PRACTICAL ASPECTS OF THE ANALYSIS OF THE PROGRESSION CURVES OF FIRST AND PSEUDO-FIRST ORDER REACTIONS

Nackiewicz, Joanna; Hurek, Józef; Wróbel, Aneta

doi:10.21577/0100-4042.20170447

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Educação • Quím. Nova 43 (1) • Jan 2020 • https://doi.org/10.21577/0100-4042.20170447 linkcopy

PRACTICAL ASPECTS OF THE ANALYSIS OF THE PROGRESSION CURVES OF FIRST AND PSEUDO-FIRST ORDER REACTIONS

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The paper presents a simple method of determining iteratively the progression curve asymptote for first and pseudo-first order reactions. For selected student exercises, thus obtained results were compared (see Supplementary Material) with those found by means of the method of determining asymptotes experimentally. A nonlinear fitting method was additionally employed to assess the accuracy.

Keywords:
second-year undergraduate; physical chemistry; kinetics; chemoinformatics; mechanisms of reactions

Data range			Results obtained using experimental asymptote					Results obtained using calculated asymptote
t.s	points	β	Y_{∞_exp}	n	k [1/s]	SD	R²_max	Y_{∞_calc}	n	k [1/s]	SD	R²_max
1500	51	1	0.911356	1	0.00416	1.25E-05	1	0.911	1	0.00411	1.30E-05	1
540	19	0.89	0.911356	1	0.00432	2.86E-05	0.999	0.938	1	0.0046	2.06E-05	0.9997
390	14	0.81	0.911356	1	0.00442	3.70E-05	0.999	0.933	1	0.00461	3.73E-05	0.9992
300	11	0.71	0.911356	0.9 - 1	0.00446	5.82E-05	0.998	0.893	1	0.00436	5.66E-05	0.9984
210	8	0.58	0.911356	0.7-0.8	0.00445	1.12E-04	0.996	0.513	1	0.0032	6.82E-05	0.9972
180	7	0.52	0.911356	0.5	0.00441	1.48E-04	0.994	-0.212	1	0.00218	5.46E-05	0.997
120	6	0.36	0.911356	0
90	4	0.27	0.911356	0

Data range			Results obtained using experimental asymptote					Results obtained using calculated asymptote
t.s	points	β	Y_{∞_exp}	n	k [1/s]	SD	R²_max	Y_{∞_calc}	n	k [1/s]	SD	R²_max
705	48	1	0.83825	1	0.00778	2.79E-05	0.9994	0.839	1	0.00792	2.69E-05	0.9995
285	20	0.9	0.83825	1	0.00815	3.58E-05	0.9996	0.853	1	0.00846	2.89E-05	0.9998
210	15	0.81	0.83825	1	0.00828	3.30E-05	0.99987	0.871	1	0.00877	8.82E-06	0.9999
150	11	0.7	0.83825	1	0.008396	2.35E-05	0.9999	0.868	1	0.00873	1.35E-05	0.9999
105	8	0.57	0.83825	1	0.008468	2.70E-05	0.99994	0.865	1	0.00871	2.45E-05	0.9999
90	9	0.51	0.83825	1	0.008481	3.47E-05	0.99991	0.872	1	0.00871	3.28E-05	0.9999
60	5	0.37	0.83825	0.9	0.00854	5.31E-05	0.99998	0.65	1	0.00736	1.22E-05	1
45	4	0.28	0.83825	0.8	0.00847	6.24E-05	0.99989	0.568	1	0.00698	1.29E-05	1

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Sociedade Brasileira de Química Instituto de Química, Universidade Estadual de Campinas (Unicamp), CP6154, 13083-0970 - Campinas - SP - Brazil
E-mail: quimicanova@sbq.org.br

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[TFN1] where: n - determined reaction order (on the basis of the maximum R² value); β - the maximum range of analysis of progression curve data (conversion);

k - observed pseudo-first order reaction rate constant; SD - standard deviation from the reaction rate constant value; Italics- the range where the analysis breaks down. The values of reaction rate constant and deviations were calculated in each case using equation (4).