64 AtfSWEXS TO PRACTICAL QUESTIONS 



HgO : O : : 10 : jr. 

 216 : 16:: 10: a:. 



16x10 



x = 216 =.74: + , grams. 



16. How much O can be obtained from 6 grains of 

 KCIO 3 ? 



KC1O 3 : O 3 : : 6 : x. 

 122.5 : 48 : : 6 : x. 



17. Hoiv much KCIO Z would be needed to produce 2 

 kilograms of O ? 



3 : KC10 3 : : 2 : x. 

 48 : 122.5 : : 2 : x. 



122.5x2 



x = - j^ - = 5.1 + , kilograms. 



18. How much KCl would be formed in preparing 1 

 kilogram of O ? 



Hence, O 3 : KCl : : 1 : x. 



48 : 74.5 : : 1 : x. 

 74 5 

 x = -j^- = 1.55 + , kilograms. 



19. Is it probable that all the elements fire discovered? 



No. But all new elements lately discovered have proved to 

 be chemical rarities. Probably all of the abundant and gener- 

 ally useful elements have been discovered. 



20. Is heat produced by oxidation ? 



It is a manifestation of chemical change. In this sense it 

 may be considered to be caused by it. 



21. What is the difference betiveen kinetic and potential 

 energy ? 



Kinetic energy is energy of motion ; potential energy is 

 that of position. (Consult Steele's Popular Physics, p. 35.) 



22. ^Vliy does running cause pantiny ? 



