Question

When does a precipitation reaction occur?

• A. When the cations of one reactant and the anions of a second reactant found in aqueous solutions combine to form an insoluble ionic solid.
• B. When the cations of one reactant and the anions of the same reactant found in aqueous solutions combine to form an insoluble ionic solid.
• C. When the cations of one reactant and the cations of a second reactant found in aqueous solutions combine to form an insoluble ionic solid.
• D. When the equation is balanced and only the net ionic charges are shown.
• E. When the equation is written so only those substances participating in the reaction are shown.

Answer 1

The correct option is A When the cations of one reactant and the anions of a second reactant found in aqueous solutions combine to form an insoluble ionic solid.

A precipitation reaction occur when the cations of one reactant and the anions of a second reactant found in aqueous solutions combine to form an insoluble ionic solid.
For example, magnesium ions combine with carbonate ions to form ppt of magnesium carbonate.
$M{g}^{2+}\left(aq\right)+C{O}_3^{2-}\left(aq\right)\to MgCO3\left(s\right)$