dioxide. Addition of alcohol to a solution of sodium sulphate in aqueous hydrogen peroxide precipitates a complex derivative of the formula Na2SO4,9H2O,H2O2.
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