Appl Of Ms Excel In Analytical Chemistry
2nd Edition
ISBN: 9781285686691
Author: Crouch
Publisher: Cengage
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An atomic absorption method for the determination of the amount of iron present in used jet engine oil was found from pooling 30 triplicate analyses to have a standard deviation s = 3.6 mg Fe/mL. If s is a good estimate of σ, calculate the 95 and 99% confidence intervals for the result 18.5 mg Fe/mL if it was based on (a) a single analysis, (b) the mean of two analyses, and (c) the mean of four analyses.
An atomic absorption method for the determination of the amount of iron present in used jet engine oil was found from pooling
30 triplicate analyses to have a standard deviation s = 3.1 µg Fe/mL. If s is a good estimate of o, calculate the 95 and 99%
confidence intervals for the result 21.7 µg Fe/mL if it was based on the following criteria.
(a) a single analysis
95% confidence interval= 21.7 +
99% confidence interval = 21.7 +
(b) the mean of two analyses
95% confidence interval = 21.7 +
99% confidence interval=
(c) the mean of six analyses
21.7 ±
95% confidence interval = 21.7 +
99% confidence interval= 21.7 +
μg Fe/mL
μg Fe/mL
μg Fe/mL
μg Fe/mL
μg Fe/mL
μg Fe/mL
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.
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- 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?arrow_forward(a) For use in an iodine titration, you prepare a solution from 0.222 2 (+0.000 2) g of KIO3 [FM 214.001 0 (+0.000 9)] in 50.00 (+0.05) mL. Find the molarity and its uncertainty with an appropriate number of significant figures. (b) Would your answer be affected significantly if the reagent were only 99.9% pure?arrow_forwardA young researcher was evaluating a standard method for determining the methylmercury content in blue fin tuna using high performance liquid chromatography (HPLC). She determined the standard deviation (?)(s) for the method to be 0.440.44 ppb and assumed that ?s was a good approximation of ?σ . As a test, she used this method to evaluate the methylmercury content in a National Institutes of Standards and Technology (NIST) standard and determined the unknown amount to be within 0.210.21 ppb (?)(μ) of the known mean with 99% probability. How many replicate measurements of the NIST standard did the researcher perform?arrow_forward
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