Resumen de Measuring the gas constant R: propagation of uncertainty and statistics
Robert J. Olsen, Simeen Sattar
Determining the gas constant R by measuring the properties of hydrogen gas collected in a gas buret is well suited for comparing two approaches to uncertainty analysis using a single data set. The brevity of the experiment permits multiple determinations, allowing for statistical evaluation of the standard uncertainty uR within a laboratory period, while calculating R from the several measured quantities (pressure, volume, etc.) invokes a number of different methods of estimating the individual uncertainties involved in the calculation of the combined standard uncertainty uc(R). The two uncertainties, as obtained by several classes of upper-level college students, are typically within a factor of two or three. In the course of the data analysis, students interpret a q-q plot, identify outliers using Dixon's test, and apply the F test to the ratio of the two variances. Thus, the experiment gives students experience with a variety of methods for evaluating data they have gathered themselves. The Supporting Information contains an Excel workbook containing student data and all the above-mentioned calculations.
