Page:Outlines of Physical Chemistry - 1899.djvu/234

 216 OUTLINES OF PHYSICAL CHEMISTEY

In face of these difficulties I have endeavoured to find whether the hypothesis of free ions is absolutely necessary, and whether another sort of dissociation would not suffice to explain the observed facts. Let us assume for the moment that sodium chloride reacts with water in the following manner :

NaCl + HOH = NaOH + HC1.

The number of active particles is doubled just as it is according to Arrhdnius's hypothesis, and consequently the abnormal values found for the osmotic pressure and the correlative data are equally well explained.

But a difficulty presents itself in the fact that it is not only the salt which behaves as an electrolyte ; hydro- chloric acid and caustic soda possess the same character, and for the factor i give a value which is almost equal to 2.

In consequence, I propose to bring forward again an

old idea, and assume that in a free acid the hydrogen

plays the part of a metal and in a free base the hydroxyl

is a true acid radical. In this manner the molecules + - + -

H CI and Na OH have the constitution of salts, and as

such they dissociate under the influence of solvent-water :

H CI + HOH = H OH + H CI

Basic water

Na OH + HOH = Na OH + H OH

Acidic water

Comparing these two equations with that which we supposed for the dissociation of sodium chloride :

Na CI + HOH = Na OH + H CI

we notice a perfect analogy.

We may further recognise that if in its ordinary state

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