Derive the chemical formula of a substance if it is known that the mass fraction of sodium in this substance

| August 28, 2021 | education

Derive the chemical formula of a substance if it is known that the mass fraction of sodium in this substance = 0.377 (37.7%), mass fraction of silicon = 0.23 (23%), mass fraction of oxygen = 0.393 (39.3%) Relative molecular mass = 122

The mass fraction of element X in the compound is calculated by the following formula:

w (X) = n * A (X) / Mr,

where n is the number of atoms of element X in the compound,

Mr is the relative molecular weight of the compound.

The relative molecular weight of the compound is known (122 amu), we find the atomic masses in the periodic table and then calculate the number n for each element.

n (Na) = w (Na) * Mr / A (Na) = 0.377 * 122/23 = 2

n (Si) = w (Si) * Mr / A (Si) = 0.23 * 122/28 = 1

n (O) = w (O) * Mr / A (O) = 0.393 * 122/16 = 3

The simplest formula of the compound: Na2SiO3 – sodium silicate.



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