The following results were obtained for the determination of calcium in a NIST limestone sample: %CaO = 50.33, 50.22, 50.36, 50.21, and 50.44. Five gross samples were then obtained for a carload of limestone. The average %CaO values for the gross samples were found to be 49.53, 50.12, 49.60, 49.87, and 50.49. Calculate the relative standard deviation associated with the sampling step

The following results were obtained for the determination of calcium in a NIST limestone sample: %CaO = 50.33, 50.22, 50.36, 50.21, and 50.44. Five gross samples were then obtained for a carload of limestone. The average %CaO values for the gross samples were found to be 49.53, 50.12, 49.60, 49.87, and 50.49. Calculate the relative standard deviation associated with the sampling step

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter8: Sampling, Standardization, And Calibration

Section: Chapter Questions

Problem 8.5QAP

See similar textbooks

Similar questions

The ratio of the number of atoms of the isotopes 69Ga and 71Ga in eight samples from different sources was measured in an effort to understand differences in reported values of the atomic mass of gallium: Sample 69Ga/71Ga Sample 69Ga/71Ga1 1.526 60 5 1.528 942 1.529 74 6 1.528 043 1.525 92 7 1.526 854 1.527 31 8 1.527 93 Find the (a) mean, (b) standard deviation, (c) variance, and (d) stan-dard deviation of the mean. (e) Write the mean and standard deviation together with an appropriate number of significant digits
A titrimetric method for the determination of calcium in limestone was tested by analysis of an NIST limestone containing 30.15% CaO. The mean result of four analyses was 30.26% CaO, with a standard deviation of 0.085%. By pooling data from several analyses, it was established that s   = 0.094% CaO.a. Do the data indicate the presence of a systematic error at the 95% confidence level?b. Do the data indicate the presence of systematic error at the 95% confidence level if no pooled value for s was available?
In the determination of ethanol concentration in alcoholic beverages using the GCFID method, why do we need to calculate the coefficient variation (CV). standard deviation, repeatability, response factor and response ratio? And how to calculate this parameter?
The same chloride analysis but using a new method for which the standard deviation was not known, gave the following replicate results, mean and estimated standard deviation: Chloride (ppm) = 346, 359, 350; Mean = 351.67 ppm; Standard deviation = 6.66ppm. Solve for the CI for the 3 determinations at 95% probability level.
1 mL was taken from the sample filtrate and mixed with 13 mL pure water and 4 mL sulfomolybdic acid and 2 mL dilute SnCI2 solution by adding it, and after waiting for 15 minutes, the absorbance of the resulting solutions against pure water was read at 520 nm. if the function of the calibration graph obtained with standard phosphorus solutions of 0.5-2.5 mg/mL is y= 0.245x + 0.107 and the absorbance of the serum sample is 0.342, how many grams of phosphorus is the amount in the sample?
A volume of 250 ml of a 0.05 M solution of a reagent of formula weight (relative molecular mass) 40 was made up, the weighing being done by difference. The standard deviation of each weighing was 0.0001 g. 1 (a) What were the standard deviation and relative standard deviation of the weight of reagent used?
One method for the quantitative determination of the concentration of constituents in a sample analyzed by gas chromatography is area normalization. Here, complete elution of all the sample constituents is necessary. The area of each peak is then measured and corrected for differences in detector response to the different eluates. This correction involves dividing the area by an empirically determined correction factor. The concentration of the analyte is found from the ratio of its corrected area to the total corrected area of all peaks. For a chromatogram containing three peaks, the relative areas were found to be 16.4, 45.2 and 30.2, in order of increasing retention time. Calculate the percentage of each compound if the relative detector responses were 0.60, 0.78 and 0.88, respectively.
A method for the analysis of Ca2+ in water suffers from an interference in the presence of Zn2+. When the concentration of Ca2+ is 100 times greater than that of Zn2+, an analysis for Ca2+ gives a relative error of +0.5%. What is the selectivity coefficient for this method?
Find the standard deviation (if the mass of KHP in three experimental solutions are 0.467,0.48, and 0.48 and the volume of NaOH IN THE exp are 22,29,24 respectively in order to the masses of KHP ) the average molarity of NaOH in each experiment = 5.30x 10^-4 + 4.137x10^-4 + 5.0x10^-4 divided by 3 = 4.81x10^-4 ).
A standard solution was prepared containing 10.0 ppm of an analyte and 15.0 ppm of an internal standard. Analysis of the sample gave signals for the analyte and internal standard of 0.155 and 0.233 (arbitrary units), respectively. Sufficient internal standard was added to an unknown sample to make it 15.0 ppm in the internal standard. Analysis of the unknown sample yielded signals for the analyte and internal standard of 0.274 and 0.198, respectively. Calculate the concentration of analyte in the unknown sample.
A solution is prepared by weighing 5.0000 g of cesium iodide into a 100-mL volumetric flask. The balance used has a precision of 0.2 mg reported as a standard deviation, and the volumetric flask could be filled with a precision of 0.15mL also reported as a standard deviation. What is the estimated standard deviation of concentration (g/mL)?
Pesticide residues were found in a lot of oranges; the compound identified was the epoxide of heptachlor (EH). To quantify the amount of this pesticide in oranges, 20 grams were taken from fruit peels and mixed with methylene chloride to extract it. The concentration of heptachlor epoxide in the sample was determined by gas chromatography coupled to a detector mass (GC-MS); and calibration was performed using anthracene (A) as internal standard. For In this analysis, the anthracene had a concentration of 350 ppm and the same volume was added to each standard. The table below shows the concentrations of the standard and the ratio of the areas.and the sample is: 0.1080.Determine the concentration of heptachlor epoxide in the sample.