OpenStax Chemistry 2e The 1995 Nobel Prize in Chemistry was shared by Paul J. Crutzen, Mario J. Molina, and F. Sherwood Rowland “for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone.” Molina, a Mexican citizen, carried out the majority of his work at the Massachusetts Institute of Technology (MIT). (a) … Continue reading Portrait of a Chemist: Mario J. Molina – Formation and Decomposition of Ozone

Lee. D. Simon Coloured transmission electron micrograph (TEM) of T2 bacteriophage viruses (orange) attacking an Escherichia coli bacterium. Each phage consists of a large DNA-containing head and a tail composed of a central sheath with several fibres. The fibres attach to the host cell surface, and the phage DNA is injected into the cell through … Continue reading Image: T2 Bacteriophages Attacking E. coli [Colorized TEM] by Lee D. Simon

OpenStax Chemistry 2e A homogeneous catalyst is present in the same phase as the reactants . It interacts with a reactant to form an intermediate substance , which then decomposes or reacts with another reactant in one or more steps to regenerate the original catalyst and form product. As an important illustration of homogeneous catalysis, … Continue reading Homogeneous Catalysts

OpenStax Chemistry 2e Among the factors affecting chemical reaction rates was the presence of a catalyst , a substance that can increase the reaction rate without being consumed in the reaction. The concepts introduced on reaction mechanisms provide the basis for understanding how catalysts are able to accomplish this very important function. The picture below … Continue reading Catalysis

OpenStax Chemistry 2e It’s often the case that one step in a multistep reaction mechanism is significantly slower than the others. Because a reaction cannot proceed faster than its slowest step, this step will limit the rate at which the overall reaction occurs. The slowest step is therefore called the rate-limiting step (or rate-determining step) … Continue reading Relating Reaction Mechanisms to Rate Laws

Photo by Pixabay on Pexels.com OpenStax Chemistry 2e An elementary termolecular reaction involves the simultaneous collision of three atoms, molecules, or ions. Termolecular elementary reactions are uncommon because the probability of three particles colliding simultaneously is less than one one-thousandth of the probability of two particles colliding. There are, however, a few established termolecular elementary … Continue reading Termolecular Elementary Reactions

Photo by Pixabay on Pexels.com OpenStax Chemistry 2e A bimolecular reaction involves two reactant species, for example: A + B ⟶ productsand2A ⟶ products For the first type, in which the two reactant molecules are different, the rate law is first order in A and first order in B (second-order overall): rate = k[A][B] For … Continue reading Bimolecular Elementary Reactions

OpenStax Chemistry 2e The molecularity of an elementary reaction is the number of reactant species (atoms, molecules, or ions). For example, a unimolecular reaction involves the reaction of a single reactant species to produce one or more molecules of product: A ⟶ products The rate law for a unimolecular reaction is first order: rate = … Continue reading Unimolecular Elementary Reactions

Photo by Chokniti Khongchum on Pexels.com OpenStax Chemistry 2e Chemical reactions very often occur in a step-wise fashion, involving two or more distinct reactions taking place in sequence. A balanced equation indicates what is reacting and what is produced, but it reveals no details about how the reaction actually takes place. The reaction mechanism or … Continue reading Reaction Mechanism

OpenStax Chemistry 2e The minimum energy necessary to form a product during a collision between reactants is called the activation energy (Ea). How this energy compares to the kinetic energy provided by colliding reactant molecules is a primary factor affecting the rate of a chemical reaction. If the activation energy is much larger than the … Continue reading Activation Energy and the Arrhenius Equation