Calculate the mass fraction of zinc in a 50 g sample of ZnS containing 3% impurities.
July 28, 2021 | education|
m (ZnS) = 50 g
w% (impurities) = 3%
w% (Zn) -?
1) Find the mass of pure zinc sulfide without impurities:
If the proportion of impurities is 3%, then the proportion of pure substance will be 97%
m (ZnS) = 50 g * 0.98 = 49 g.
2) Find the amount of zinc sulfide:
n (ZnS) = m: M = 49 g: 97 g / mol = 0.5 mol
3) Find the mass fraction of zinc in the composition of zinc sulfide according to the following formula:
w% (element) = (Ar (element) * n): Mr (substance) * 100%.
w% (Zn) = (65 * 0.5 mol): 97 * 100% = 32.5: 97 * 100% = 33.5%
Answer: w% (Zn) = 33.5%.
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