# How do we represent the reaction of hydrochloric acid with stoichiometric calcium carbonate? Do we need to consider oxidation states?

May 27, 2017

This is an acid-base reaction, in which no redox transfer occurs........

#### Explanation:

We can write out the stoichiometric equation:

$C a C {O}_{3} \left(s\right) + 2 H C l \left(a q\right) \rightarrow C a C {l}_{2} \left(a q\right) + C {O}_{2} \left(g\right) + {H}_{2} O \left(l\right)$

And the net ionic equation:

$C {O}_{3}^{2 -} + 2 {H}_{3} {O}^{+} \rightarrow C {O}_{2} \left(g\right) \uparrow + 3 {H}_{2} O \left(l\right)$

And we can include oxidation numbers on reactants and products:

$\stackrel{+ I V}{C} {O}_{3}^{2 -} + 2 {H}_{3} {O}^{+} \rightarrow \stackrel{+ I V}{C} {O}_{2} \left(g\right) \uparrow + 3 {H}_{2} O \left(l\right)$

Are these equations balanced with respect to mass and charge? They need to be if we purport to represent chemical reality!

The oxidation numbers of hydrogen and carbon remain at $\stackrel{- I I}{O}$ and $\stackrel{+ I}{H}$ respectively.