The chromium in a series of steel samples was determined by ICP emission spectroscopy. The spectrometer was calibrated with a series of standards containing 0.2.0, 4.0, 6.0, and 8.0 μg K2 Cr2 O2 per milliliter. The instrument readings for these solutions were 3.1, 21.5, 40.9, 57.1, and 77.3. respectively, in arbitrary units.
(a) Plot the data using a spreadsheet.
(b) Find the equation for the regression line.
(c) Calculate standard deviations for the slope and the intercept of the line in (b).
(d) The following data were obtained for replicate 1.00-g samples of cement dissolved in HCI and diluted to 100.0 mL after neutralization.
Calculate the percentage of Cr2O3 in each sample. What are the absolute and relative standard deviations for the average of each determination?