n1 moli Cr2O3 + 2Al = Al2O3 + 2Cr M Cr2O3 = 152g/mol
n2 moli 3MnO + 2Al = Al2O3 + 3Mn M MnO = 71g/mol
152n1 + 71n2 = 294
n1/n2 = 1/2 n2 = 2n1 152n1 + 142n1 = 294 n1 = 1molCr2O3 n2= 2 moli MnO
nAl = 2n1 + 2/3 n2 = 2+ 4/3 = 10/3 moli m = 10/3 x 27 = 90g