SECOND ORDER OF REACTION that is under chemistry.pptx

About the second order of reaction.

1. SECOND ORDER OF REACTION

2. SECOND ORDER REACTION Second order reactions can be defined as chemical reactions wherein sum of the exponents in the corresponding rate law of the chemical reaction is equal to two. the rate of of such reaction can be written either as: r=[A] 2 or as r=[A][B]

3. SECOND ORDER REACTION From the rate law equations given, it can be understood that second order reactions are chemical reactions which depend on either the concentrations of two first-order reactants or the concentration of one-second order reactants. r=[A] x [B] y Where the sum of x and y (which corresponds to the order of the chemical reaction in question) equals two.

4. THINGS TO REMEMBER IN A SECOND ORDER OF REACTIONS Second reaction occurs when two reactant molecules collide with sufficient energy and power orientation. The higher the probability of these collisions, the faster the rate, and therefore, the shorter the half-life. The lower the initial concentration, the lower the probation of the collisions and thus, the longer the half-life.

5. THE UNITS IN THEIR MEANINGS “rate” represents the rate of reaction, which is the change in concentration of a reactant or product per unit time. mol (L * s) “k” is the rate constant which has the unit M -1 s -1 or L*mol -1 s “[A]” and “[B]” represent the concentrations or reactants have units of concentration, typically expressed as mol or M L

6. DIFFERENTIAL AND INTEGRAL To describe how the rate of a second-order reaction changes with concentration of reactants or products, the differential (derivative) rate equation is used as well as the integrated rate equation. The differential rate law can show us how the rate of the reaction changes in time, while the integrated rate equation shows how the concentration of species changes over time.

7. INTEGRATED RATE LAW EXAMPLE The reaction of butadiene gas (C 8 H 12 gas is described by the equation: 2C 4 H 6(g) C 8 H 6(g) This dimerazation reaction is second order with a rate constant equal to 5.76 10 -2 L mol -1 min -1 under certain conditions. If the initial concentration of butadiene is 0.200M, what is the concentration after 10.0 min?

8. EXAMPLE (TRY TO ANSWER THIS) The rate constant for a particular 2nd order of reaction is 0.47M -1 s -1 . if the initial concentration of the reactant is 0.25 mol/L, how long will it take (in seconds) for the concentraion to decrease to 0.13 mol/L?

9. HALF-LIFE OF SECOND ORDER REACTIONS The half-life of a second chemical reaction is the time taken for half of the initial amount of reactant to undergo the reaction. the required equation for half life of second order reactions can be written as follows: t 1/2 = 1 k[A] This equation for the half-life implies that the half life is inversely proportional to the concentration of the reactants.

10. Sample Problem If the only reactant is the initial concentration of A, and it is equivalent to [A]=4.50 10 -5 M and the reaction is a second order with a rate constant k=0.89M -1 s -1 . What is the half-life of this reaction?

11. SAMPLE PROBLEM Ammonium nitrate, a popular ingredient in plant fertilizer, dec

12. DIFFERENCES BETWEEN ZERO, FIRST, AND SECOND ORDER OF REACTIONS

13. First order reactions have a rate proportional to the concentration of one reactant. Second order reactions have a rate proportional to the concentration of two reactants. Zero order reactions have a constant rate independent of reactant concentration.

14. Zero Order Reactions have a constant rule that is independent of the concentration of reactants. this means that the rate of the reaction does not change as the concentration of the reactant changes. Examples of Zero Order Reactions include the breakdown of aspirin and the oxidation of ethanol.

15. First Order Reactions ivolve the decay of a single reactant, and their rate is proportional to the concentration of that reactant. This means that as the concentration of the reactant decreases, so does the rate of the reaction. Examples of First Order Reactions include radioactive decay and the breakdown of hydrogen peroxide.

16. Second Order Reactions involve the collision of two reactants, and their rate is proportional to the concentration of both reactants. This means that as the concentration of either reactant decreases, the rate of decreases. Examples of Second order reactions include the reaction between hydrogen and iodine, and the reaction between nitric oxide and oxygen.