192 SMITH'S INTERMEDIATE CHEMISTRY 



The Properties of Bases. The properties of bases (p. 167) 

 are properties of hydroxyl ion OH~. A base is a substance which 

 contains hydroxyl as a negative radical and, in solution, gives 

 hydroxyl ion. 



Many substances, such as ethyl alcohol C 2 H 5 OH, contain the 

 hydroxyl group, but their solutions exhibit none of the charac- 

 teristic properties of a base. They are not bases, since they do 

 not contain hydroxyl as an ionizing radical. 



A strong base is one which is highly ionized in solution, and 

 therefore shows the properties of hydroxyl ion very markedly. 

 It will be observed that the most active bases (alkalies) are the 

 hydroxides of those metals (K, Na, Ba) which come first on the 

 activity list (p. 54). Weak bases, like ammonium hydroxide and 

 copper hydroxide, are little ionized in solution, and exhibit the 

 properties of hydroxyl ion only feebly. Water is an exceedingly 

 weak base. 



The Properties of Salts. Salts are substances which contain 

 a positive ionizing radical other than hydrogen, combined with 

 a negative ionizing radical, other than hydroxyl. The properties 

 of a salt in solution are the properties of its two ions (see p. 175). 



Some salts do indeed contain hydrogen or hydroxyl as a radical, 

 but always in addition to two other radicals. Thus sodium-hydro- 

 gen sulphate (p. 126) gives H+ in solution, as well as Na + and 

 S0 4 = . This is an add salt. The precipitate actually obtained 

 by the action of a soluble carbonate on a cupric salt (p. 179) 

 has the composition Cu 2 (OH) 2 C0 3 . It is a basic salt. 



Neutralization. This is a special case of double decom- 

 position between electrolytes in solution, the reacting substances 

 being an acid and a base. The products of the reaction are a 

 salt and water. Thus the mixture of equivalent amounts of 

 hydrochloric acid and sodium hydroxide solutions gives a reaction 

 which is compkte, although no substance concerned in the reaction 



