Exothermic is the release of heat. Exo as in exit to leave and thermos, the Greek word for heat. Endothermic is the absorption of heat. So if a chemical reaction is exothermic the reaction loses heat and it feels warm to you. If it is endothermic, it absorbs heat. If you are holding a beaker with an endothermic reaction, it will absorb the heat from you and therefore these re
actions feel cool to touch!
When a fuel burns, it combines with oxygen int the air and changes into the substances water and carbon dioxide. That's how Flammability is a chemical property.
If you were to compare the mass of the products and reactants in a reaction, you would find that the mass of the products is <span>equal to the mass of the reactants.</span>