(a) Plot the data.
(b) Obtain a least-squares line for the data.
(c) Calculate standard deviations for the slope and residuals for the line in (b).
(d) The following data were obtained for replicate 1.000-g samples of cement that
were dissolved in HCI and diluted to 100.0 mL after neutralization.
Emission Reading
Blank Sample A Sample B Sample C
Replicate I 5.1 28.6 40.7 73.1
Replicate 2 4.8 28.2 41.2 72.1
Replicate 3 4.9 28.9 40.2 spilled
Calculate the percent Na20 in each sample. What are the absolute and relative
standard deviation for the average of each determination?
9-22 The chromium in an aqueous sample was determined by pi petting 10.0 mL of the unknown
into each of five 50.0-mL volumetric flasks. Various volumes of a standard containing
12.2 ppm Cr were added to the flasks, following which the solutions were diluted
to volume.
(a)
(b)
(c)
(d)
(e)
Unknown, mL
10.0
10.0
10.0
10.0
10.0
Plot the data.
Standard, mL
0.0
10.0
20.0
30.0
40.0
Absorbance
0.201
0.292
0.378
0.467
0.554
Derive an equation for the relationship between absorbance and volume of standard.
Calculate the standard deviation for the slope and the standard deviation about regression
in (b).
Calculate the ppm Cr in the sample.
Calculate the standard deviation of the result in (d) .