ACTION OF CONCENTKATED SULPHURIC ACID ON IRON. 59 



PRODUCTS OF the ACTION of CONCENTRATED 



SULPHURIC ACID on IRON. 



By C. W. R. Powell, 



Science Research Scholar, University of Sydney, 

 (Communicated by Professor C. E. Fawsitt, d.Sc, Ph.D.) 



[Read before the Royal Society of N. S. Wales, June 4, 1913.~\ 



The action of sulphuric acid on metals generally seems to 

 depend largely on the temperature at which the reaction 

 takes place and upon the concentration of the acid. The 

 reactions generally accepted are : — 



(1) that dilute sulphuric acid, either hot or cold, acting 



on a metal produces hydrogen gas and sulphate of 

 the metal according to the equation : — 



M + H 2 S0 4 = MS0 4 + H 2 , 

 where M is any divalent metal, and — 



(2) that concentrated sulphuric acid in the cold has 



very little action, but when heated produces sul- 

 phur dioxide gas, sulphate of the metal and water: — 

 M + 2H 2 S0 4 = MS0 4 + S0 2 + 2H 2 0. 



Statements in connection with the action of concentrated 

 sulphuric acid on metals in the cold are somewhat conflict- 

 ing, but it would appear that the nature of the reaction, if 

 any takes place, is very largely influenced by the metal 

 employed. Baskerville 1 groups the reactions with copper 

 into two classes. 



(A) Primary. 



1. Cu + 2H 2 S0 4 = CuS0 4 + S0 2 + 2H 2 0, 

 this reaction taking place in two stages: — 



(a) Cu + H 2 S0 4 = CuSO, + 2H; 



(b) 2H + H 2 S0 4 = S0 2 + 2H 2 0. 



2. 5Cu + 4H 2 S0 4 = Cu 2 S + 3CuS0 4 + 4H 2 0. 



1 Jour. Amer. Chem. Soc. xvn, p. 904, (1895). 



