A,Al= 27g/mol
M,AlCl3=( 27gAl+ 3x35,5gCl)/mol= 133,5 g/mol
2mol....................2mol
2Al + 3Cl2---> 2AlCl3 sau,in grame
2x27g................2x133,5g
x.................................120
x= 120x27/133,5=..........................gAl ..calculeaza !!!!