Question

What happens when carbonates react with acid?

Answer 1

Hint: First we will write the correct chemical formula of the reactants and find out their ion’s oxidation state. By oxidation state and their charges, we can predict the product. The reaction is similar to the neutralization reaction except an extra product is formed in this.

Complete step by step answer:
We all know how an acid dissociates into its ions
${\text{HCl }} \to {\text{ }}{{\text{H}}^{\text{ + }}}{\text{ + C}}{{\text{l}}^{\text{ - }}}$
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}{\text{ }} \to {\text{ 2}}{{\text{H}}^{\text{ + }}}{\text{ + S}}{{\text{O}}_{\text{4}}}^{{\text{2 - }}}$
\[{\text{HN}}{{\text{O}}_{\text{3}}}{\text{ }} \to {\text{ }}{{\text{H}}^{\text{ + }}}{\text{ + N}}{{\text{O}}_{\text{3}}}^{\text{ - }}\]

These protons are characteristic of acid. The acid is used as a test of carbonate or carbonate can be used as a test of acid vice-versa. When we add any metal carbonate to an acidic solution, evolution of bubbles of carbon-dioxide are evidently released. This effervescence of carbon-dioxide is a confirmatory test for acids.

${\text{Acid + Metal Carbonate }} \to {\text{ Salt + Water + C}}{{\text{O}}_{\text{2}}}$

This is the main headline of the reaction. If we take one of the acids from above and any metal carbonate for example- ${\text{CaC}}{{\text{O}}_{\text{3}}}$ (calcium carbonate).

${\text{2HC}}{{\text{l}}_{{\text{(aq)}}}}{\text{ + CaC}}{{\text{O}}_{\text{3}}}_{{\text{(s)}}}{\text{ }} \to {\text{ CaC}}{{\text{l}}_{{\text{2(aq)}}}}{\text{ + }}{{\text{H}}_{\text{2}}}{{\text{O}}_{{\text{(l)}}}}{\text{ + C}}{{\text{O}}_{{\text{2(g)}}}}$

When an acid reacts with any carbonate there is a brisk effervescence of carbon-dioxide released from the reaction container.


Additional information:
When geologists and archaeologists excavate any new sites there are a whole lot of tests done to confirm the chemicals or substances used at that time or the rocks present at that site. Acid is used to know the type of rock present at the site. Little amount of acid solution is dropped on the rock and if there are bubbles of gas emerging from that surface then it is a carbonate rock.

Note: This reaction is similar to neutralization reaction in which acid and base react to give salt and water, the only difference is there is an additional product carbon-dioxide also released.