Energy consists of Heat and Work 2. How can the energy go up OR down. I thought I learned that energy was conserved and remained the same. A. Energy IS conserved, but only when considering System AND Surroundings. In the case of a car engine the system of the engine is surrounded by the environment and and energy changes in the system will be offset by compensating changes in the surroundings.
Chemistry is the study of changes in matter.
We observe these changes in the macroscopic world - an auto burns gasoline through a series of millions of individual combustions and the car moves down the road. But there is a corresponding microscopic place in which individual molecules of octane begin to break down by reaction with oxygen and yield, molecule by molecule, water and carbon dioxide. The challenge of science learners is to keep these macro and microscopic views always in mind AND tounderstand the difficult challenge of symbolically representing these real states. Thus the chemical reaction shown on this page for the oxidation of octane is both an imperfect representation of the burning of one molecule, and a symbolic representation of the complex activity occurring in the roiling , hot space of an engine cylinder. To understand this section fully, you need to be familiar with the principles of thermochemistry and thermodynamics described in your chemistry text.