MH₃PO₄ = 3AH + AP + 4AO = 3×1+31+4×16 = 98g/mol
MCa(OH)₂ = ACa+2(AO+AH) = 40+2(16+1) = 74g/mol
In 98g H₃PO₄ se gasesc 4×16 = 64g O
74g Ca(OH)₂...............................32g O
x g Ca(OH)₂...............................64g O
x = 74×64/32 = Calculeaza !