To get this unique rate, choose any one rate and divide it by the stoichiometric coefficient.When the reaction has the formula: \[C_R_1 \dots C_R_n \rightarrow C_P_1 \dots C_P_n\] The general case of the unique average rate of reaction has the form: rate of reaction = \( - \dfrac\dfrac = \dots = - \dfrac\dfrac = \dfrac\dfrac = \dots = \dfrac\dfrac\) Reaction rates have the general form of (change of concentration / change of time). One is called the average rate of reaction, often denoted by (Δ[conc.] / Δt), while the other is referred to as the instantaneous rate of reaction, denoted as either: \[ \lim_ \dfrac \] which is the definition of the derivative \[ \dfrac \] The average rate of reaction, as the name suggests, is an rate, obtained by taking the change in concentration over a time period, for example: -0.3 M / 15 minutes.
However, there are also other factors that can influence the rate of reaction. When you are able to write a rate law equation for a certain reaction, you can determine the Reaction Order based on the values of s and t.
If you were to observe a chemical reaction to occur in two different setting (one at a higher temperature than the other), you would most likely observe the reaction occuring at a higher temperature to have a higher rate.
The concentration of a reactant always decreases with time, so \(\Delta [A]\) and \(\Delta [A]\) are both negative.
Since negative rates do not make much sense, to make the rate come out positive.
Therefore, putting a negative sign in front of the variable will allow for the solution to be a positive rate.
A rate law is an expression which relates that rate of a reaction to the rate constant and the concentrations of the reactants.Now, we will turn our attention to the importance of stoichiometric coefficients.Even though the concentrations of A, B, C and D may all change at different rates, there is only one average rate of reaction.This is because as you increase the temperature, the kinetic energy of the reactants increase, allowing for more collisions between the molecules.This, therefore, allows for products to be formed faster.A rate constant, \(k\), is a proportionality constant for a given reaction.The general rate law is usually expressed as: \[ \text = k[A]^s[B]^t \tag\] As you can see from equation 2 above, the reaction rate is dependent on the concentration of the reactants as well as the rate constant.The products, on the other hand, increase concentration with time, giving a positive number. The overall rate also depends on stoichiometric coefficients; consider the more general balanced equation \(a A b B \rightarrow c C d D\), where the lower case letters represent the coefficients of the balanced equation and the upper case letters (i.e. As with the example above, the rate of reaction can be defined with respect to loss of reactants or gain of products: Since Rate of Disappearance and Rate of Formation are equal \( - \dfrac\dfrac = - \dfrac\dfrac = \dfrac\dfrac = \dfrac\dfrac\) It is worth noting that the process of measuring the concentration can be greatly simplified by taking advantage of the different physical or chemical properties (i.e.: phase difference, reduction potential, etc.) of the reagents or products involved in the reaction by using the above methods.We have emphasized the importance of taking the sign of the reaction into account in order to get a positive reaction rate.Chemical reactions vary greatly in the speed at which they occur.Some are essentially instantaneous, while others may take years to reach equilibrium.