Measurements will be imprecise unless we can establish a level playing field for energy measurement. We learned to call these predetermined conditions the standard state . Accurate determinations of energy that can be compared from time to time and place to place depend on measurements recalculated to 25 degrees Celsius, with each of the components in its natural form at that temperature. To develop a standard for chemical comparison, we deal with standard enthalpy changes. The molecular weight of glucose is 180, the oxidation 1g yields about 16kJ of energy, about 4kcal.
Fats yield much higher energy per unit mass than carbohydrates.
We understand this fact as a result of the structure of the fats in comparison to carbohydrates. Copyright 2000, Laurence I. Peterson and Matthew E. Hermes College of Science and Mathematics Kennesaw State University 1000 Chastain Rd.