[zain]

Hey guys..
I was revising using a past paper.
and i found a question that I had a problem with. my university does not give answers with past papers so i don't have a clue whether i'm doing it correctly

"C(i): Write a balanced chemical equation, and a balanced ionic equation, for the neutralisation reaction between sodium carbonate and hydrochloric acid."

As far as I have deduced I have found 2 possible solutions:
1. Na2CO3 + 2HCl --> H2 + 2NaCl + CO2 + 1/2O2

or 2. Na2CO3 + 2HCl --> H2CO3 + 2NaCl

if someone could give me the real answer or check my answers that would be great.
Thanks very much. Zain

[Donaldson Tan]

Both equations are wrong.

Here's a hint: neutralisation of carbonates produces carbon dioxide and water.

[zain]

Both equations are wrong.

Here's a hint: neutralisation of carbonates produces carbon dioxide and water.

oh wow. i love how u handled that... rather than telling me the answer!...
i think i have it now...

Na2CO3 + 2HCl --> CO2 + H2O + 2NaCl
can anyone confirm that?
the thing is... we questions on Carbonates once in a blue moon... and we've never been taught them.
its just silly really.
but many thanks!

[Borek]

Na2CO3 + 2HCl --> CO2 + H2O + 2NaCl

OK, although reality is more complicated - it is ionic equilibrium with several steps.

[zain]

Na2CO3 + 2HCl --> CO2 + H2O + 2NaCl

OK, although reality is more complicated - it is ionic equilibrium with several steps.

oh yes i have to do an ionic as well.
although this is easy

2Na+  + CO3- + 2H+ + 2Cl- ----> CO2 + H2O + 2Na+ + Cl-

so therefore.. CO3- + 2H+ --> CO2 + H2O

is this correct?

[Yggdrasil]

Both are correct.  The process is somewhat more complicated (as mentioned by Borek) because it involves the following equilibria:

CO₃^2- + H⁺ <--> HCO₃^-

HCO₃^- + H⁺ <--> H₂CO₃

H₂CO₃ <--> H₂O + CO₂

Since CO₂ is a gas, it will escape, driving the equilibrium toward the production of CO₂ and H₂ in the presence of excess acid.  However, when acid is the limiting reagent, you will need to consider the production of bicarbonate and carbonic acid in addition to CO₂

[Donaldson Tan]

Correction:

Since CO₂ is a gas, it will escape, driving the equilibrium toward the production of CO₂ and H₂O in the presence of excess acid.

Also take in account take HCl is a strong acid.