89.4 Determination of the reaction order
§9.4 Determination of the reaction order c c0,1 t c0,2 c0,3 r0,1 r0,2 r0,3
89.4 Determination of the reaction order Significance r=k[AjaB]ICY Integration methods Once we determine the order of a reaction we can write out the rate Differential methods equation of the reaction and tell the details of the kinetic characteristics of the methods reaction according to the rate equation Partial order methods Otherwise, the rate equation can provide useful information about the mechanism of the reaction Isolation methods Therefore. determination of the order of the reaction is a work of great importance
r = k [A][B] [C] Once we determine the order of a reaction, we can write out the rate equation of the reaction and tell the details of the kinetic characteristics of the reaction according to the rate equation. Otherwise, the rate equation can provide useful information about the mechanism of the reaction. Therefore, determination of the order of the reaction is a work of great importance. Significance §9.4 Determination of the reaction order methods Integration methods Differential methods Partial order methods Isolation methods
89.4 Determination of the reaction order 9.4.1 differential method The differential methods use the differential rate equation to determine the order of the reaction (1) The attempt method: (Trial and error) C2 ONa+ C2HS(CH3)2SI>Nal+ C2HSOCHs + S(CH3)2 r=k[C2H, ONa]aC2 Hs(CH)2SI] A+B→>Pr=k[A][B] The values of k can be calculated from the selected integrated equation from a knowledge of initial concentration(co)and the concentration at various time intervals(c). If the reaction is of the selected order of reaction, the k at different intervals thus obtained should be the same
(1) The attempt method: The values of k can be calculated from the selected integrated equation from a knowledge of initial concentration (c0 ) and the concentration at various time intervals (c). If the reaction is of the selected order of reaction, the k at different intervals thus obtained should be the same. A + B → P C2H5ONa + C2H5 (CH3 ) 2 SI → NaI + C2H5O C2H5 + S(CH3 ) 2 r = k[C2H5ONa][C2H5 (CH3 ) 2 SI] r = k [A][B] (Trial and error) The differential methods use the differential rate equation to determine the order of the reaction. §9.4 Determination of the reaction order 9.4.1 differential method
89.4 Determination of the reaction order 9.4.1 differential method Table I kinetic data for C2 HSONa+ CHs(CH3)2SI reaction at 337.10 K ts 10[A/ moldm-3 102B]/mol-dm-3 0 9.625 4.920 720 8.578 3.878 1200 8.046 3.342 1800 7485 2.783 2520 6985 2.283 3060 6.709 2.005 3780 6.386 1682 4.704 r=kA]B1B
t/s 102 [A]/ moldm-3 102 [B] / moldm-3 0 9.625 4.920 720 8.578 3.878 1200 8.046 3.342 1800 7.485 2.783 2520 6.985 2.283 3060 6.709 2.005 3780 6.386 1.682 4.704 Table 1 kinetic data for C2H5ONa + C2H5 (CH3 ) 2 SI reaction at 337.10 K r = k [A][B] §9.4 Determination of the reaction order 9.4.1 differential method
89.4 Determination of the reaction order 9.4.1 differential method Table2 k of the reaction of different order CF1 0 =2 0 a=1 B B=1 0 2 B=1 104 104 103 103 0 1.454 1.599 3.313 1764 7.579 3.642 720 1.108 1.143 3.088 1.604 7.357 3.678 1200 0.935 1.205 3.051 1.550 10.02 3.760 1800 1.042 0.960 2.751 1.333 10.93 3.773 2520 0.511 0.747 2.405 1.093 11.11 3.731 3060 0.449 0.685 2.440 1.042 13.32 3.729 Therefore, the rate equation is: r=KICH ONallC2Hs(CH3)2sI
=0 =1 =0 =2 =0 =1 =0 =0 =1 =0 =2 =1 105 104 104 103 103 103 0 1.454 1.599 3.313 1.764 7.579 3.642 720 1.108 1.143 3.088 1.604 7.357 3.678 1200 0.935 1.205 3.051 1.550 10.02 3.760 1800 1.042 0.960 2.751 1.333 10.93 3.773 2520 0.511 0.747 2.405 1.093 11.11 3.731 3060 0.449 0.685 2.440 1.042 13.32 3.729 Table2 k of the reaction of different order r = k[C2H5ONa][C2H5 (CH3 ) 2 Therefore, the rate equation is: SI] k t , =1 =1 103 3.642 3.678 3.760 3.773 3.731 3.729 §9.4 Determination of the reaction order 9.4.1 differential method