Sagot :

Bonjour:

1) M= 9 x 12 + 8 x 1 + 4 x 16 =  180 g.mol

2) n=m/M =500E-3/180 =2,77E-3 mol

3) N= n x Na = 2,77E-3 x  6,022E23 = 1,67E21