To clean their drain pipes, some people make a solution of baking soda and vinegar. Baking soda, also known as sodium bicarbonate (NaHCO3), reacts with acetic acid (C2H4O2) in vinegar. When these substances combine, the solution becomes colder, and sodium acetate (NaC2H3O2), water (H2O), and carbon dioxide gas (CO2) form. The gas creates bubbles that help clean the inside of the pipes. is this reaction endothermic or exothermic?