Conductivity of Hypophosphoric Acid Solutions. 113 



water bath and continuing the heating in the same man- 

 ner for five or six hours. The residue was then carefully 

 diluted to the original volume. An iodometric analysis 

 by the method previously used, showed that the hydrol- 

 ysis of the hypophosphoric acid had been complete. The 

 conductivity of this solution was then measured in the 

 same way as before. 



Solution B was prepared from a sample of acid sodium 

 hypophosphate which had been recrystallized eight times. 

 This was converted into 'the copper salt by treatment 

 with pure copper sulphate, and the copper hypophos- 

 phate washed and finally decomposed with hydrogen 

 sulphide by the same method and with the same precau- 

 tions used in preparing Solution A. The use of the cop- 

 per salt has the advantage that the sulphate radical can 

 readily be tested for and its elimination insured. After 

 diluting the solution it was analyzed in the same manner 

 as Solution A. Duplicate samples gave 0-05499 and 

 0-05490 grm, of hypophosphoric acid per 20 cm 3 , and in 

 samples of the same volume 0-00015 and 0-00007 grm. of 

 phosphorous acid, thus showing the solution to be 0-03347 

 molar H 4 P 2 6 of which 99-80% was unhydrolyzed, a 

 higher degree of purity than that of Solution A. The 

 same conductivity measurements were then made with 

 Solution B, both before and after hydrolysis, as had 

 previously been made with Solution A. The results for 

 both solutions are recorded in Table IV. 







Table 



IV. 







Molecular Conductivity of Hypophosphoric Acid 



, H 4 P 2 O at 



25°. 





Solution A. 





Solution B. 





(98-: 



96% unhydrolyzed) 



(99-80% 



unhydrolyzed) 



Molee. 



f- 



H, after 



Molec. 



l« 



/j,, after 



concen- 



Molec. cond. 



complete 



concen- Molec. cond. 



complete 



tration 



Sol. A 



hydrolysis 



tration 



Sol. B 



hydrolysis 





ohm- 1 



ohm- 1 





ohm- 1 



ohm- 1 



003197 



381-2 



345-6 



003347 



3840 



3410 



001599 



415-4 



412-8 



0-01674 



416-2 



407-2 



0007993 



456-6 



483-8 



0008369 



4560 



4780 



0003997 



506-2 



5550 



0004184 



5050 



551-2 



0001998 



565-8 



614-6 



0002092 



564-8 



614-8 



00009992 



624-2 



666-2 



0001046 



626-4 



678-6 



To facilitate comparison with similar data recorded 

 in the literature we have recalculated our results to round 



Am. Jour. Sci. — Fourth Series, Vol. XLV. No. 266.— February, 1918. 



