What is the empirical formula for a compound that is comprised of 54.0% sodium, 8.50% boron, and 37.5% oxygen by mass? A) Na2B2O3.
B) Na3BO3.
C) Na3B2O2.
D) Na4BO4.

B) Na3BO3.

Explanation:

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In this case, since percent compositions are used to identify the empirical formula of an unknown compound, we can assume we have 54.0 g of sodium, 8.50 g of boron and 37.5 g of oxygen, and we compute the moles of each one:

Now, we divide by the moles of boron as those are the fewest:

Thus, the empirical formula is B) Na3BO3.

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