SCHLUNDT SPEED OF THE LIBERATION OF IODINE 27 



SECTION E. 



Acceleration of Speed by Other Acids. 



The presence of an excess of hydrochloric acid accelerates 

 the reaction. Will the presence of other acids have a sim- 

 ilar influence, and if so what is their comparative influence 

 on the speed of the reaction? Various acids, organic and in- 

 organic, were tested. 



Normal solutions of the following acids were prepared, 

 hydrobromic, nitric, sulphuric, boric, formic, acetic, pro- 

 pionic, butyric, tartaric, malic, lactic, succinic, and oxalic. 



A mixture containing equivalents of the components as 

 fifth normal solutions served as a basis throughout the in- 

 vestigations. The following is a general sample mixture 

 of 200 cc.- 



Normal Hydrochloric Acid 40.0 cc. 



Normal Potassium Iodide 40 . cc. 



Three times normal Potassium Chlorate 13.3 cc. 



Normal acid used as accelerator 20.0 cc. 



Water 86 . 7 cc. 



200.0 cc. 



It was found that none of the organic acids mentioned 

 increased the speed of the reaction. On the contrary they 

 all slightly retarded the liberation of iodine. [Boric acid 

 also shows a slight retardation of the speed.] This is 

 easily accounted for by the fact that some of the acids are 

 oxidized by potassium chlorate. It is also possible that 

 some of the halogens present go to form substitution 

 products of the acid. 



The results obtained by using hydrobromic, hydrochloric, 

 nitric, and sulphuric acids respectively as accelerators are 

 graphically represented in figure 6. Curve A represents 

 the speed when no accelerating acid is present. 



