Final answer:
The empirical formulas for ionic compounds formed from the given ions are (NH4)2SO4 for ammonium sulfate and Pb(SO4)2 for lead(IV) sulfate. Cr2(SO4)3 is a compound of chromium(III) sulfate unrelated to the CrO4^2- ion. Cr2O8 is not a stable ionic compound.
Step-by-step explanation:
The student is asked to write the empirical formula for ionic compounds that could be formed from given ions. To do this, we need to ensure that the overall charge in the compound is neutralized by combining the correct ratio of cations (positively charged ions) and anions (negatively charged ions).
- The compound formed from NH4+ and SO42- is ammonium sulfate, with the formula (NH4)2SO4. Here, two ammonium ions are required to balance one sulfate ion.
- The compound formed from Pb4+ and SO42- is lead(IV) sulfate, with the formula Pb(SO4)2. Two sulfate ions are needed to balance one lead(IV) ion.
- The compound formed from CrO42- and a monovalent cation like NH4+ does not exist in the options given. However, Cr2(SO4)3 is a compound formed from Cr3+ and SO42-, chromium(III) sulfate, and it is not related to the CrO42- ion provided in the question.
- Cr2O8 is not an empirical formula for a stable ionic compound.
Correct Empirical Formulas:
(NH4)2SO4
- Pb(SO4)2
- Cr2(SO4)3
To summarize, the correct empirical formulas that can be written using the given ions are (NH4)2SO4 and Pb(SO4)2. The other formulas either do not represent stable compounds or are not correctly reflecting the ions provided in the question.