As per the law of constant composition, a given sample will always contain the same number of elements that combine in the same mass proportion.
Therefore if a sample of 13.97 g of NaBr contains 22.39 % of Na by mass then, a sample of 5.75 g of NaBr would also contain 22.39% Na by mass
Hence:
Mass of Na = 5.75 g * 22.39/100 = 1.287 g
5.75 g of NaBr would contain 1.29 g of Na
1.287 grams of sodium, a 5.75 g sample of sodium bromide will contain.
The law of definite proportions is often known as Proust's law or the law of constant composition.
It holds that a chemical compound's component elements are always present in a fixed ratio (by mass) regardless of its source or method of creation.
By the law:
A sample of 13.97 g of NaBr contains 22.39 % of Na, then a sample of 5.75 g of NaBr would also contain 22.39% Na.
Hence,
[tex]\bold{Mass\; of\; Na = 5.75 g \times \dfrac{22.39}{100} = 1.287 g}[/tex]
Thus, 5.75 g sample of sodium bromide contains 1.287 g Na.
Learn more about Proust's law, here:
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