Question

Discussion: What is the significance of the value n,of the reaction order in chemical kinetics? Derive the integrated law for zero and second order kinetics.

Answer 1

Significance of 'n' in Rate order. The reaction order is the relationship between the concentrations of species and the rate of reaction. According to Rate law; for many reactions Rate а 4 = KCA Св.79 given as The overall order is as a the sum of x and y (This is the experimental value according to Rate law). where CA » concentration of species A x is the order with respect to species A (B] & concentration of species B y is the order wet species B. A is Rate constant 2 n is the reaction chemical reaction . by adding reaction respect to reactants order for whole This can be found orders with I n = x + y main kinetics plot which of the in is simply the determine the reaction. Scanned with CamScanner

'm not necassarily an integer. Zero & indicate that concentration of - that species doesnot affect the Rate Reaction . Negatine : indicate that concentration of species Inversely affects the nate of the Reaction. Positive & indicate that concentration of species directly affects Rate of Reaction. Therefore m desvukes the Reaction tells us how - Reaction ů affected the Reactants. order of the pate by concentration for zero order & Rate of Reaction is I Independent of the concentration [no]. Rate: K [AJO for first aider : Rate of Reaction is directly proportional to the concentration of reactants [n=1] Rate K [A] 2 for second order: Rate of Reaction is proportional to the square of concentration of Reactant, 30 doubling the reactan concentration quad ouples the reaction. Rate [n=2 ] CS Scanned with Ratek Cab CamScanner

Integrated buder xero law for Kinetics. and second for Rate zero order Kinetics is in dependent of the concentration the reactants. Rate Law for zuio order Reaction Rate =k where K is the constant The rate product - t=0 t=t A - a 9 x Consider o rractant changes to product Rate = K CAJ dx = K [ao-x] at dx = k at a-x) = 1 lao-x)° dx = Integrate Kat both sides from limits Oton and o tot 2 kt decomposed to form product as amount Scanned with CamScanner

after tenie t Concentration of Reactant at = aon at = ao-kt a = [A] conen [A ] = after terme t.. -Kt + [a) 1 On comparing ma slope get slope = -K to as y = mate int ucept we intercept = [as] for second order Kinetics product L t=o tzt A + B - ao ao aux qorx Consider a Reaction having react ants of equal concentration initially [a then after time t' [ac ] concentration from ao form producat Rate of Reaction dx = K Ca x)² dx = k dt (ao-x) Integrate both sides Ics Scanned with 0 at CamScanner

lao-x)2 x = K t 0.-). Jo kt (Ao] = Kt tt (А1 / Integrated Rate Law for Sicond order kinetics]. On comp aurig to y = mx to we get slope = k int ucept = 1 of grapth drawn bet ween I and time. CSC Scanned with CamScanner

Graphs Zero oidu Kinetics TA] = - Kt + [aa] Canon slope =-k [ao] concentration Rate = x CAO time Second order, Kinetics slopek HAI tirrie Loncentration) [Ao] rate : k loo-x) y m hati kao-x) (parabolic CS Scanned with CamScanner concentration