Consider the unbalanced chemical equation.
Al(s) + Cl2(g) → AlCl3(s)
A student tries to balance the equation by changing the subscript 2 on Cl to a 3. Explain why this is not correct. What is the correct balanced equation?
A molecule is the the smallest part of a substance that can exist freely. Substances always take part in chemical reactions in the form of molecules. Gases like hydrogen, nitrogen, oxygen and chlorine generally exist as diatomic molecules- H2, N2, O2, Cl2.
Hence Cl can not be exist has Cl3, as it is a diatomic molecule, thus the changing of the subscript from 2 to 3 is incorrect.