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 iodide, NaI






The iodide is prepared by neutralizing sodium hydroxide or carbonate with hydriodic acid; or by the action of iodine on sodium hydroxide, and reduction with charcoal of the iodate simultaneously formed; or from sodium hydroxide and iodine in presence of iron-filings or ferrous iodide.

The dihydrate, NaI,2H2O, is a colourless, crystalline substance, readily soluble in water, and isomorphous with the corresponding hydrate of the chloride and with that of the bromide. The recorded values for the melting-point of the anhydrous salt vary between 603° C. (Ramsay and Eumorfopoulos) and 694.7° C. (MacCrae, who also gives 667.5° C.); Carnelley gives 630° C., Victor Meyer, Riddle, and Lamb 661.4° C., Huttner and Tammann 664° C., and Ruff and Plato 650° C. The melting-points of the halides of sodium and of the other alkali-metals fall as the atomic weight of the halogen increases. The boiling-point of sodium iodide is 1300° C., and the vapour-pressure in atmospheres corresponds with the expression

log p = - 37000/4.57T + 5.130.

For the density of the anhydrous salt Schroder gives the value 3.55, and Baxter and Brink 3.665 at 25° C.; for the dihydrate Surawicz gives 2.448. The specific heat between 26° and 50° C. is given by Schillier as 0.0881; and between 16° and 99° C. by Regnault as 0.0868. Thomsen gives the heat of formation from the elements as 69.08 Cal.; for the heat of solution of the anhydrous salt 1.2 Cal., and for the dihydrate -4.01 Cal.; for the heat of hydration of the anhydrous salt to the dihydrate he gives 5.23 Cal.

Solubility NaI
Solubility-curve of sodium Iodide.
The picture indicates the solubility of sodium iodide in water at various temperatures: The solubility-curve is in conformity with the existence of a pentahydrate, the transition-point to the dihydrate (D) being -13.5° C., that of the dihydrate to the anhydrous salt (E) being 65° C. The boiling-point of a saturated solution in contact with the solid is 141° C. At 25° C., 100 grams of ethyl alcohol dissolve 46.02 grams of sodium iodide. Sodium iodide dissolves in methyl alcohol, yielding at 15° to 16° C. needle-shaped crystals of the formula NaI,3CH3OH.

Other properties of aqueous solutions investigated are density, refractive index, molecular elevation of the boiling-point, vapour-pressure, specific heat, and electric conductivity. References are also appended to work on the compressibility, the solubility in organic solvents and sulphurous acid, the molecular weight in liquid sulphur dioxide, the electric conductivity in acetone and dilute alcohol, the non-existence of polyiodides, isomorphism with potassium iodide, and the formation of a double salt with silver iodide.


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