SOLUTION 111 



shaking the solute with the solvent for a sufficient length of time, 

 this maximum amount will finally be dissolved. The solvent is 

 then said to be saturated by the solute in question. Thus, 100 c.c. 

 of water at 18 will dissolve as much as 6.6 g. of potassium chlorate, 

 but not more. The same amount of water will dissolve 213.4 g. 

 of silver nitrate, however, before the solvent becomes satu- 

 rated. On the other hand, a saturated solution of chalk 

 (calcium carbonate) in water will contain only 0.0013 g. in 

 100 c.c. 



To describe these cases we should say that potassium chlorate 

 is only moderately soluble in water, silver nitrate very soluble, and 

 chalk insoluble. But no substance is absolutely insoluble. 



The number of grams of the solute required to saturate 100 c.c. 

 of the solvent we call the solubility of the substance (at the exist- 

 ing temperature). The solubilities at 18 of one hundred and 

 forty-two substances in water are given in a table printed inside 

 the cover, at the front of this book. A few additional examples 

 are given below (p. 113). 



In some cases there is no limit to the solubility, and therefore no 

 possibility of the solution reaching saturation. Thus alcohol or 

 glycerine and water will dissolve in one another in any proportion. 

 Such pairs of substances are said to be miscible in all proportions. 



Dilute and Concentrated Solutions. A dilute solution 

 is one containing little dissolved matter, whether the matter is 

 naturally very soluble or not. A concentrated solution is one 

 containing much of the dissolved substance, and such a solution 

 can be made with very soluble solutes only. 



Conditions affecting the Solubility of a Gas. When the 

 dissolving substance is a gas, led through, or confined above the 

 liquid at a definite pressure, the gas dissolves until a state of 

 equilibrium between dissolving and emission is reached, for 

 example, Oxygen (gas) ^ Oxygen (dissolved), and the liquid is 

 then saturated with the gas. 



