Part 5 of Chapter 1 in Chemistry

Service Description

as mentioned in the last lesson chemical changes are always accompanied by energy changes stating the are two types: that given off in the form of heat or light with an automatic Exothermic energy and the other is slower and must absorb the energy given in the form of Endothermic Energy. The book shoes this through two different figures. One Figure shows the energy upward as the other figure does also and the Reaction time going to the right. The reactants moved at the same time. However, the in the first figure showing the Exothermic Energy the reactants are high in energy and the activation energy is small and the products are small with the products low in energy. The second figure shows Endothermic Energy with the reactants of a small amount of energy small energy moving the energy to the products even before it comes to the activation energy and the activation energy reaches clear from the reactants past the products line and to the top meaning the energy is large. The products are high in energy at the end when they started out low in energy at first. The term 'activation energy' is used. For it is the energy necessary to get the reaction going by increasing the energy of the reactants so they can combine. the book points out one must heat paper for it to burn. This heat raises the energy of the reactants so that the burning can begin; then enough energy is given off from the burning so that an external source of energy is no longer necessary. Then the book talks about the Conservation of Mass in which the book states, "When ordinary chemical Changes occur, the mass of the reactants equals the mass of the products. This can be stated another way: In a chemical change, matter can neither be created nor destroyed, but only changed from one to another. This is referred to as the 'Law of Conservation of Matter(Lavoisier---1785)'. This law is extended by the Einstein mass-energy relationship, which states that matter and energy are interchangeable (see pag 9)." The next lesson will be on Energy.