In the preparation of baking soda, H 2 O and CO 2 in ratio is used to react with Na 2 CO 3 .

Solvay process is used for the production of sodium bicarbonate and sodium carbonate industrially. In this process carbon dioxide, water, ammonia and brine solution in its concentrated form, are used as raw materials. This process is used mainly because it is inexpensive and less number of raw materials are used to produce necessary chemicals. The important chemical reaction that is used in the production of baking soda and sodium carbonate is:

$$\begin{gathered} {\mathrm{CO}}_{2 }+ {\mathrm{H}}_2\mathrm{O} + {\mathrm{NH}}_3 + \mathrm{NaCl} \to {\mathrm{NaHCO}}_3 + {\mathrm{NH}}_4\mathrm{Cl} \\ 2\mathrm{NaHCO}3 \to {\mathrm{Na}}_2{\mathrm{CO}}_3 + {\mathrm{CO}}_2 + {\mathrm{H}}_2\mathrm{O} \end{gathered}$$

Ratio of ${\mathrm{H}}_2\mathrm{O} : {\mathrm{CO}}_2=1:1$