#1: Determine the possible products using the general double displacement equation.
AB + CD
AD + CB
In AgNO3, Ag+ is A, and NO3- is B. In
Na2S, Na+ is C, and S2- is D. The possible products from the mixture of
AgNO3(aq) and Na2S(aq) are Ag2S and NaNO3. (Remember to consider charge when you determine the formulas for
the possible products.)
AgNO3(aq) + Na2S(aq) to
Ag2S and NaNO3
Step #2: Predict whether either of the possible products is water insoluble.
According to our solubility guidelines, most sulfides are
insoluble, and compounds with Ag+ are not listed as an exception. Therefore,
Ag2S would be insoluble. Silver sulfide is used to make ceramics. Because
compounds containing Na+ and NO3- are soluble,
NaNO3 is soluble.
Step #3: Write
the complete equation. (Dont forget to balance the equation.)
2AgNO3(aq) + Na2S(aq)
Ag2S(s) + 2NaNO3(aq)
Step #4: Write the net ionic equation.
Write the complete ionic equation, describing the aqueous
ionic compounds, AgNO3(aq), Na2S(aq) and NaNO3(aq), as ions. Describe the solid
with a complete formula.
2Ag+(aq) + 2NO3-(aq) +
Ag2S(s) + 2Na+(aq) + 2NO3-(aq)
The nitrate and sodium ions have the same form on each side
of the equation, so they are eliminated as spectator ions.
2Ag+(aq) + S2-(aq)