The law of constant composition implies that in the decomposition of iron(III) chloride, a fixed ratio of iron to chlorine is maintained, resulting in the production of 1 mole of iron for every 3 moles of chlorine.
The law of constant composition, also known as the law of definite proportions, states that a given chemical compound always contains the same elements in the same proportion by mass, regardless of the source or method of preparation. In the case of iron(III) chloride (FeCl₃), it consists of one iron (Fe) atom for every three chlorine (Cl) atoms
Upon the decomposition of iron(III) chloride, the chemical reaction is represented as:
→
This balanced equation illustrates that for every two moles of iron(III) chloride decomposed, two moles of iron are produced alongside three moles of chlorine gas. The law of constant composition ensures that the ratio of iron to chlorine remains fixed, resulting in the consistent production of one mole of iron for every three moles of chlorine in the decomposition of iron(III) chloride.