Assignment: This is an individual activity. After studying the lesson and watching all the videos, answer the following questions. Answer in not more than 3 sentences per question. 1. Discuss the a) direct method of weighing b) indirect weighing using the analytical balance. 2. Explain how suction filtration is carried out in the laboratory. Give the important points that must be observed in doing the process. 3. Explain why it is important to wash the precipitate. Can distilled water be used to wash all types of precipitates? 4. Discuss how to use a desiccator. When should a desiccant be replaced?

Assignment: This is an individual activity. After studying the lesson and watching all the videos, answer the following questions. Answer in not more than 3 sentences per question. 1. Discuss the a) direct method of weighing b) indirect weighing using the analytical balance. 2. Explain how suction filtration is carried out in the laboratory. Give the important points that must be observed in doing the process. 3. Explain why it is important to wash the precipitate. Can distilled water be used to wash all types of precipitates? 4. Discuss how to use a desiccator. When should a desiccant be replaced?

EBK A SMALL SCALE APPROACH TO ORGANIC L

4th Edition

ISBN:9781305446021

Author:Lampman

Publisher:Lampman

Chapter80: Crystallization: Purification Of Solids

Section: Chapter Questions

Problem 4P

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1. Discuss the a) direct method of weighing b) indirect weighing using the analytical balance. 2. Explain how suction filtration is carried out in the laboratory. Give the important points that must be observed in doing the process. 3. Explain why it is important to wash the precipitate. Can distilled water be used to wash all types of precipitates? 4. Discuss how to use a desiccator. When should a desiccant be replaced? PreviousNext
Accurately weigh out about 6g copper(ii) sulfate crystals into a weighing boat. Use the copper(ii) sulfate crystals to make up 250cm3 of standardized copper (ii) sulfate solution Pipette 25cm3 of this solution into a conical flask Add 1.5g potassium iodide and swirl thoroughly Titrate this solution with standard 0.1 moldm-3 Na2S2O3 in a burette. When the iodine color fades, add 1 cm3 starch indicator. Use your titration data below to calculate the percentage by mass of copper in the copper(ii) sulfate crystals.
a) When considering the overall dialysis procedure, why is it important to exchange old/used dialysis buffer (or “dialysate” solution) with a fresh dialysis buffer solution at least once throughout the process? NOTE: Your TAs will do this for your group’s samples over the next week. b) This week’s lab utilizes a dialysis buffer with the following composition: 10 mM Tris-HCl, 10 mM MgSO4, and a pH of 7.4. Let’s presume an ERROR occurred with the creation of this buffer during the pH titration and you unknowingly titrated to a final pH of 5.0. What effects, if any, could you expect to observe on your final, dialyzed sample?
Help with the CHEM Lab report please! It is about Volumetric Analysis There is also a Burn trail please make sure for that!
Because of the risk of lead poisoning, the exposure of children to lead-based paint is a significant public health concern. Thefirst step in the quantitative analysis of lead in dried paint chips is to dissolve the sample. Corl evaluated several dissolution techniques.24 In this study, samples of paint were collected and pulverized with a Pyrex mortar and pestle. Replicate portions of the powdered paint were then taken foranalysis. Results for an unknown paint sample and for a standard reference material, in which dissolution wasaccomplished by a 4–6-h digestion with HNO3 on a hot plate, are shown in the following table. (a) Determine the overall variance, the variance due to the method, and the variance due to sampling. (b) What percentage of the overall variance is due to sampling? (c) How might the variance due to sampling be decreased?
Should your calibration curve go through the origin? Why? Or why not? in the solubility lead iodine lab experiment
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
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
Volumetric Analysis The mass of KHC8H4O4 is measured to the nearest milligram; however, the volume of water in which it is dissolved is never of concern—water is even added to the wall of the Erlenmeyer flask during the titration. Explain why water added to the KHC8H4O4 has no effect on the data, whereas water added to the NaOH solution, may drastically affect the data.
The Diela Alder reaction used a mixed solvent recrystallization to purify the product. In general describe how a mixed solvent recrystallization works.
Using the solubility information from your table of constants, make a flow chart, showing the procedure you would use to separate 4- chloroaniline from 1,4-dibromobenzene. Indicate what compound is in each solvent by writing the structures at the appropriate locations in the flow chart. please answer the question, and draw the chart.
A student was careful to make and stir all of her standard solutions immediately before measuring their turbidity for her calibration curve. However, she let her tap water solutions sit for 10 minutes prior to measuring their turbidity. If she measured the top portion of the solution, would her experimental sulfate ion concentration be higher or lower than it should be?