Table 1, Effect of precipitate formed by the addition of Q*S cc. M, 

 NaOH to 200 cc, 0.5 M. FeSO, on pH aftei- aging 20 hours at room tempera- 



ture. 



pH 



Solution 



FeSO[j with precipitate in suspension 5,5 



FeSOj, after most of precipitate was removed li.5 3.U 



Precipitate in vmber suspension 6,1 5.1 



Table 2. pH change vfith time for a solution containing 100 cc. 0.5 M, 

 FeSOr and 7.5 cc. 1 I'l. HaOH. Column 2 shov/s result when air is bubbled 

 through solution, and Column 3 shovfs when solution is protected from 

 air by a stream of nitrogen. Each was agitated and readings were taken 

 quickly to minimize instrument drift. 



Time pH 



hrs:min 



0:03 



0:15 



0:30 



0:Ji5 



1:00 



1:15 

 1:30 



l:i;5 



2:20 



2:50 

 20:00 

 30»00 



K - 11 



