Calculate the mass fraction of oxygen (percent) in the H3PO4 substance.
| June 10, 2021 | education
Formula for calculating the mass fraction of an element in a substance:
w = n * Ar (chemical element) / Mr (substance), where n is the number of atoms of a given chemical element.
1) Find the relative molecular weight of the substance (H3PO4):
Mr (H3PO4) = 3 * Ar (H) + Ar (P) + 4 * Ar (O) = 3 + 31 + 64 = 98
2) Find the mass fraction of a given element (O) in the substance:
w (O) = 4 * 16/98 = 0.65 or 65%
Answer: Mass fraction of oxygen in phosphoric acid is 65%.
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