MANGANESE AND CHROMIUM 535 



Exercises. 1. Give a list of the classes of manganese com- 

 pounds and, in each class, the formulae of several compounds, the 

 prevailing color, and the valence of manganese in that class. 



2. Make equations for the formation of: (a) manganous sul- 

 phate; (b) manganous carbonate (insol.); (c) sodium manganate; 

 (d) the oxidation of hydrochloric acid by potassium permanganate. 



3. What action did we find to be catalyzed by manganese 

 dioxide? 



