Răspuns:
Al2S3
M=(2X27gAl + 3x32gS)/mol= 150g/mol=150mg/mmol
150mgAl2S3..........54mgAl
x....................................45
x=m= 125mgAL2S3
sau
mAl/mS= 54/96 mAl+mS= M,Al2S3
IN (54+96 ) mgAl2S3...........54mgAl
x...................................................45mg
Explicație: