[sunshower]

Hi

I was wondering if anyone could please show me how to show that the reaction between an acid and a carbonate in which carbon dioxide is produced, is an acid base reaction using the Lowry Bronsted definition.

Thank you very much

sunshower

[Borek]

Write reaction equation and Bronsted Lowry  definition, we will try to combine them later

[AWK]

eg, in anology to
SO₃^2- + H₃O⁺ = HSO₃^- + H₂O
HSO₃^- + H₃O⁺ = H₂SO₃ + H₂O
H₂SO₃ = SO₂ + H₂O

[sunshower]

Hi Awk and Borek

Thank you for your help. I should have explained it more. The question actually said:

Is the following reaction

H₂SO₄ + CaCO₃   --->  CaSO₄ + H₂O  +  CO₂ 

redox, acid/base, both or neither.

I'm happy about the redox part (it's not) and am sure it is an acid/base reaction too, but am not sure how to explain to my students how to spot it.

We define an acid as a proton donor and a base as a proton acceptor.

If I look at the ionic equation

2H⁺  +CO₃^2- --> H₂O  + CO₂

I can't see it as a proton transfer then either.

All the best

sunshower

[Borek]

If I look at the ionic equation

2H⁺  +CO₃^2- --> H₂O  + CO₂

I can't see it as a proton transfer then either.

That's because there are several steps here.

H⁺ + CO₃^2- <-> HCO₃^-

HCO₃^- + H⁺ <-> H₂CO₃

and finally decomposition of the carbonic acid:

H₂CO₃ <-> CO₂ + H₂O

First two are obviously protonations, last one is... well, just decomposition. Each reaction with its own equlibrium, last one shifted to the right so that the amount of the carbonic acid present in water solution is minute. This acid is realatively strong, thus it easily dissociates. Things is, we always treat two reactions together, describing them with one dissociation constant, as amounts of acid are very small resulting constant is low, so everyone thinks that carbonic acid is a weak one.

[sunshower]

Thank you very much Borek. That is very helpful.

sunshower