Physical and Chemical Changes
By Lara Segovia & Logan Saul
Chemical changes happen when a substance mixes with another substance to create a new substance, called synthesis or, alternatively, decomposes into two or more different substances. These processes are called chemical reactions and are not reversible except by further chemical reactions. Some reactions produce heat and others may require heat to turn on to occur, which are called endothermic reactions. Understanding chemical changes is a big part of the science of chemistry.