[trinhn812]

In most of its ionic compounds, cobalt is either Co(II) or Co(III). One such compound, containing chloride ion and waters of hydration, was analyzed, and the following results were obtained. A 0.256-g sample of the compound was dissolved in water, and excess silver nitrate was added. The silver chloride was filtered, dried and weighed, and it had a mass of 0.308 g. A second sample of 0.416 of the compound was dissolved in water, and excess sodium hydroxide was added. The hydroxide salt was filtered and heated in a flame, forming cobalt(III) oxide. The mass of cobalt(III) oxide formed was 0.145g

a. what is the percent composition by mass of the compound?
b. Assuming the compound contains one cobalt atom per formula unit, what is the molecular formula?
c. Write a balanced equation for the three reactions described.



I think the formula starts with something like CoCl * H2O
I can't seem to get the answer for part a to (24.67% )

[Borek]

Show your work, it is hard to tell what you did wrong not knowing what you did.

[AWK]

hint
Calculate molec of CO³⁺ from a mass of Co₃O₃
Calculate moles of chlorides from a mass of AgCl.

then set system of two equation based on moles Co²⁺ and Co³⁺