Answer:
In chemical kinetics, the rate constant (k) is a proportionality constant that relates the rate of a chemical reaction to the concentrations of the reactants. It is often included in the rate law equation, which expresses the relationship between the rate of the reaction and the concentrations of the reactants.
However, the rate constant is not truly constant because it can vary with different experimental conditions. The rate constant is affected by factors such as temperature, pressure, and the presence of catalysts or inhibitors. For example, an increase in temperature usually leads to an increase in the rate constant, while the addition of a catalyst can decrease the activation energy and increase the rate constant.
Two specific examples that support this statement are:
1) The effect of temperature on the rate constant: Consider the reaction A → B, which has a rate law equation of rate = k[A]. If the temperature is increased, the rate constant will increase due to the increase in kinetic energy of the reactant molecules. This means that the reaction will proceed faster at higher temperatures, even if the concentration of A remains the same.
2) The effect of catalysts on the rate constant: Consider the reaction C + D → E, which has a rate law equation of rate = k[C][D]. If a catalyst is added to the reaction, it can increase the rate constant by providing an alternate pathway with a lower activation energy. This means that the reaction will proceed faster at the same concentrations of C and D with the catalyst present than without it.
Step-by-step explanation: