reaktionshastighet

Reaktionshastighet, or reaction rate, is the speed at which a chemical reaction proceeds. It is commonly defined as the change in concentration of a reactant or product per unit time. For a general reaction aA + bB -> cC + dD, the rate can be written as -1/a d[A]/dt = -1/b d[B]/dt = 1/c d[C]/dt = 1/d d[D]/dt. The instantaneous rate is the derivative at a given time, and rates are typically expressed in units of mol L^-1 s^-1.

Rate laws describe how the rate depends on concentrations: rate = k [A]^m [B]^n, where m and n are the reaction orders with respect to A and B, and k is the rate constant. The overall order is m+n. Orders are determined experimentally and may differ from stoichiometric coefficients. First-order reactions depend linearly on one reactant; second-order reactions may depend on the square of one reactant or on the product of two first-order reactants.

Factors influencing Reaktionshastighet include temperature (described by the Arrhenius equation k = A exp(-Ea/RT)), catalysts, concentration, surface area, solvent, and inhibitors. A catalyst provides an alternative pathway with lower activation energy, increasing the rate without changing the reaction’s thermodynamic balance.

Measurement and applications: rates are determined by monitoring concentration changes via spectroscopy, titration, or gas evolution. Understanding Reaktionshastighet is essential for reactor design, process optimization, and the interpretation of reaction mechanisms, including rate-determining steps and, for simple cases, expressions for half-life.

---