Acetic acid is an organic compound composed of 40.00% c, 6.71% h, and the rest oxygen. if 0.234 mol of acetic acid has a mass of 14.1 g, what are the empirical and molecular formulas of acetic acid?

Answer : The empirical and molecular formulas of acetic acid is,  and respectively.

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 = 40.00 g

Mass of H = 6.71 g

Mass of O = 100 - (40.00+6.71) = 53.29 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 =

Moles of H =

Moles of O =

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

For C =

For H =

For O =

The ratio of C : H : O = 1 : 2 : 1

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

The Empirical formula =

The empirical formula weight = 1(12) + 2(1) + 1(16) = 30 gram/eq

Now we have to calculate the molar mass of acetic acid.

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

Formula used :

Molecular formula =

Therefore, the empirical and molecular formulas of acetic acid is,  and respectively.

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