AIR AND OXYGEN 



31 



The change, together with the weights of the materials, is as 

 follows : 

 Potassium chlorate (122.56) -> Potassium chloride (74.56) + Oxygen (48) 



Potassium (39.1) 

 Chlorine (35.46) 

 Oxygen (48) 



Potassium (39.1) 

 Chlorine (35.46) 



A peculiarity of this action is that admixture of manganese 

 dioxide (the mineral pyrolusite) increases very markedly the 

 speed with which the decomposition of the potassium chlorate 

 takes place. Hence powdered manganese dioxide is generally 

 mixed with the chlorate in laboratory experiments (Fig. 18), and 

 in its presence a sufficient stream of oxygen 

 is obtained at a relatively low temperature 

 (below 200). 



4. Oxygen can be obtained conveniently 

 from sodium peroxide and water by means 

 of generators (Fig. 19) similar to the acety- 

 lene generators used on automobiles. When 

 the metal sodium is burned in air, sodium 

 peroxide is obtained as a powder. This 

 powder, after being melted, solidifies in 

 compact, solid form, and is sold as oxone. 

 The oxone is bought in a small, sealed tin 

 can, the ends of which are perforated in 

 several places just before use. When the 

 valve (B) is opened, so that the oxygen 

 escapes, the water, which fills the generator 

 almost to the top, enters the can (C) by the holes in the bottom 

 and interacts with the oxone. When the valve is shut, the gas 

 continues to be generated until it has driven the water down 

 again below the level of the bottom of the can. 

 Sodium peroxide (78) + Water (18) - Sodium hydroxide (80; -r Oxygen (16) 



Sodium (46) Hydrogen (2.016) Sodium (46) 



Oxygen (32) Oxygen (16) Oxygen (32) 



Hydrogen (2.016) 



This method is convenient because it works at room temperature 



\ 



FIG. 19 



