₁₆¹⁶S ₁₆¹⁷S ₁₆¹⁸S ₁₆²⁰S izotopii sulfului
M1=16+16; M2=16+17; M3=16+18; M4=16+20
M,mediu= c1M1+ c2M2+c3M3+ c4M4
=0,9502x32+0,0075x33+ 0,0421x34+ 0,0002x36=..............
M,S=32g/mol 1mol contine 6,023x10²³atomi (numarul lui Avogadro)
6,023x10²³at..........................32g
9,033x10²⁸..................................x............................calculeaza !!!!!