Method of Initial Rates
The order of a reaction for each reactant can be estimated from the variation in initial rate with the concentration of that reactant, using the natural logarithm of the typical rate equation
For example the initial rate can be measured in a series of experiments at different initial concentrations of reactant A with all other concentrations, ... kept constant, so that
The slope of a graph of as a function of then corresponds to the order x with respect to reactant A.
However this method is not always reliable because
- measurement of the initial rate requires accurate determination of small changes in concentration in short times (compared to the reaction half-life) and is sensitive to errors, and
- the rate equation will not be completely determined if the rate also depends on substances not present at the beginning of the reaction, such as intermediates or products.
The tentative rate equation determined by this method is therefore normally verified by comparing the concentrations measured over a longer time (several half-lives) with the integrated form of the rate equation.
Read more about this topic: Order Of Reaction
Famous quotes containing the words method of, method, initial and/or rates:
“Frankly, I adore your catchy slogan, “Adoption, not Abortion,” although no one has been able to figure out, even with expert counseling, how to use adoption as a method of birth control, or at what time of the month it is most effective.”
—Barbara Ehrenreich (b. 1941)
“If all feeling for grace and beauty were not extinguished in the mass of mankind at the actual moment, such a method of locomotion as cycling could never have found acceptance; no man or woman with the slightest aesthetic sense could assume the ludicrous position necessary for it.”
—Ouida [Marie Louise De La Ramée] (1839–1908)
“For those parents from lower-class and minority communities ... [who] have had minimal experience in negotiating dominant, external institutions or have had negative and hostile contact with social service agencies, their initial approaches to the school are often overwhelming and difficult. Not only does the school feel like an alien environment with incomprehensible norms and structures, but the families often do not feel entitled to make demands or force disagreements.”
—Sara Lawrence Lightfoot (20th century)
“In the U.S. for instance, the value of a homemaker’s productive work has been imputed mostly when she was maimed or killed and insurance companies and/or the courts had to calculate the amount to pay her family in damages. Even at that, the rates were mostly pink collar and the big number was attributed to the husband’s pain and suffering.”
—Gloria Steinem (20th century)