Can you proceed with sample analysis even without standardizing the titrant solution? Why or why not? You have finished two trials of the sample analysis for the experiment and you noticed that the burette is almost empty (~5 mL remaining). Should you add more titrant before the next sample analysis or not? Why or why not?

Can you proceed with sample analysis even without standardizing the titrant solution? Why or why not? You have finished two trials of the sample analysis for the experiment and you noticed that the burette is almost empty (~5 mL remaining). Should you add more titrant before the next sample analysis or not? Why or why not?

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter8: Sampling, Standardization, And Calibration

Section: Chapter Questions

Problem 8.2QAP

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How many grams of NaAsO, should be weighed out to prepare a stock solution of 100 mg/L in 500 mL deionized water. Use the stock solution to prepare 4 different standard solution that can be used to prepare an analytical calibration curve to measure the concentration of 750 sample in the concentration range of 10-35 mg/L. Draw a proposed calibration curve (based on the results you achieved).
00 mL of a diprotic acid primary standard solution was accurately prepared to a concentration of 0.1431 M. Three samples of this primary standard solution were used as samples in a titration to standardize an aqueous solution of sodium hydroxide, NaOH, which would be used as a titrant. Using the following table of data for the titration of the primary standard acid with NaOH, calculate the average concentration of NaOH. Trial # Volume of primary standard Initial titrant volume Final titrant volume 1 10.00 mL 8.21 mL 27.22 mL 2 10.00 mL 27.22 mL 46.23 mL 3 10.00 mL 30.28 mL 49.29 mL 0.1506 M 0.0753 M 0.0376 M 0.1431 M 0.0526 M
1. Several procedures for the analysis of caffeine involve extracting the caffeine into an organic non-polar solvent (such as methylene chloride CH2Cl2). This about your experiment and what is discussed in the introduction. What might the advantage be for this approach? What is a disadvantage? 2. Think about what you said in the question above. If your sample was espresso, would your answer change? Why? 3. I was careless and ended up using a wavelength other than the peak (Say 250 nm). Would I still be able to carry out the experiment successfully? What might be the reason that I do not get optimum results? 4. I carried out the experiment using a scratched (or several scratches) cuvet for one standard, and clear cuvets for others. How might my calibration curve change (improve or get worse and why)? Pllllz answer these questions as soon as possible
You have finished two trials of the sample analysis for the experiment and you noticed that the burette is almost empty (~5 mL remaining). Should you add more titrant before the next sample analysis or not? Why or why not? Select one: YES. It will not affect the calculations and not cause error NO. It will affect the calculations and cause error Neither A nor B Cannot be determined
Note that this experiment was performed using qualitative analysis
You obtain an Unknown Sample from the Stockroom. You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file. You first add HCl and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube. Which of the following is a valid conclusion to draw at this point? Pb2+ is definitely present. Hg22+ is definitely present. Ag+ could be present, or Hg22+ could be present, or BOTH could be present. Ag+ is definitely present
Which statement about the determination of the percentage purity of benzoic acid is correct? * A- Only sodium hydroxide solution can be used as the titrant in the volumetric analysis of benzoic acid. B- Analysing a benzoic acid sample that still contains some hydrochloric acid may yield an analyte percentage that is less than expected. C- Analysing a wet benzoic acid sample may yield an analyte percentage that is more than expected. D- All these statements are correct. E- None of these statements are correct.
You obtain an Unknown Sample from the Stockroom. You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file. You first add HCl and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube. You pour off the supernatant liquid, and add ammonia (NH3) to the remaining precipitate. You now observe the formation of a gray-black precipitate. Which of the following is a valid conclusion to draw at this point? Select one: Hg22+ is definitely present. Pb2+ is definitely present. Ag+ could be present, or Hg22+ could be present, or BOTH could be present. Ag+ is definitely present
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Color BEFORE adding Color AFTER adding Intensity of color AFTER adding FeCl3 Test Tube # FeCl3 FeCl3 #1 (salicylic acid) clear lilac 100% #2 (commercial aspirin A) clear slightly pink 50% #3 (commercial aspirin B) clear lilac 95% #4 (aspirin from your clear pink 20% synthesis above) #5 (control) clear clear 0% Based on this data and the melting point of Aspirin, how pure is the synthesized product?