Final answer:
When iron (III) nitrate and sodium carbonate are mixed, iron (III) carbonate, with the formula Fe₂(CO₃)₃, precipitates.
Step-by-step explanation:
If solutions of iron (III) nitrate and sodium carbonate are mixed, the formula of the precipitate formed would be Fe₂(CO₃)₃. This is because iron (III) nitrate, Fe(NO3)3, can dissociate into Fe³⁺ and NO3⁻ ions in the solution, and sodium carbonate, Na2CO3, can dissociate into Na⁺ and CO3²⁻ ions. When these two solutions are mixed, the Fe³⁺ ions would react with CO3²⁻ ions to form iron (III) carbonate, which is an insoluble compound and hence will precipitate out of the solution. The equation for this reaction is:
2 Fe(NO3)₃ (aq) + 3 Na₂CO₃ (aq) → Fe₂(CO₃)₃ (s) + 6 NaNO₃ (aq)
Therefore, the correct answer is B. Fe₂(CO₃)₃.