Sodium hydrogen carbonate is also known as sodium bicarbonate and it reacts with acetic acid to give sodium acetate and carbon dioxide gas is evolved as this gas is confirmed when it turns lime water milky. This is a confirmatory test for carboxylic acids.
NaHCO3+ CH3COOH ⟶ CH3COONa + CO2 + H2O
This is a double displacement reaction because the Na is displaced with the H of CH₃COOH. There is a decomposition reaction also, because one substance is converted into two different substances.
H₂CO₃(aq) → CO₂(g) + H₂O(l)