How to balance complicated chemical equations?

Jul 29, 2017

Every chemical equation balances MASS and CHARGE.......

Explanation:

You gots a metal carbonate, say $Z n C {O}_{3} \left(s\right)$:

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

Are mass and charge balanced here? If they are not then you cannot accept the equation as a representation of chemical reality. And if you start with $10 \cdot g$ of reactant from all sources, you inevitably finish with $10 \cdot g$ product.......

The lesson that I try to reinforce is that $\text{mass and charge are CONSERVED}$.

Carbonates (and these are often insoluble salts) react with acids according to the following net ionic equation......

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

You simply have to know these reactions, and how to balance them stoichiometrically.

And likewise for bicarbonates......

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

Bicarbonate salts TEND to be soluble. Carbonate salts tend to be insoluble. But this is the province of experiment.