# Question 9672f

Nov 4, 2016

This is a disguised double replacement reaction.

#### Explanation:

At first glance, it looks like a synthesis reaction, in which two substances combine to form a new substance.

The problem is that you can't have individual containers of $\text{Ca"^"2+}$ and of $\text{CO"_3^"2-}$.

These ions must be paired with other ions in their containers to balance the charges.

For example, you might have one container of "Ca"("NO"_3)_2 # and another of ${\text{Na"_2"CO}}_{3}$.

Even if you mixed these with each other, there would be no reaction because ionic compounds are solids.

You have to get the ions into solution so they can come into contact with each other.

The reaction will be

$\text{Ca"("NO"_3)_2"(aq)" + "Na"_2"CO"_3"(aq)" → "CaCO"_3"(s)" + "2NaNO"_3"(aq)}$

This is a double replacement reaction of the type

$\text{AB + CD → CB + AD}$

The net ionic equation for the reaction is really

$\text{Ca"^"2+""(aq)" + "CO"_3^"2-""(aq)" → "CaCO"_3"(s)}$