Gesamtreaktionsrate

The **Gesamtreaktionsrate** (German for "total reaction rate") refers to the overall rate at which a chemical reaction proceeds under given conditions. It quantifies how quickly reactants are converted into products in a specified time frame and is a fundamental concept in chemical kinetics. The rate depends on factors such as concentration of reactants, temperature, catalysts, and reaction mechanisms.

In homogeneous reactions, the overall reaction rate is typically expressed as the change in concentration of a reactant or product per unit time, often denoted as *r* or *v*. For a general reaction *aA + bB → cC + dD*, the rate can be written as:

r = −(1/a) d[A]/dt = −(1/b) d[B]/dt = (1/c) d[C]/dt = (1/d) d[D]/dt

The negative sign indicates that reactants are consumed, while products accumulate. The rate law for a reaction describes how the rate depends on reactant concentrations, often derived experimentally. For an elementary reaction, the rate law directly reflects the stoichiometry, but for complex reactions, it must be determined empirically.

Temperature plays a critical role in determining the overall reaction rate, as described by the Arrhenius equation:

k = A e^(−Ea/RT)

where *k* is the rate constant, *A* is the pre-exponential factor, *Ea* is the activation energy, *R* is the gas constant, and *T* is the temperature in Kelvin. Increasing temperature generally increases the rate by providing more energy to reactant molecules, allowing them to overcome the activation barrier.

Catalysts can also significantly alter the overall reaction rate by providing an alternative reaction pathway with a lower activation energy, thereby increasing the rate constant without being consumed in the process. Understanding the overall reaction rate is essential for optimizing reaction conditions in industrial processes, such as maximizing yield or minimizing waste.