1 INTRODUCTION TO ORIGIN 8.0 DATA ANALYSIS AND PLOTTING SOFTWARE (UPDATED 08/2011) Origin (Originlab Corporation, Inc., One Roundhouse Plaza, Northhampton, MA 01060) is one of several software packages designed specifically for plotting and analyzing quantitative data. You will be using Origin for a variety of applications in this course. The purpose of this document is to introduce you to two of the primary capabilities of ORIGIN software, namely plotting and curve-fitting capabilities, and to illustrate applications of Origin in conjunction with spread-sheet programs such as Microsoft EXCEL. Data for the spectrophotometric determination of ferrous iron (Table 1, Columns A –E) and masses of paper clips (Table 1, Columns F and G) are used to illustrate applications of the Origin software to both linear and nonlinear data sets. Data in the first three columns represent experimentally determined values of absorbance and percent transmittance for different Fe(II) concentrations treated with 1,10-phenanthroline under appropriate conditions. Data in the fourth column represent realistic absorbance errors for a spectrophotometer good to ± 0.2 %T. Data in the fifth column are exaggerated (x 10) transmittance errors; exaggerated values are used to aid in visualization. The data are to be entered into columns A(X) and B(Y) through E(Y) of an Origin worksheet using procedures described below. Origin will be used to plot the data and to fit suitable models to the plotted data. The figure at the end of this presentation illustrates a formatted plot of absorbance vs. concentration with a least-squares line included. Table 1. Numerical data used to illustrate basic applications of data analysis and plotting software. Concn. (10-4 mol/L) A (au)a T (%) Error (au) Error (%T) Mass (g) Number of values A(X) B(Y) C(Y) D(Y) E(Y) F G 0 0.000 100 0.00087 2 0.4621 1 0.0226 0.0438 90.5 0.00095 2 0.4632 7 0.0458 0.0615 86.8 0.001 2 0.4644 17 0.0915 0.1238 75.2 0.0011 2 0.4655 16 0.229 0.292 51 0.0017 2 0.4667 9 0.458 0.595 25.4 0.0034 2 0.4679 1 0.915 1.167 6.8 0.013 2 1.84 2.22 0.6 0.12 2 2.5 3.01 0.1 0.48 2 aAlthough absorbance is a unitless quantity, it will be helpful to imply units, au, in expressions involving absorbance. Notes: 1. Throughout this discussion,“click” means a single click with the left mouse button; “double click” means two quick clicks with the left mouse button and right click means one click with the right mouse button. 2. One of the figures you are to produce is included at the end of this tutorial. A series of sequential selections from one or more sequential menus will be represented in italics as “Step1/Step2/Step3”, etc. in which the slash marks are separators and are not entered from the keyboard. For example, to open Origin click on “start/course software/science/chm/originpro 8”. User-added text, numbers, etc. are represented by boldtype.
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