Baking soda is sodium hydrogen carbonate:`NaHCO_3`
When it reacts with acid it undergoes both neutralization to produce water and the salt sodium acetate, and decomposition of the hydrogen carbonate ion to produce carbon dioxide gas. Here's an equation for sodium hydrogen carbonate reacting with acetic acid (vinegar):
`NaHCO_3_(s) + HCH_3COO_(aq) -> NaCH_3COO_(aq) + CO_2_(g) + H_2O`
In general, the reaction with an acid is:
`NaHCO_3 + H^+ -> Na^+ + CO_2 + H_2O`
You could write this equation using any acid. The acid's anion (negative ion) will form a salt with the acetate ion, CH3COO-. All acetate compounds are soluble so they are written in the ionic form or with the subscript aq meaning dissolved in aqueous solution.
Sodium hydrogen carbonate also decomposes to produce carbon dioxide when heated. It's used in baking because the CO2 bubbles get trapped in dough and cause it to rise in the oven.