In most of its ionic compunds cobalt is either Co(II) or Co(III). One such compo

Question

In most of its ionic compunds cobalt is either Co(II) or Co(III). One such compound containing chloride ion and water of hydration, was analyzed, and the following results were obtained. A 0.256g 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 0.308g. A second sample of 0.416g of the compound was dissolved in water and an excess of sodium hydroxide was added. The hydroxide salt was filtered and heat in a flame forming cobalt(III) oxide. The mass of cobalt (III)oxide was 0.145g. A. What is the % composition by mass of the compound? B. Assuming the compound contains one cobalt ion per formula unit what is the formula? C. Write a balanced chemical for each of the three reactions described. PLEASE HELP AND SHOW WORK

Explanation / Answer

moles AgCl = 0.308 g /143.32 g/mol=0.00215 = moles Cl- in 0.256 g of the compound Moles Co2O3 = 0.145 g / 165.86 g/mol=0.000874 Moles Co3+ = 0.000874 x 2 = 0.00175 in 0.416 g moles Cl- in 0.416 g = 0.00215 x 0.416/ 0.256 = 0.00349 mass Co = 0.00175 x 58.933 g/mol= 0.103 g mass Cl = 0.00349 x 35.453 g/mol=0.124 g % Co = 0.103 x 100/ 0.416=24.8 % Cl = 0.124 x 100/ 0.416=29.8 0.00175 / 0.00175 =1 => Co 0.00349 / 0.00175 = 2 = > Cl CoCl2 CoCl2 + 2 AgNO3 = 2 AgCl + Co(NO3)2 CoCl2 + 2 NaOH = Co(OH)2 + 2 NaCl 4 Co(OH)2 + O2 = 2 Co2O3 + 4 H2O

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.