Maleic acid is an organic compound composed of 41.39% C, 3.47% H, and the rest oxygen. If 0.129 mole of maleic acid has a mass of 15.0 g, what are the empirical and molecular formulas of maleic acid?

Molecular formula → C₄H₄O₄

Empircal formula → CHO

Explanation:

The centesimal composition for the maleic acid is:

41.39 g / 100 g of maleic acid → C

3.47 g / 100 g of maleic acid → H

100 - (41.39 + 3.47) / 100 g of maleic acid → 55.14 g / 100 g of maleic acid → O

Let's determine the molar mass (g/mol) → 15 g / 0.129 mol = 116.2 g/mol

So, we must do these rules of three:

100 g of maleic acid have 41.39 g of C, 3.47 g of H and 55.14 g of O

Therefore, 116.2 g  of maleic must have:

(116.2 . 41.39) / 100 = 48 g of C

(116.2 . 3.47) / 100 = 4 g of H

(116.2 . 55.14) / 100 = 64 g of O

We convert the mass to moles:

48 g . 1mol / 12 g = 4 moles of C

4 g . 1mol / 1g  = 4 moles of H

64 g . 1mol / 16 g = 4 moles of O

Molecular formula → C₄H₄O₄

Empircal formula → We can divide the sub-index by 4 to reach the lowest coefficients → CHO

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