Does a precipitate form when a solution of sodium acetate and a solution of ammonium sulfate are mixed together?

Feb 23, 2018

No, it does not.

Explanation:

The idea here is that you're mixing two solutions that contain soluble ionic compounds and you're interested in finding out if an insoluble ionic compound can be formed by the reaction.

Sodium acetate and ammonium sulfate are both soluble ionic compounds, which implies that they exist as ions in aqueous solution.

${\text{CH"_ 3"COONa"_ ((aq)) -> "CH"_ 3"COO"_ ((aq))^(-) + "Na}}_{\left(a q\right)}^{+}$

("NH"_ 4)_ 2"SO"_ (4(aq)) -> 2"NH"_ (4(aq))^(+) + "SO"_ (4(aq))^(2-)

Now, the two products that can be formed here are ammonium acetate, $\text{NH"_ 4"CH"_ 3"COOH}$, and sodium sulfate, ${\text{Na"_ 2"SO}}_{4}$.

According to the solubility rules, which you can find listed here, both of these compounds are soluble in water, which implies that they exist as ions in aqueous solution.

Ammonium acetate is soluble because there are no anions that can form an insoluble solid with this cation. Similarly, sodium acetate is soluble because there are no anions that can form an insoluble solid with the sodium cation.

So if you start with all four ions present as such in aqueous solution and end up the same way, then you can't say that this reaction will not produce an insoluble solid that can precipitate out of the solution.

Consequently, you can say that this double-replacement reaction does not take place.

"CH"_ 3"COONa"_ ((aq)) + "Na"_ 2 "SO"_ (4(aq)) -> color(red)("N. R.")

To show that this is the case, you can write the complete ionic equation.

2 xx ["CH"_ 3"COO"_ ((aq))^(-) + "Na"_ ((aq))^(+)] + 2"NH"_ (4(aq))^(+) + "SO"_ (4(aq))^(2-) -> 2"NH"_ (4(aq))^(+) + 2"CH"_ 3"COO"_ ((aq))^(-) + 2"Na"_ ((aq))^(+) + "SO"_ (4(aq))^(2-)

The fact that all four ions are spectator ions, i.e. they are present on both sides of the equation, tells you that the reaction does not take place.