# How do you represent the loss of carbon dioxide from soda lime, Na_2CO_3?

I think you mean the loss, the decarboxylation, of $C {O}_{2}$ from $N {a}_{2} C {O}_{3}$.
But, $N {a}_{2} C {O}_{3}$ is NOT $\text{SODA LIME}$. Soda lime is the product, $N {a}_{2} O$ and its hydroxides, and it is obtained from $\text{decarboxylation}$ of sodium carbonate:
$N {a}_{2} C {O}_{3} \left(s\right) + \Delta \rightarrow N {a}_{2} O \left(s\right) + C {O}_{2} \left(g\right) \uparrow$