The study of thermodynamics can lead to predicting how chemical reactions will proceed or how much energy is required or released during the reactions. To better understand chemical reactions, a new thermodynamic value called “enthalpy” is introduced. Students will examine the practical applications of bond enthalpies, calorimetry, and other measurements of the energy in chemical reactions. They will also see how the understanding of thermodynamics and enthalpy is helping scientists optimize the use of crop waste for biofuels and build more efficient automobile engines. Part of Chemistry: Challenges and Solutions Series.