Question

when the polyatomic ion (so₄)²⁻ combines with the iron (iii) ion, fe³⁺, the formula for the compound is... select one: a. feso₄ b. fe₂so₄ c. fe₂(so₄)₃ d. fe₃(so₄)₂ the correct name of the compound formed from the carbonate ion, (co₃)²⁻, and the sodium ion, na⁺, is... select one: a. sodium carbide. b. sodium carbonate. c. carbonate sodide. d. carbon sodiumate.

Explanation:

Step1: Balance charges for first compound

Iron(III) ion: $\text{Fe}^{3+}$, sulfate ion: $\text{SO}_4^{2-}$. Find least common multiple of 3 and 2, which is 6. Number of $\text{Fe}^{3+}$: $\frac{6}{3}=2$, number of $\text{SO}_4^{2-}$: $\frac{6}{2}=3$. Formula: $\text{Fe}_2(\text{SO}_4)_3$

Step2: Name second ionic compound

Cation is $\text{Na}^+$ (sodium), anion is $\text{CO}_3^{2-}$ (carbonate). Ionic compound name: cation name + anion name.

Answer:

1. c. $\text{Fe}_2(\text{SO}_4)_3$
2. b. sodium carbonate