# Question Video: Writing a Net Ionic Equation for the Reaction of Solid Calcium Carbonate with a Hydrochloric Acid Solution Chemistry • 10th Grade

Rate-of-reaction experiments often use the reaction between calcium carbonate and hydrochloric acid, as shown: CaCO₃ (s) + 2 HCl (aq) ⟶ CaCl₂ (aq) + CO₂ (g) + H₂O (l). What is the net ionic equation for this reaction?

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### Video Transcript

Rate-of-reaction experiments often use the reaction between calcium carbonate and hydrochloric acid, as shown: CaCO3 solid plus two HCl aqueous react to form CaCl2 aqueous plus CO2 gas plus H2O liquid. What is the net ionic equation for this reaction?

To begin, we can identify the given balanced chemical equation as a molecular equation. A molecular equation is a chemical equation in which all reactants and products have chemical formulas of undissociated compounds. In other words, even if a compound is known to dissociate into ions in aqueous solution, in a molecular equation, these ions are not shown as being separated.

Another type of chemical equation that chemists use is an ionic equation, which separates ionic compounds and acids that are dissolved in aqueous solutions into separate ions.

Finally, a net ionic equation is a simplified ionic equation that shows only the species involved in the chemical reaction.

To answer this question, we will first need to convert our molecular equation into an ionic equation and then convert the ionic equation into a net ionic equation. To write the ionic equation, we must change the chemical formulas of the hydrochloric acid and calcium chloride solutions so that they show the dissolved ions as separate species. Two equivalents of aqueous hydrochloric acid should be written as two hydrogen ions and two chloride ions, while one equivalent of aqueous calcium chloride should be written as one calcium ion and two chloride ions.

Now that we have an ionic equation, we need to identify which species are involved in the chemical reaction. During the reaction, solid calcium carbonate dissolves in the hydrochloric acid and reacts with the hydrogen ions. Calcium ions remain dissolved in the solution, and carbon dioxide gas and liquid water are formed. The chloride ions from the hydrochloric acid do not participate in the chemical reaction and are known as spectator ions.

We know that a net ionic equation should only contain the species involved in the chemical reaction. Therefore, we should not include the chloride ions in our net ionic equation. In conclusion, the net ionic equation for the reaction between calcium carbonate and hydrochloric acid is CaCO3 solid plus two H+ aqueous react to form Ca2+ aqueous plus CO2 gas plus H2O liquid.