A compound is found to consist of 34.5% sodium, 16.4% boron, and 48.6% oxygen. What is the empirical formula?
A. NaBO3
B. NaBO2
C. Na2B4O7
D. Na3BO3

Respuesta :

Answer: The empirical formula is [tex]NaBO_2[/tex]

Explanation:

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given:

Mass of Na= 34.5 g

Mass of B= 16.4 g

Mass of O = 48.6 g

Step 1 : convert given masses into moles.

Moles of Na =[tex]\frac{\text{ given mass of Na}}{\text{ molar mass of Na}}= \frac{34.5g}{23g/mole}=1.5moles[/tex]

Moles of B =[tex]\frac{\text{ given mass of B}}{\text{ molar mass of B}}= \frac{16.4g}{11g/mole}=1.5moles[/tex]

Moles of O =[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{48.6g}{16g/mole}=3moles[/tex]

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For Na = [tex]\frac{1.5}{1.5}=1[/tex]

For B = [tex]\frac{1.5}{1.5}=1[/tex]

For O =[tex]\frac{3}{1.5}=2[/tex]

The ratio of Na: B: O= 1: 1: 2

Hence the empirical formula is [tex]NaBO_2[/tex]

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