What is the empirical formula of a compound that contains 15.77% aluminum, 28.11% sulfur and 56.12% oxygen

Al₂(SO₄)₃

We are given percentage composition of elements in a compound;

We are required to calculate the empirical formula of the compound.

Aluminium = 15.77 g

Sulfur = 28.11

Oxygen = 56.12

We can determine the number of moles of each;

Moles of Aluminium = 15.77 g ÷ 26.98 g/mol

                                 = 0.585 moles

Moles of sulfur = 28.11 g ÷ 32.07 g/mol

                         = 0.877 moles

Moles of Oxygen = 56.12 g ÷ 16.0 g/mol

                            = 3.5075 moles

Aluminium : Sulfur : Oxygen

0.585 mol  :  0.877 mol : 3.5075 mol

0.585/0.585 : 0.877/0.585 : 3.5075/0.585

    1 : 1.5 : 6

But, we need whole number ratios, therefore;

= (1 : 1.5 : 6 ) × 2

= 2 : 3 : 12

Therefore; the formula of the compound is Al₂S₃O₁₂

The compound is written as Al₂(SO₄)₃

Thus, the empirical formula of the compound is Al₂(SO₄)₃

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.