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Carbonate, chromate, phosphate and sulfide compounds are generally insoluble. What is the listed exception?
ATheir compounds with silver and lead ions
BTheir compounds with all group 2 cations
CTheir compounds with iron and copper ions
DTheir compounds with group 1 and ammonium ions
Answer & Solution
Correct answer: D. Their compounds with group 1 and ammonium ions
1. The guidelines place carbonate, chromate, phosphate and sulfide in the insoluble column.
2. The exception given is that these anions do dissolve when paired with group 1 cations or with ammonium.
3. So sodium carbonate dissolves while lead carbonate does not.
4. Silver and lead compounds of these anions follow the general rule and stay insoluble.
5. That is why lead nitrate plus ammonium carbonate gives a PbCO3 precipitate.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 4 "Stoichiometry of Chemical Reactions", section 4.2 Classifying Chemical Reactions_
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