1.
nr atomi= n (nr moli) x NA (nr lui Avogadro=6.022 x10^23 particle/mol)
10 x 6.022 x 10^23=...
2.
FeCl3 + 3 NaOH = Fe(OH)3 + 3 NaCl
v sol.= 600 cm cubi =0.6 l
n NaOH= 1 x 0.6 =0.6 mol NaOH => m=0.6 x 40 g/mol=24 g
3 mol NaOH .... 1 mol Fe(OH)3
0.6 mol NaOH..... x mol Fe(OH)3
x= 0.6/3 = 0.2 mol Fe(OH)3
m Fe(OH)3= 0.2 mol x 106.9 g/mol =21.38 g Fe(OH)3