Calculate the mass fraction of Zn in Zn (NO3) 2.
| June 15, 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 (Zn (NO3) 2):
Mr (Zn (NO3) 2) = Ar (Zn) + 2 * Ar (N) + 6 * Ar (O) = 65 + 28 + 96 = 189
2) Find the mass fraction of a given element in the substance:
w (Zn) = 65/189 = 0.34 or 34%
Answer: Mass fraction of zinc in Zn (NO3) 2 34%.
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