A compound analyzes to be 37.5% C, 12.5% H, and 50.0% O. The molecular mass of the compound is 93.0. What is the molecular formula of the compound? (Type your answer using the format CH4 for CH4. Keep the elements in the order given.)

Respuesta :

Answer: The molecular formula of the compound is [tex]C_3H_{12}O_3[/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 C = 37.5 g

Mass of H = 12.5 g

Mass of O = 50.0 g

Step 1 : convert given masses into moles.

Moles of C =[tex]\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{37.5g}{12g/mole}=3.125moles[/tex]

Moles of H = [tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{12.5g}{1g/mole}=12.5moles[/tex]

Moles of O = [tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{50.0g}{16g/mole}=3.125moles[/tex]

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

For C =[tex]\frac{3.125}{3.125}=1[/tex]

For H= [tex]\frac{12.5}{3.125}=4[/tex]

For O =[tex]\frac{3.125}{3.125}=1[/tex]

The ratio of C: H: O = 1: 4: 1

Hence the empirical formula is [tex]CH_4O[/tex].

The empirical weight of [tex]CH_4O[/tex] = 1(12)+4(1)+1(16)= 32g.

The molecular weight = 93.0 g/mole

Now we have to calculate the molecular formula.

[tex]n=\frac{\text{Molecular weight }}{\text{Equivalent weight}}=\frac{93}{32}=3[/tex]

The molecular formula will be=[tex]3\times CH_4O=C_3H_{12}O_3[/tex]

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