Ionic Equations ????

Question

I need a step by step guide on ionic equations (have have no idea how the charges change)- e.g.
CaCo3 + HNO3 ---> Ca(NO3)2 + CO2 + H2O

Answer 1

First balance eq., and write out your dissolved salts and strong acids as ions;

CaCO3(s) + 2H+(aq) + 2NO3-(aq) >>> Ca2+(aq) + 2 NO3-(aq) + CO2(g) + H2O(l)

Then for the NET ionic eq., subtract those things (in this case, NO3- is the only one) that are merely spectator ions, sitting there in solution eating hot dogs and not taking part in the action.

Things to watch: write out solids, liquids, and gases as such, even ionic solids, because the ions in CaCO3, for example, are not independent of each other. Write out weak acids (e.g. acetic acid) in their undissociated form. And of course, if the equation wasn't balanced to start with, it won't be to finish with either.

Hope this helps.

Answer 2

CaCO3(aq) + 2HNO3(aq) --> Ca+2(aq) + CO3-2(aq) + 2H+(aq) + 2NO3-(aq)

Ca+2(aq) + 2NO3-(aq) --> Ca(NO3)2 so that is where that comes from

2H+(aq) + CO3-2(aq) --> H2CO3(aq) but this is unstable and decomposes to CO2 and H2O

H2CO3(aq) --> CO2(g) + H2O(l)

so your final ionic equation becomes:

Ca+2(aq) + CO3-2(aq) + 2H+(aq) + 2NO3-(aq) -->

Ca(NO3)2(aq) (or Ca+2(aq) + 2NO3-2(aq)) + CO2(g) + H2O(l)

the net ionic equation is:

2H+(aq) + CO3-2(aq) --> CO2(g) + H2O(l)