Question: Using a method for the determination of % CaO in limestone the following results were obtained for a NIST Certified Reference Sample (CRM): % Cao 50.38, 50.20, 50.31, 50.22 50.41 Five samples were obtained from a railcar of limestone. The analysis of the samples gave the following results: % Cao 55.01, 59.61, 58.82, 64.39, 62.49 a) Determine the variance due to sampling. b) If the samples taken from the railcar had a mass of 0.500 g, what mass

Question: Using a method for the determination of % CaO in limestone the following results were obtained for a NIST Certified Reference Sample (CRM): % Cao 50.38, 50.20, 50.31, 50.22 50.41 Five samples were obtained from a railcar of limestone. The analysis of the samples gave the following results: % Cao 55.01, 59.61, 58.82, 64.39, 62.49 a) Determine the variance due to sampling. b) If the samples taken from the railcar had a mass of 0.500 g, what mass

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter11: Atomic Mass Spectrometry

Section: Chapter Questions

Problem 11.10QAP

See similar textbooks

Similar questions

In the technique of high performance liquid chromatography (HPLC) the peak area response for a particular analyte is directly proportional to concentration Analgesic tablets typically consist of aspirin and caffeine as the active ingredients, the remainder made up of inert binding material. The concentrations of aspirin and caffeine may be routinely monitored using HPLC, whereby the peak areas obtained from a solution of the tablet are compared with those obtained from standard solutions of the analytes. In an analysis to determine the concentration of caffeine in such a tablet, the following data were recorded: Solutions Analysed: Tablet Sample: Mass of tablet (dissolved in 250 cm methano): 0.523 g Caffeine Standard: Mass of caffeine (diessolved in 500 cm methanol) 0.105 g HPLC results: Solution Peak Area (catfeine) 1. Tablet Sample 325 2. Caffeine Std. 865 The concentration of caffeine in the tablet (expressed as a mass (w/wl percentage) was Oa 1.89 Ob 13.4 O 3.77 Od. 267 Oe 7.54 You…
A standard method for analyzing aspirin tablets has a known variance of 20. A sample of 10 aspirin tablets is selected and analysed for the amount of aspirin using a modified method, yielding the following results: 254, 249, 252, 252, 249, 249, 250, 247, 251, 252. Determine whether the precision of the modified method is significantly different from that of the standard method at, alpha(a) = 0.10
In a survey of 1000 large corporations, 250 said that, given a choice between a job candidate who smokes and an equally qualified nonsmoker, the nonsmoker would get the job (USA Today).(a) Let p represent the proportion of all corporations preferring a nonsmoking candidate. Find a point estimate for p.(b) Find a 0.95 confidence interval for p.(c) As a news writer, how would you report the survey results regarding the proportion of corporations that hire the equally qualified nonsmoker? What is the margin of error based on a 95% confidence interval?
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?
C. Nickel in a sample was determined using a new procedure where six replicate samples resulted in a mean of 19.65% and a variance of 0.4524. Five replicate analyses where conducted using a standard procedure resulting in a mean of 19.24% and a variance of 0.105. If the pooled standard deviation was +0.546, is there a significant difference between the two methods?
A titrimetric method for the determination of calcium in limestone was tested with the analysis of a NIST limestone containing 30.15% CaO. The mean of the four analyzes is 30.26% CaO with a standard deviation of 0.085%. From the data accumulated from many analyzes, s→ϭ=0.094% CaO was found.a) Do the data indicate the presence of systematic error at the 95% confidence level?b) When a value for ϭ is unknown, do the data show a systematic error at the 95% confidence level?
Chemistry In an analysis of the content of carbohydrate present in a glycoprotein, the following results were found: 12.6, 11.9, 13.0, 12.7 and 12.5 g of carbohydrate per 100 g of protein. Taking into account that σ is unknown, the confidence interval for the average value at a 90% confidence level of the carbohydrate content is: Select one:to. 12.5 ± 0.4b. 12.5 ± 0.2c. 12.5 ± 0.5d. 12.5 ± 0.3
3. Seven analyses for the phosphorus content of a fertilizer resulted in 16.2, 17.5, 15.4, 15.9, 16.8, 16.3, and 17.1%. Find (a) the standard deviation, s, , and (b) the 95% confidence interval for the true value, H. 4. The following five values were obtained for the wt % of an organic acid in a sample: 30.3, 31.1, 32.6, 36.7, 28.9. Determine if the value of 36.7 may be rejected at the 90% (two-tailed) confidence level. 5. The concentration of a NaOH solution is determined in a single experiment by titrating a weighed sample of pure, dried KHP (MW = 204.229) with the NaOH. The data are: Weight of KHP = (11.6723 + 0.0001) - (10.8364 ±0.0001) g Volume NaOH = (32.68 + 0.02) - (1.24 + 0.02) mL Where the standard deviations are o, values. (a) What is the molarity of the NaOH? (b) Based on the propagation-of-error formula, what is the standard deviation of the molarity,oM ?
An analysis of city drinking water for total hardness was done by two students in the laboratory and produced the following results (in ppm CaCO3): Student A: 228.3, 226.4, 226.9, 227.1, and 228.6. Student B: 229.5, 226.1, 230.7, 223.8, and 227.5What is the 95% confidence interval for the mean?
An atomic absorption method for determination of copper in fuel samples yielded a pooled standard devia- tion of spooled = 0.27 µg Cu/mL (s). The analysis of an oil from a reciprocating aircraft engine showed a copper content of 7.91 µg Cu/mL. Calculate the 95 and 99% confidence intervals for the result if it was based on (a) a single analysis, (b) the mean of 4 analyses, and (c) the mean of 16 analyses.
9) Using error propagation formulas, find (i) the absolute uncertainty and (ii) the percent relative uncertainty for each of the following operations. (a) 6.1 (+0.3) – 3.6 (±0.2) = ? (b) 9.56 (+0.06)X 0.017 (+0.002) = ? (c) [6.9 (±0.3) – 3.9 (±0.2)] ÷ 9.32 (±0.04) = ? (d) 8.24 (+0.06)X {[6.9 (±0.3) X 10-3] + [4.2 (±0.2) X 10-3]} = ?
A clinical chemist obtained the following data for the alcohol content of a sample of blood: % C,H OH: o.084, 0.089, and o.079. Calculate the 95% confi- dence interval for the mean assuming that (a) the three results obtained are the only indication of the precision of the method and that (b), from previous