Question

What happens when aqueous solutions of calcium chloride and of sodium carbonate are mixed?

Answer 1

Hint: Write the formula of the names given and figure out the reaction taking place between the two. When there is formation of products, one of them will get precipitated and the other remains. Try to identify the name of the reaction taking place here.

Complete Step By Step Answer:
Calcium chloride $ \left( {CaC{l_2}} \right) $ and sodium carbonate $ \left( {N{a_2}C{O_3}} \right) $ are soluble ionic compounds. They easily dissolve in water. When an aqueous solution of Calcium chloride $ \left( {CaC{l_2}} \right) $ and sodium carbonate $ \left( {N{a_2}C{O_3}} \right) $ are mixed, they react with each to form an insoluble solid calcium carbonate $ \left( {CaC{O_3}} \right) $ and soluble ionic compound, sodium chloride $ \left( {NaCl} \right) $ . The product, calcium chloride $ \left( {CaC{O_3}} \right) $ precipitates out from the solution but sodium chloride $ \left( {NaCl} \right) $ gets dissolved in the solution.
The balanced chemical equation for this reaction will be as follows:
 $ CaC{l_2}_{\left( {aq} \right)} + N{a_2}C{O_3}_{\left( {aq} \right)}\xrightarrow{{}}CaC{O_3}_{\left( s \right)} \downarrow + 2NaC{l_{\left( {aq} \right)}} $
By looking at the reaction we can say that in the above reaction the cationic part of the reactant are getting displaced by each other and are getting exchanged, which is resulting in formation of new products. Hence, we can say that the above reaction is a double displacement reaction.
Therefore, when aqueous solutions of calcium chloride and of sodium carbonate are mixed, a double displacement reaction takes place.
Double displacement reactions take place in aqueous solutions in which the ions precipitate and there is an exchange of ions. The general equation for double displacement reaction is:
 $ AB + CD\xrightarrow{{}}AD + CB $ .

Note:
Double displacement reactions can be further classified as neutralization, precipitation and gas formation reactions. Double-replacement reactions generally occur between substances in aqueous solution. In order for a reaction to occur, one of the products is usually a solid precipitate, a gas, or a molecular compound such as water.