Calculate the relative molecular weight of substances and the mass fractions of elements in them: Na2O, SnO2, BaSO3.

| February 8, 2021 | education

Let’s write down given: Na2O, SnO2, BaSO3
Find: Mr (Na2O) – ?, Mr (SnO2) – ?, Mr (BaSO3) -?, W (Na) – ?, w (O) -?, W (Sn) -?, W (O) -? , w (Ba) -?, w (S) -?, w (O) -?
Decision:
Let’s calculate the relative molecular weight of the Na2O substance and the mass fractions of sodium and oxygen in this compound.
Mr (Na2O) = 23 * 2 + 16 = 62
w (Na) = 23 * 2/62 = 0.74 or 74%
w (O) = 16/62 = 0.26 or 26%
Let’s calculate the relative molecular weight of the SnO2 substance and the mass fractions of tin and oxygen in this compound.
Mr (SnO2) = 119 + 16 * 2 = 151
w (Sn) = 119/151 = 0.79 or 79%
w (O) = 16 * 2/151 = 0.21 or 21%
Let’s calculate the relative molecular weight of the BaSO3 substance and the mass fractions of barium, carbon and oxygen in the given substance.
Mr (BaSO3) = 137 + 32 + 16 * 3 = 217
w (Ba) = 137/217 = 0.63 or 63%
w (S) = 32/217 = 0.15 or 15%
w (O) = 16 * 3/217 = 0.22 or 22%
Answer: Mr (Na2O) = 62 w (Na) = 0.74 or 74% w (O) = 0.26 or 26%; Mr (SnO2) = 151 w (Sn) = 0.79 or 79% w (O) = 0.21 or 21%; Mr (BaSO3) = 217 w (Ba) = 0.63 or 63% w (S) = 0.15 or 15% w (O) = 0.22 or 22%



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