Question

Cobalt forms two common ion oxidation states, Co+3 and Co+3. When solid cobalt is reacted with a gold (III) chloride solution, two reactions are possible, as shown in the following equations:
Reaction 1) AuCl3 (aq) + Co(s) → Au(s) + CoCl3 (aq)

Au+3(aq) + Co(s) → Au(s) + Co+3(aq)

Reaction 2) 2 AuCl3 (aq) + 3 Co(s) → 2 Au(s) + 3 CoCl2 (aq)

2 Au+3(aq) + 3 Co(s) → 2 Au(s) + 3 Co+2(aq)

Jodi reacts 6.087 grams of cobalt (MW=58.933) with a solution containing excess gold (III) chloride and recovers 13.572 g of solid gold (MW=196.967). Which reaction, 1 or 2, most likely occurred in their experiment?

Answer 1

This problem is providing us with two reactions between gold (III) chloride and cobalt in order to obtain the two possible cobalt chlorides and gold. Thus, it asks for the most feasible reaction, which is found to be the second one.

Uses of stoichiometry

In chemistry, relationships between moles and grams in chemical reactions can be studied via stoichiometry, which is based on proportional factors relating molar masses and mole ratios in chemical equations.

In this case, since we have two reactions and the same initial amount of cobalt, one can calculate the grams of solid gold, with the 1:1 mole ratio of these two in the first reaction and the 3:2 mole ratio in the second one and their atomic masses of 58.933 g/mol and 196.966 g/mol respectively:

$6.087gCo*\frac{1molCo}{58.933gCo}*\frac{1molAu}{1molCo} *\frac{196.966gAu}{1molAu}=20.34gAu\\ \\6.087gCo*\frac{1molCo}{58.933gCo}*\frac{2molAu}{3molCo} *\frac{196.966gAu}{1molAu}=13.56gAu$

Thus, since the second reaction would produce 13.56 grams of gold, and it is pretty much the same to the recovered amount of 13.572 grams, one concludes the second reaction took place in the experiment.

Learn more about stoichiometry: brainly.com/question/9743981