masa atomica molara a Ca este 40g/mol , nu 80 !!!!!!!
se stie ca 1 mol atomi contine N,A=6,023X10²³atomi(numarul lui Avogadro)
deci 40g..............N,A atomi
x...........................1 atom
x=m= 6,64x10⁻²³ g
40g............N,A atomi
80g.............x= 2N,A=2x6,023x10²³at= 12,046x10²³ at.
