348 OXYGENATED COMPOUNDS OF CHLOKINE. 



It follows from these numbers that combustion effected ly 

 solid potassium chlorate liberates more heat than the same com- 

 bustion effected by means of free oxygen; viz. by + T83 Cal. 

 for each equivalent of oxygen (0 = 8) consumed (p. 134). 



9. The formation of chlorates from the elements 



K + Cl + 3 = KC10 3 (solid) liberates + 94'6 Cal. 

 Na + Cl + 3 = NaC10 3 (solid) liberates + 85'4 Cal. 



These quantities scarcely vary with the temperature ; at least 

 when the metals are solid. In fact, the specific heat of the 

 system of elements, K + Cl + 3 , is 21*3 ; heat of the compound 

 KC10 3 is 23-8. We have then U - V = - 2-5 cal. (T - t) t 

 or, what is the same thing, - 0'0025 Cal. (T - t) y if we adopt 

 the same unit as for the formation of chlorates. An interval of 

 100, then, only produces an increase of - 0'25 Cal. in the heat 

 liberated. 



10. Various reactions. The action of gaseous chlorine on 

 diluted potash may be considered as forming either hypo- 

 chlorite, or chlorate, or free oxygen. 



(a) With hypochlorite 



6C1 + 3K 2 (diluted) = 3KC10 (dissolved) + 3KC1 (diluted). 



According to the experiments performed, 1 the reaction liberates 



+ 25-4 x 3 = + 76-2. 



With soda, we have, + 75'9 ; with baryta, + 75'8. 



(b) This reaction may also form chlorate 



6C1 + 3K 2 (diluted) = KC10 3 (dissolved) + 5KC1 (dilute), 



which liberates, with potash, + 94'2 ; with soda, + 94'2 ; with 

 baryta, + 95'0. 



(c) The formation of potassium perchlorate and chloride, 

 referred to the same weight of chlorine as the preceding 



|[8C1 + 4K 2 (diluted) = 7KC1 (dissolved) + KC10 4 

 (dissolved)], liberates + 11 TO. 



With soda, + 111-0 ; with baryta, -f 111-8. 



(d) Finally, the same reaction may develop chloride and free 

 oxygen p 



6C1 + 3K 2 (diluted) = 6KC1 (dissolved) + 3 , 



which liberates, with potash, + 111-0; with soda, + 110*0; with 

 baryta, + 111'8. 



It follows from these numbers that the formation of the 

 hypochlorite corresponds to the least liberation of heat ; then 

 comes the chlorate, and finally the perchlorate and free oxygen, 

 which liberate the most heat, the two quantities being, moreover, 



1 " Annales de Chimie et de Physique," 5 e seVie, torn. v. pp. 335, 337, 338. 



