How do you know whether a chemical reaction is exothermic or endothermic?

Heya, does anyone know if the reaction between amylase and starch is exothermic or endothermic? or none? thnks

• thanks :0 does anyone know if the reaction between amylase and starch is exothermic or endothermic? or none? thnks

• Answer:

  Amylase is an enzyme, that is, it is a catalist for the reaction (eases and accelerates it) but does not participate in the reaction itself. Starch is a polysaccharide formed by molecules of glucose, and what happens is that starch breaks down, i.e. the bonds between these glucose molecules are hydrolized (destroyed by addition of water, H2O), resulting in smaller polysaccharids (maltose), disaccharids and eventually single glucoses (monosaccharides). This reaction releases energy, the energy that was previously stored in those chemical bonds during the synthesis of starch; thus, it's exergonic (in fact all breakdown reactions - catabolism- are exergonic/exothermic).