Question

4-35 Here are mass spectrometric signals for methane in Hy: CH 4 (vol%): 0.062 0.122 0.245 0.486 0.971 47.5 1.921 Signal (mV): 9.1 95.6 193.8 387.5 812.5 1671.9 (a) Subtract the blank value (9.1) from all other values. Then use the method of least squares to find the slope and intercept and their uncertainties. Construct a calibration curve. (b) Replicate measurements of an unknown gave 152.1. 154.9, 153.9, and 155.1 mV, and a blank gave 8.2, 9.4, 10.6, and 7.8 mV. Subtract the average blank from the average unknown to find the average corrected signal for the unknown. (c) Find the concentration of the unknown, its standard uncertainty (ur), and the 95% confidence interval. (d) Add the unknown data point with its error bars (u) to the calibration curve.

Answer 1