Ordinarily, we would perform the calculation........:
#"Concentration"="Moles of solute"/"Volume of solution"#;
and thus #"moles of solute"="volume"xx"concentation"#; and
#"mass of solute"="volume"xx"concentration"xx"molar mass"#
#=5.6*Lxx2.1*mol*L^-1xx86.94*g*mol^-1~=1000*g#.
The problem is that #MnO_2# is as soluble as a brick, and you would not be able to achieve these concentrations.......This insolubility lent itself to an important (preindustrial) applications, i.e. as a pigment in oil painting. Umber (from Umbria in Italy where the ore was mined) featured in the great paintings of Rembrandt and Caravaggio as a deep orange-brown.
