A compound has the empirical formula CoCl₃ ∙ 5NH₃. One mole of it yields two moles of silver chloride when treated with silver nitrate. Ammonia is not removed by treatment with concentrated sulfuric acid. A reasonable formula for the compound is ________. A) [Co(NH₃)₅]Cl₃ B) CoCl₃ ∙ 5NH₃ C) [Co(NH₃)₄Cl]Cl₂ ∙ NH₃ D) [Co(NH₃)₅Cl]Cl₂ E) [Co(NH₃)₄Cl₂]Cl ∙ NH₃

Question

Quizplus · Accepted Answer

The empirical formula can be simplified to CoClSBU∙5NHSBU, where "BU" represents the subscripts 1 and 3 alternating. 
When the compound is treated with silver nitrate, it yields two moles of silver chloride, indicating that there are two chloride ions associated with each formula unit. This rules out choices A, C, and E, which have additional chloride ions in the formula. 
The fact that ammonia is not removed by treatment with concentrated sulfuric acid suggests that the compound contains a coordinated amine ligand, which is present in all of the answer choices. However, choice D is the only one that has the correct ratio of chloride ions to Co, S, and N atoms in the empirical formula, and also fits the experimental evidence provided.

A Compound Has the Empirical Formula CoCl3 ∙ 5NH3

A Compound Has the Empirical Formula CoCl₃ ∙ 5NH₃