The text, bottom of page 105-top of 106 (Volume I, 2nd ed.) states that the chemical reaction of baking soda and vinegar to producing carbon dioxide releases heat energy and gets hot. This is an error. Heat from the environment drives this reaction, hence it absorbs heat and the temperature is seen/felt to drop. This does not affect the basic concept being emphasized: making a mixture does not change the nature of the particles involved, nor does it involve the absorption or release of energy. A chemical reaction invariably does both. The chemical reaction ends up with different materials and energy enters of leaves the reaction.
Thanks for this clarification! We had fun measuring the temperature change of the baking soda-vinegar reaction, and used it as evidence that a chemical reaction can cause temperature change either way.
We use single-use hand warmers as evidence of a chemical reaction causing heat release, and talked about oxidation.