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Silver nitrate solution is mixed with sodium fluoride solution. What is predicted, and why?
ANo reaction, since every fluoride salt dissolves
BNo reaction, since every silver salt dissolves well
CAgF precipitates, since it is a fluoride exception
DNaNO3 precipitates, since nitrates are insoluble
Answer & Solution
Correct answer: C. AgF precipitates, since it is a fluoride exception
1. The mixed solution holds Ag+, NO3-, Na+ and F- ions.
2. Besides the two starting salts, the possible new compounds are NaNO3 and AgF.
3. All nitrate salts are soluble, so NaNO3 stays dissolved.
4. Fluoride salts are generally soluble, but AgF is named among the exceptions.
5. So a precipitate of AgF is predicted, with net ionic equation Ag+ plus F- giving AgF(s).
6. Saying all fluorides dissolve ignores the exception list.
7. Saying nitrates precipitate contradicts the guideline that nitrates carry no exceptions.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 4 "Stoichiometry of Chemical Reactions", section 4.2 Classifying Chemical Reactions_
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