Before determining the amount of Na2CO3 in an unknown sample, a student decides to check her procedure by analyzing a sample known to contain 98.76% w/w Na2CO3. Five replicate determinations of the %w/w Na2CO3 in the standard were made with the following results 98.71% 98.59% 98.62% 98.44% 98.58% Is the mean for these five trials significantly different from the accepted value at the 95% confidence level (α = 0.05)

Before determining the amount of Na2CO3 in an unknown sample, a student decides to check her procedure by analyzing a sample known to contain 98.76% w/w Na2CO3. Five replicate determinations of the %w/w Na2CO3 in the standard were made with the following results 98.71% 98.59% 98.62% 98.44% 98.58% Is the mean for these five trials significantly different from the accepted value at the 95% confidence level (α = 0.05)

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter14: Chromatography

Section: Chapter Questions

Problem 9P

See similar textbooks

Similar questions

If an instrument gives a response of 1240 for a standard containing 8 ppm of a substance, how much if this substance is in a sample that gives a response of 1705? Are any assumptions needed?
Chemistry The levels of an organic pollutant (P) in the groundwater at the perimeter of a plant were a cause for concern. A 10 mL sample of the water was taken and the pollutant was extracted with 95% efficiency using 25 mL of diethyl ether. GC was used to analyse the concentration of P in diethyl ether. A calibration curve was plotted for a series of standards of P which yielded the following results: Peak Area Toluene Conc. (µg/ml) 12,000 2.6 23,700 5.0 35,500 7.7 46,800 9.9 31,250 Sample Determine the concentration of P in ppb in the initial groundwater sample.
The gravimetric factor used to express CoCBr6·H20 in a sample that is finally weighed as PbClBr is choose below: FW PbClBr / 6 x FW CoCBr6·H20 FW CoCBr6·H20 / FW PbClBr FW CoCBr6·H20 / 6 x FW PbClBr 6 x FW PbClBr / FW CoCBr6·H20
In quality management, it is very important that you have a good background knowledge in both descriptive and inferential statistics. Since you already took up Biostatistics and Epidemiology during your Second Year, answer BRIEFLY the following questions on basic statistics: 1. Compare and contrast the three most common measures of central tendency mean, median and mode. 2. Differentiate standard deviation from coefficient of variation. 3. What is T-test?
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?
Often the analyst will compare known quantities of analyte to unknown quantities of the material to be analyzed. This may be done in one of three ways: -use calibration curves; use standard additions; or use internal standards. The method of standard additions would be used when A) the quantity of sample analyzed or the instrument response varies from run to run. B) the standard solutions and the unknown solution all have similar characteristics are unaffected by the other material in the sample. C) the sample composition is unknown or complex and affects the analytical signal.
The concentration of purified OXA-M290 is tested with a BCA assay. Serial dilutions of a bovine serum albumin (BSA) stock solution are prepared, then pipetted into a 96-well plate; each dilution of the BSA standard is tested in triplicate. Then, bicinchoninic acid and Cu2+ ions are added to all of the wells of the plate. After incubating the plate for 1 hour, a microplate reader is used to measure the absorbance of all of the wells in the plate at 560 nm. This generates the following data: BSA conc. (μg/mL), Replicate 1 Absorbance, Replicate 2 Absorbance, Replicate 3 Absorbance 40, 1.360, 1.403, 1.481 20, 0.750, 0.745, 0.810 10, 0.380, 0.344, 0.398 5, 0.198, 0.160, 0.183 2.5, 0.090, 0.100, 0.085 1.25, 0.038, 0.043, 0.051 0.625, 0.024, 0.028, 0.019 Prepare a calibration curve using these data. You can use Excel, R, SPSS or an equivalent graphing software. In this graph, plot absorbance (y-axis) against the concentration of the protein standard (x-axis). Calculate and plot…
Which of the following would result in an increase in the calculated ngas 10, assuming the rest of the parameters are held constant? I. Inserting 23.0 mg instead of the prescribed 15.0mg of folded Mg ribbon into the eudiometer. II. Performing the experiment in a different laboratory with a cooler temperature. III. A shorter equilibration time prior to volume measurement. IV. Acid used was 12.0 M HNO3 instead of 6.0 M HCI.
potassium hydrogen phthalate is a primary standard used to measure the concentration of NaOH solutions. find the true mass of potassium hydrogen phthalate (density=1.636g/ml) if the mass weighed in the air is 4.236g. if you did not correct the mass for buoyancy, would the calculated molarity be too high or too low? the density of air is 0.0012 g/mL while that of the calibration weights is 8.0 g/mL.
Study the tabulated data during an gravimetric analysis of BaSO4 experiment Trial T1 T2 T3 Mass of sample (g) 1.0040 1.0100 1.0050 Constant weight of empty crucible (g) 10.2453 10.2454 10.2454 Constant weight after ignition (g) 10.3253 10.3252 10.3253 1. Calculate the mean mass of precipitate as BaSO4 a. 0.0799 g b. 0.0800 c. 0.08 g 2. Calculate the mean weight of sulphate (MM BaSO4 = 233.39 g/mol, So42- = 176 g/mol)? a. 0.0603 g b. 0.06 g c. 0.06025 g 3. Calculate the mean % SO42- in the sample a. 6.00% b. 5.991% c. 5.9908%
Identify the effect of the condition on the indicated parameter. Write increase, decrease, or no effect , and provide an explanation The actual concentration of the sodium hydroxide used in the calibration part of the experiment was lower than the stated value. However, the NaOH solution used in the determination of ΔHrxn was of the correct concentration. [magnitude of ΔHrxn]
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