16 VETERINARY STATE BOARD 



It is composed of two parts by weight of hydrogen and thirty-two 

 of oxygen. Formula H^O^. 

 Write the equation for the prjpparation of hydrogen dioxide. 



BaO^ + H,SO^ + H3O = BaSO, + H.O^ + H^O. 

 Mention the important properties and the uses of peroxide of hydrogen. 

 It is an active oxidizing agent and is used preeminently as a 

 disinfectant, bleaching agent, antisuppurant, and deodorant. 



Give the chemical explanation of the uses of hydrogen peroxide. 



It acts as an oxidizing agent because it is readily decomposed 

 into water, H^O, and nascent oxygen, 0. 



OXYGEN 



Describe oxygen as to (a) occurrence, (b) physical properties, (c) 

 chemical properties. 



(a) Most abundant of all the elements. Uneombined, but mixed 

 with nitrogen, it constitutes one-fifth of the atmosphere ; combined, 

 it forms eight-ninths of the material composing water, and nearly 

 half the weight of all the rocks. It is a very important constituent 

 of animal and vegetable matter. 



(b) A colorless, tasteless, odorless gas, nearly sixteen times 

 heavier than hydrogen, and somewhat heavier than air. It may be 

 made liquid or even solidified by great cold and pressure. 



(c) It supports combustion, but is non-combustible and is one 

 of the most powerful electronegative elements ; capable of uniting 

 with all elements except fluorine, bromine and the helium group. 



Describe a method of preparing oxygen. Give the symbol, atomic 



weight and specific gravity of oxygen. 



Mix potassium chlorate and manganese dioxide, equal parts, and 



apply heat, carefully; oxygen will be given off copiously. Symbol, 



0. Atomic weight, 16. Specific gravity, compared with hydrogen, 



is 16, compared with air, 1.1056. 



How much oxygen can be obtained from 50 grammes of potassium 

 chlorate? [Atomic weight of potassium = 39, of chlor- 

 ine = 35.5, of oxygen = 16.] 

 39 -j- 35.5 -f 48 = 122.5, the molecular weight of KCIO^. The 

 molecular weight of 3 atomis of oxygen = 48. 122.5 : 48 = 50 : X 

 X = 19.5 grammes. 



What is oxidation? Give an example. 



Oxidation is the union of oxygen with other elements, the prod- 

 ucts formed are oxides. Example: iron and oxygen unite to form 

 ferrous oxide. See reduction, p. 5. " 



