CARBON, DIOXIDE OF THE-OCEAN 589 
Then, according to the law of mass action—— 
ke QO KS c 
where a and @ are the concentrations of the ions (Na and Cl) 
and ¢ of the dissociated salt." 
GO KS its 7 
Seo e 
This K is called the ionization or dissociation constant, and is 
a constant under constant temperatureand pressure, but is different 
tor each different salt. 
Salts, strong acids and bases (hydrochloric acid, sodic hydrate, 
etc.) are the substances most dissociated, while the weaker acids 
and bases (acetic acid, ferric or ammonium hydrate, ete: ) sare 
dissociated to a less degree, z. e., the constant K is smaller. 
It follows directly from equation (2) that the more diluted the 
solution the more complete is the dissociation. If the strength 
of the solution is such that concentration @ and 6 are each rep- 
resented by 2 andc by 4; and then the concentration of all be 
decreased so that a@ and 6 become 1, we find by substitution in 
the equation (2) that c also must become 1, and the ratio of 
dissociated to undissociated or molecular salt, is 1:1 instead 
Ofmtat 22 
Fleterogeneous equilibrium. We may have some undissolved 
substance (C) in contact with a saturated molecular solution (C, ) 
of the same substance which is dissociated, more or less, into its 
ions (Aand B). The concentrations are a and 6 for the ions, ¢c for 
the undissolved (solid) salt. and c, for the undissociated dis- 
solved part of C. Equilibrium being established between the 
solid C and the molecular solution of the solid (C2—C,), 
the equation is 
1: (3) 
But the concentration of a solid at given temperatures and pres- 
sures is a constant (its specific gravity) (¢ —K,), therefore 
* This simple formula is not strictly accurate in the case of electrolytic dissociation 
but is correct enough for our purpose. 
