CHANGE IN VELOCITY OF REACTION 125 



of nitrogen is stronger than that of oxygen, and the latter 

 than that of chlorine. But there are also influences that 

 cannot be brought under this heading but point rather to 

 spatial relations. 



i. Acceleration of Reaction that precedes Separation 

 of Ions. 



(a) Influence of Oxygen. 



In organic compounds oxygen causes in general an 

 increase in velocity of reaction, and tends particularly to 

 overcome the inertia of carbon combination referred to on 

 p. 97. This principle is confirmed in various directions, and 

 only the most important cases need be brought forward 

 here. 



Gradually accelerated Oxidation. A striking fact, and 

 one observed in cases outside the carbon compounds as well, 

 is the successively increased facility with which oxygen 

 replaces hydrogen when once partial oxidation has set in. 



Amongst organic compounds this gradual facilitation of 

 oxidation is seen most simply in the oxygen derivatives 

 of methane, 



CH 4 , H 3 COH, H 2 CO, H 2 C0 2 , CO 2 , 



which are successively easier to oxidize, a fact all the 

 more striking since the reverse is true of the chlorine 

 derivatives, 



CH 4 , CH 3 C1, CH 2 C1 2 , CHC1 3 , CC1 4 . 

 Methane is oxidized w r ith difficulty, as is well known, for 

 not even chromic acid in presence of sulphuric acid does 

 so, although this mixture attacks methyl alcohol ; methyl- 

 ene oxide (formaldehyde) oxidizes in air, causing activation 

 of oxygen, and an antiseptic action ; it, moreover, reduces 

 silver oxide ; finally, formic acid goes a step further in this 

 direction, and will even reduce mercuric oxide. On the 

 other hand, methane is easily chlorinated, methyl chloride 

 less so, and chloroform least. 



