A compound is found to contain 59.94 % carbon , 13.44 % hydrogen , and 26.62 % oxygen by mass.

(1) The empirical formula for this compound is ____ .
(2) The molecular weight for this compound is 60.11 amu. The molecular formula for this compound is ____.

Respuesta :

Answer : (1) The empirical formula of a compound is, [tex]C_3H_8CO[/tex]

(2) The molecular formula of a compound is, [tex]C_3H_8CO[/tex]

Solution :

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 = 59.94 g

Mass of H = 13.44 g

Mass of O = 26.62 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of O = 16 g/mole

Step 1 : convert given masses into moles.

Moles of C = [tex]\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{59.94g}{12g/mole}=4.995moles[/tex]

Moles of H = [tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{13.44g}{1g/mole}=13.44moles[/tex]

Moles of O = [tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{26.62g}{16g/mole}=1.664moles[/tex]

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

For C = [tex]\frac{4.995}{1.664}=3.00\approx 3[/tex]

For H = [tex]\frac{13.44}{1.664}=8.07\approx 8[/tex]

For O = [tex]\frac{1.664}{1.664}=1[/tex]

The ratio of C : H : O = 3 : 8 : 1

The mole ratio of the element is represented by subscripts in empirical formula.

The Empirical formula = [tex]C_3H_8CO_1=C_3H_8CO[/tex]

The empirical formula weight = 3(12) + 8(1) + 1(16) = 60 gram/eq

Now we have to calculate the molecular formula of the compound.

Formula used :

[tex]n=\frac{\text{Molecular formula}}{\text{Empirical formula weight}}[/tex]

[tex]n=\frac{60.11}{60}=1[/tex]

Molecular formula = [tex](C_3H_8CO)_n=(C_3H_8CO)_1=C_3H_8CO[/tex]

Therefore, the molecular of the compound is, [tex]C_3H_8CO[/tex]