1)La acest tip de probleme se foloseste nr lui Avogadro 6,023 * 10 la 23 molecule
Intr-un mol de substanta se afla 6,023 9* 10 la 23 molecule
nr moli CO2 = masa CO2/masa molara CO2 = 880/44 = 20 moli
1 mol CO2........6,023 * 10 la 23 molecule
20 moli CO2............x molecule
x = 12,046 * 10 la 24 molecule!!!
2)Fosfatul de calciu are formula Ca3(PO4)2
%X = masa X/masa din care face parte X * 100 - formula procentuala in general
masa Ca3(PO4)2 = 3 * 40 + 2*(31+4*16) = 120+2*95=310 g
%Ca = 3*40/310 * 100 = 38,71%
%P = 2*31/310 * 100 = 20%
%O = 8*16/310 * 100 = 41,29 %
