Answered: 1) Suppose you use your calibrated…

1) Suppose you use your calibrated 25-mL pipet twice to deliver “50 mL" liquid, what is the actual total volume? What is the error in the final volume?

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter6: Random Errors In Chemical Analysis

Section: Chapter Questions

Problem 6.19QAP

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The tolerance of a Class A 25 mL transfer pipet is +0.03 mL. A student uses an uncalibrated Class A transfer pipet to deliver a total of 125 mL of solution. What is the uncertainty in the delivered 125 mL? mL 0.15 Next, the student calibrates the pipet. The calibrated pipet delivers a mean volume of 24.995 mL with an uncertainty of +0.006 mL. The student then uses the calibrated 25 mL pipet to deliver a total of 124.975 mL of solution. What is the uncertainty in the delivered 124.975 mL? 0.375 mL Incorrect How does the uncertainty in the delivered volume using the calibrated pipet compare to the uncertainty in the delivered volume using the uncalibrated pipet? O The uncertainty in the delivered volume is the same for the calibrated and uncalibrated pipet. O The uncertainty in the delivered volume using the calibrated pipet is greater than the uncertainty in the delivered volume using the uncalibrated pipet. The unceWainty in the delivered volume using the calibrated pipet is less than…
The tolerance of a Class A 25 mL transfer pipet is +0.03 mL. A student uses an uncalibrated Class A transfer pipet to deliver a total of 125 mL of solution. What is the uncertainty in the delivered 125 mL? mL 0.15 Next, the student calibrates the pipet. The calibrated pipet delivers a mean volume of 24.995 mL with an uncertainty of +0.006 mL. The student then uses the calibrated 25 mL pipet to deliver a total of 124.975 mL of solution. What is the uncertainty in the delivered 124.975 mL? 0.375 mL Incorrect How does the uncertainty in the delivered volume using the calibrated pipet compare to the uncertainty in the delivered volume using the uncalibrated pipet? O The uncertainty in the delivered volume is the same for the calibrated and uncalibrated pipet. O The uncertainty in the delivered volume using the calibrated pipet is greater than the uncertainty in the delivered volume using the uncalibrated pipet. O The uncerainty in the delivered volume using the calibrated pipet is less…
You are trying to determine the caffeine content of brand X coffee using HPLC-UV/VIS analysis. You used a C18 column and a water : methanol mobile phase of 60:40 ratio. The detector was set to measure at 275 nm. Fill the blanks in the following table using the correct number of significant figures. Use whole numbers only. Area (μν"sec) Concentration (ppm) Standard Deviation Trial 1 Trial 2 Trial 3 Average (use 3 S.F.) 2.00 69400 70400 69900 4.00 110525 109415 110390 6.00 145467 143405 145759 8.00 197899 196474 197196 10.00 243151 242193 241691
State whether the errors in (a)–(d) are random or systematic:a. A 25-mL transfer pipet consistently delivers 25.031 ± 0.009 mL.b. A 10-mL buret consistently delivers 1.98 ± 0.01 mL when drained from exactly 0 to exactly 2 mL and consistently delivers 2.03 mL ± 0.02 mL when drained from 2 to 4 mL.c. A 10-mL buret delivered 1.983 9 g of water when drained from exactly 0.00 to 2.00 mL. The next time I delivered water from the 0.00 to the 2.00 mL mark, the delivered mass was 1.9900 g. d. Four consecutive 20.0-L injections of a solution into a chromatograph were made and the area of a particular peak was 4 383, 4 410, 4 401, and 4 390 units.
2) What is the relative error in delivering a volume of 18.28 mL from a class A 25 mL buret? (Remember, burets require two readings to deliver a certain volume, pipets only require one reading!) NIST Tolerances for Volumetric Glassware, Class Aa Tolerances (mL) Capacity (mL) (Less Than and Including) Volumetric Flasks Transfer Pipets Burets 1000 +0.30 500 ±0.15 100 +0.08 ±0.08 +0.10 50 ±0.05 +0.05 +0.05 25 +0.03 +0.03 +0.03 10 +0.02 +0.02 +0.02 5 +0.02 +0.01 +0.01 2 +0.006 "Corning Pyrex glassware and Kimball KIMAX, Class A, conform to these tolerances.
10) The following results were obtained in an analysis of iron content in an ore sample. The results reported as % Fe for each analysis, were as follow: Samples no. 1 3 4 5 6 % Fe 20.10 20.50 18.65 19.25 19.40 19.99 i. Calculate the mean and median from the set of the data above ii. If the true value of %Fe is 19.65 %, calculate the value for absolute error and percentage relative error for sample no. 3 Using Q-test, justify whether an of the data must be rejected at 95 % ii. confidence level iv. Calculate the standard deviation and relative standard deviation of the data.
Suppose Marcus needs to transfer 11.50 mL of a liquid with ONLY high precision. Which of the following pieces of glassware provided in the General Chemistry labs (see Appendix A) should Marcus use? Hint: Compare the average percent errors, calculated from the sample data provided, for the buret and pipet trials. O 1.50-mL pipet 25-mL buret O 10-mL pipet with a little over the calibration line O 100-mL beaker
Categorize each as a determinate or an indeterminate error and further classify determinate errors as instrumental, method or personal. a) An unknown sample being weighed is hygroscopic. b) One component of a mixture being analyzed quantitatively by GC reacts with the column packing. c) A radioactive sample being counted repeatedly without any change in condition yields a slightly different count at each trial. d) The tip of the pipet used in the analysis is broken. e) In measuring the same peak heights of a chromatogram, two technician each report different heights.
Location 1 (% C) To determine the organic material in a dried lake bed, the percent carbon by mass is Sample Location 2 measured at two different locations. To compare the means of the two different locations, it must first be determined whether the standard deviations of the two locations (% C) 60.40 60.10 are different. 60.20 60.90 For each location, calculate the standard deviation and report it with two 60.30 60.20 significant figures. 4 60.40 60.70 60.20 60.30 location 1 standard deviation: location 2 standard deviation: What is the calculated F vae for comparing the standard deviations? Fale = Are the standard deviations for the two locations significantly different at the 95% confidence level? O no O yes What is the calculated i value used to compare the means of these two locations? I cale = Are the means for the two different locations significantly different at the 95% confidence level? O no O yes tv hulu
You pipette and weigh a 100 ml sample of water & get the following results for 3 trials: 0.1041g, 0.0979g, 0.0998g. calculate average, % error, mean (or average) deviation, standard deviation, and % deviation
Home Insert Draw View A Text Mode Lasso Select Insert Space + 4. When measuring the volume of a liquid, how would sample size (e.g., using a 10 mL graduated cylinder vs. a 100 mL graduated cylinder to measure out 70 mL of a liquid) affect the absolute error and percentage error in the measured values of mass and volume and therefore the density?
8.0 cm 5.8 cm 3.9 cm 1.5 cm A B C D Figure 2. Developed TLC plate of commercial analgesic and standards Use the data presented in Figure 2 as basis for your answer. The TLC plate used is 5 cm by 10 cm. Note that dot A is for the commercial analgesic, dot B is for the aspirin standard, dot C is for the acetaminophen standard, and dot D is for the caffeine standard. What component/s islare present in the commercial analgesic as confirmed on the developed chromatograph?