1. cred ca vrei sa spui masa de sulfura de aluminiu ... si NU de zinc
M.Al2S3 = 2x27+3x32 = 150 g/mol
2,7 moli m g
2Al + 3S --> Al2S3
2 150
=> m = 2,7x150/2 = 202,5 g Al2S3
2.
M.CaCl2 = 40+2x35,5 = 111 g/mol
20 moli n moli
Ca + Cl2 --> CaCl2
1 1
=> n = 20x1/1 = 20 moli CaCl2
nr.moli = m/M.CaCl2 => m = 20x111 = 2220 g CaCl2
3.
M.MgO = 24+16 = 40 g/mol
48g m g
2Mg + O2 --> 2MgO
2x24 2x40
=> m = 48x2x40/2x24 = 80g MgO