The ratio of [tex]Fe[/tex] to [tex] Cl_{2} [/tex] can be determined via the stoichiometric ratios of the reactants in the given equation:
[tex]2Fe+3 Cl_{2} [/tex] → [tex]2Fe Cl_{3} [/tex]
where the numbers in front of the elements/molecules are the stoichiometric ratios. Since we are concerned with the two reactants, we can say that the ratio of [tex]Fe: Cl_{2} [/tex] is equal to [tex]2:3[/tex].