Page 355 - Excel for Scientists and Engineers: Numerical Methods

332 EXCEL: NUMERICAL METHODS

Problems

Data for, and answers to, the following problems are found in the folder "Ch. 14 (Nonlinear
Regression)" in the "Problems & Solutions" folder on the CD.

1. First Order Reaction. The absorbance vs. time data in Table 14-1 was
recorded for a chemical reaction. The reaction was believed to follow a first-
order exponential decay:

Table 14-1. Absorbance vs. time data.
1 t,sec I Aobsd I t,sec I Aobsd
I 0 I 0.002000 I 10 I 0.000077 I
1 0 .OO 1 44 1 11 0.000051
2 0.001 070 12 0.000036
3 0.000739 13 0.000026
I 4 I 0.000542 I 14 I 0.000021 I

5 0.000367 15 0.000014
6 0.000263 16 0.00001 0
I 7 I 0.000200 I 17 I 0.000007 I
I 8 I 0.000140 I 18 I 0.000005 I
I 9 I 0.000100 I I I

Determine the rate constant k using the Solver.

2. Logistic Curve I. The data in Table 14.2 can be described by a simple
logistic curve
1
Y=
1 + e-ax
Determine the constant a using the Solver.