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Question
Solve the following problem:
Work out the percentage composition of constituent elements in the following compound:
Lead phosphate [Pb3(PO4)2]
(At. mass: Pb = 207; P = 31; O = 16; K = 39; Cr = 52; Na = 23; N = 14)
Solution
Given: Atomic mass: Pb = 207; P = 31; O = 16; K = 39; Cr = 52; Na = 23; N = 14
To find: The percentage composition of constituent element
Formula: Percentage (by weight) =
Calculation: Lead phosphate [Pb3(PO4)2]
Molar mass of Pb3(PO4)2 = 3 × (207) + 2 × (31) + 8 × (16)
= 621 + 62 + 128
= 811 g mol−1
Percentage of Pb =
Percentage of P =
Percentage of O =
Mass percentage of Pb, P, and O in lead phosphate [Pb3(PO4)2] are 76.57%, 7.64%, and 15.78% respectively.
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