Order Of Reaction

1. Order Of Reaction

2. Drug stability The term drug stability refers to the extent to which a drug substance or product retains, within specified limits and throughout its period of storage and use, the same properties and characteristics that it possessed at the time of its manufacture.

3. ACCELERATED STABILITY TESTING Shelf life: t90 : Time required to reduce the concentration to 90% of its initial concentration. t90 = 0.105/K Stability of formulation can be determined by shelf life.

4. ACCELERATED STABILITY TESTING Shelf life Determination

5. TEMPERATURE ZONES

6. TEMPERATURE ZONES

7. STORAGE CONDITION STABILITY STUDY

8. Order of reaction The Order of reaction refers to the relationship between the rate of a chemical reaction and the concentration of the species taking part in it. In order to obtain the reaction order, the rate expression (or the rate equation) of the reaction in question must be obtained.

9. Order of reaction

10. Order of reaction

11. Order of reaction

12. Order of reaction Once the rate equation is obtained, the entire composition of the mixture of all the species in the reaction can be understood.

13. Zero Order Reactions The rate of reaction is independent of the concentration of the reactants in these reactions. A change in the concentration of the reactants has no effect on the speed of the reaction Examples of these types of reactions include the enzyme-catalyzed oxidation of CH3CH2OH (ethanol) to CH3CHO (acetaldehyde).

14. First-Order Reactions The rates of these reactions depend on the concentration of only one reactant, i.e. the order of reaction is 1. In these reactions, there may be multiple reactants present, but only one reactant will be of first-order concentration while the rest of the reactants would be of zero-order concentration. Example of a first-order reaction: 2H2O2 → 2H2O + O2

15. Pseudo-First Order Reactions In a pseudo-first order reaction, the concentration of one reactant remains constant and is therefore included in the rate constant in the rate expression. The concentration of the reactant may be constant because it is present in excess when compared to the concentration of other reactants, or because it is a catalyst. Example of a pseudo-first order reaction: CH3COOCH3 + H2O → CH3COOH + CH3OH (this reaction follows pseudo-first order kinetics because water is present in excess).

16. Second-Order Reaction When the order of a reaction is 2, the reaction is said to be a second-order reaction. The rate of these reactions can be obtained either from the concentration of one reactant squared or from the concentration of two separate reactants. The rate equation can correspond to r = k[A]2 or r = k[A][B] Example of a second-order reaction: NO2 + CO → NO + CO2

17. Difference Between Molecularity and Order of Reaction

18. Second-Order Reaction When the order of a reaction is 2, the reaction is said to be a second-order reaction. The rate of these reactions can be obtained either from the concentration of one reactant squared or from the concentration of two separate reactants. The rate equation can correspond to r = k[A]2 or r = k[A][B] Example of a second-order reaction: NO2 + CO → NO + CO2

19. How to Determine Reaction Order Initial Rates Method Integral Method Differential Method

20. Initial Rates Method The method of initial rates allows the values of these reaction orders to be found by running the reaction multiple times under controlled conditions and measuring the rate of the reaction in each case. All variables are held constant from one run to the next, except for the concentration of one reactant

21. Initial Rates Method First, the natural logarithm form of the power-law expression is obtained. It is given by: ln r = ln k + x.ln[A] + y.ln[B] + …. The partial order corresponding to each reactant is now calculated by conducting the reaction with varying concentrations of the reactant in question and the concentration of the other reactants kept constant.

22. Initial Rates Method If the partial order of A is being determined, the power-law expression of the rate equation now becomes ln r = x. ln [A] + C, where C is a constant. A graph is now plotted by taking ‘ln r’ as a function of ln[A], the corresponding slope is the partial order, given by x.

23. Integral Method The order of reaction obtained from the initial rates method is usually verified using this method. The measured concentrations of the reactants are compared with the integral form of the rate law. For example, the rate law for a first-order reaction is verified if the value for ln[A] corresponds to a linear function of time (integrated rate equation of a first-order reaction: ln[A] = -kt + ln[A]0).

24. Integral Method Either the differential rate law or the integrated rate law can be used to determine the reaction order from experimental data. Often, the exponents in the rate law are the positive integers: 1 and 2 or even 0. Thus the reactions are zeroth, first, or second order in each reactant

25. Integral Method

26. Differential Method The order of reaction obtained from the initial rates method is usually verified using this method. The measured concentrations of the reactants are compared with the integral form of the rate law. For example, the rate law for a first-order reaction is verified if the value for ln[A] corresponds to a linear function of time (integrated rate equation of a first-order reaction: ln[A] = -kt + ln[A]0).

27. Differential Method