pt inceput calculezi masele moleculare:
MCa3(PO4)2=3ACa+2AP+8A0=3·40+2·31+8·16=310 g in care gasim 120 g CA
Mca(oh)2=74g in care gasim 40 g Ca
DAca in 74 g Ca(OH)2 .......................40 g Ca
Atunci in x g Ca(OH)2............................120g Ca
x=(120·74):40=222 g Ca(OH)2
daca ai intrebari, intreaba :)