What precipitate will form when aqueous solutions of sodium carbonate calcium Na_2CO_3 and calcium chloride CaCl_2 are mixed?

Mar 31, 2016

Calcium carbonate.

Explanation:

Sodium carbonate, ${\text{Na"_2"CO}}_{3}$, and calcium chloride, ${\text{CaCl}}_{2}$, are soluble ionic compounds that dissociate in aqueous solution to form cations and anions.

You can thus say that the sodium carbonate solution will contain sodium cations, ${\text{Na}}^{+}$, and carbonate anions, ${\text{CO}}_{3}^{2 -}$

${\text{Na"_ 2"CO"_ (3(aq)) -> 2"Na"_ ((aq))^(+) + "CO}}_{3 \left(a q\right)}^{2 -}$

Likewise, the calcium chloride solution will contain calcium cations, ${\text{Ca}}^{2 +}$, and chloride anions, ${\text{Cl}}^{-}$

${\text{CaCl"_ (2(aq)) -> "Ca"_ ((aq))^(2+) + 2"Cl}}_{\left(a q\right)}^{-}$

Now, when you mix these two solutions, the calcium cations will pair up with the carbonate anions and for calcium carbonate, ${\text{CaCO}}_{3}$, an insoluble ionic compound that precipitates out of solution. This double replacement reaction will also produce aqueous sodium chloride.

The complete ionic equation looks like this

$2 {\text{Na"_ ((aq))^(+) + "CO"_ (3(aq))^(2-) + "Ca"_ ((aq))^(2+) + 2"Cl"_ ((aq))^(-) -> "CaCO"_ (3(s)) darr + 2"Na"_ ((aq))^(+) + 2"Cl}}_{\left(a q\right)}^{-}$

Eliminate the spectator ions

$\textcolor{red}{\cancel{\textcolor{b l a c k}{2 {\text{Na"_ ((aq))^(+)))) + "CO"_ (3(aq))^(2-) + "Ca"_ ((aq))^(2+) + color(red)(cancel(color(black)(2"Cl"_ ((aq))^(-)))) -> "CaCO"_ (3(s)) darr + color(red)(cancel(color(black)(2"Na"_ ((aq))^(+)))) + color(red)(cancel(color(black)(2"Cl}}_{\left(a q\right)}^{-}}}}$

to get the net ionic equation

${\text{CO"_ (3(aq))^(2-) + "Ca"_ ((aq))^(2+) -> "CaCO}}_{3 \left(s\right)} \downarrow$