Question

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

Answer 1

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

Explanation:

We can write out the stoichiometric equation:

`CaCO_3(s) + 2HCl(aq) rarr CaCl_2(aq) + CO_2(g) +H_2O(l)`

And the net ionic equation:

`CO_3^(2-) + 2H_3O^(+) rarr CO_2(g)uarr +3H_2O(l)`

And we can include oxidation numbers on reactants and products:

`stackrel(+IV)CO_3^(2-) + 2H_3O^(+) rarr stackrel(+IV)CO_2(g)uarr +3H_2O(l)`

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(-II)O` and `stackrel(+I)H` respectively.