enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Energy profile (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Energy_profile_(chemistry)

    The height of energy barrier is always measured relative to the energy of the reactant or starting material. Different possibilities have been shown in figure 6. Figure 6:Reaction Coordinate Diagrams showing reactions with 0, 1 and 2 intermediates: The double-headed arrow shows the first, second and third step in each reaction coordinate diagram.

  3. Exothermic reaction - Wikipedia

    en.wikipedia.org/wiki/Exothermic_reaction

    An energy profile of an exothermic reaction. In an exothermic reaction, by definition, the enthalpy change has a negative value: ΔH = H products - H reactants < 0. where a larger value (the higher energy of the reactants) is subtracted from a smaller value (the lower energy of the products). For example, when hydrogen burns: 2H 2 (g) + O 2 (g ...

  4. Hammond's postulate - Wikipedia

    en.wikipedia.org/wiki/Hammond's_postulate

    This can be explained with reference to potential energy diagrams: Energy diagrams showing how to interpret Hammond's Postulate. In case (a), which is an exothermic reaction, the energy of the transition state is closer in energy to that of the reactant than that of the intermediate or the product.

  5. Exothermic process - Wikipedia

    en.wikipedia.org/wiki/Exothermic_process

    In an adiabatic system (i.e. a system that does not exchange heat with the surroundings), an otherwise exothermic process results in an increase in temperature of the system. [11] In exothermic chemical reactions, the heat that is released by the reaction takes the form of electromagnetic energy or kinetic energy of molecules. [12]

  6. Activation energy - Wikipedia

    en.wikipedia.org/wiki/Activation_energy

    Example of an enzyme-catalysed exothermic reaction The relationship between activation energy and enthalpy of reaction (ΔH) with and without a catalyst, plotted against the reaction coordinate. The highest energy position (peak position) represents the transition state.

  7. Activated complex - Wikipedia

    en.wikipedia.org/wiki/Activated_complex

    The energy serves as a threshold that reactant molecules must surpass to overcome the energy barrier and transition into the activated complex. Endothermic reactions absorb energy from the surroundings, while exothermic reactions release energy. Some reactions occur spontaneously, while others necessitate an external energy input.

  8. Enzyme catalysis - Wikipedia

    en.wikipedia.org/wiki/Enzyme_catalysis

    Enzymes utilizing such cofactors include the PLP-dependent enzyme aspartate transaminase and the TPP-dependent enzyme pyruvate dehydrogenase. [ 21 ] [ 22 ] Rather than lowering the activation energy for a reaction pathway, covalent catalysis provides an alternative pathway for the reaction (via to the covalent intermediate) and so is distinct ...

  9. Thermochemical equation - Wikipedia

    en.wikipedia.org/wiki/Thermochemical_equation

    In thermochemistry, a thermochemical equation is a balanced chemical equation that represents the energy changes from a system to its surroundings. One such equation involves the enthalpy change, which is denoted with Δ H {\displaystyle \Delta H} In variable form, a thermochemical equation would appear similar to the following: