Question

Calculate the mass percent composition of each constituent element of lead (II) phosphate

Pb =

P =

O =

Answer 1

Molar mass of Pb3(PO4)2,

MM = 3*MM(Pb) + 2*MM(P) + 8*MM(O)

= 3*207.2 + 2*30.97 + 8*16.0

= 811.54 g/mol

MM = 811.54

Lets calculate the mass of each element

mass of Pb = 3*MM(Pb)

= 621.6 g

mass of P = 2*MM(P)

= 61.94 g

mass of O = 8*MM(O)

= 128 g

mass % = (mass of element *100)/molar mass of compound

Now calculate mass percent of each element

Mass % of Pb = (621.6*100)/811.54

= 76.6

Mass % of P = (61.94*100)/811.54

= 7.6

Mass % of O = (128*100)/811.54

= 15.8

Answer:

Pb : 76.6 %

P : 7.6 %

O : 15.8 %