Question

Maleic acid is an organic compound composed of 41.39% C, 3.47% H, and 55.14% O. If 0.129 mole of Maleic acid has a mass of 15.0 g, what are the empirical and molecular formulas of Maleic acid?

Answer 1

Let us consider we have 100 g
C is 41.39 % of the sample = 41.39 g
H is 3.47 % of the sample = 3.47 g
O is the rest = 55.14 g

Now determine moles of each

moles = mass / molar mass
molar mass C = 12.01 g/mol
molar mass H = 1.008 g
molar mass O = 16.00 g/mol

moles C = 41.39 g / 12.01 g/mol = 3.4463 mol
moles H = 3.47 g / 1.008 g/mol = 3.4425 mol
moles O = 55.14 g / 16.00 g/mol = 3.446 mol

So the ratio of
mol C : mol H : mol O
= 3.4463 mol : 3.4425 mol : 3.446

To get it to its simplest form divide each number by the lowest number

(3.4463 / 3.4425) : (3.4425 / 3.4425) : (3.446 / 3.4425)
= 1 : 1 : 1

The empirical formula is
CHO