Lab 3 SCC 251 Isolation of Caffeine from Tea Leaves

A 0.1 g amine-containing compound is dissolved in water then diluted to 100 mL. You subject it to spectroscopic analysis, in order to get the concentration of amine in this compound. Next, you get 1 mL of the previously diluted sample then dilute it again to 250 mL for measurement. Then, you fill 3/4 of a 1-cm cuvette with this diluted sample, and you run an analysis using an AAS. The recorded absorbance is 0.545 at 410 nm. What is the molecular weight of the compound? (The molar absorptivity is 1.23 x 104 cm-1 mol-1 L.)

How do you separate sodium hydroxide from the crude mixture?

you weigh your crude sample (1.538 g) and recrystallize with hot isopropanol. How do you know how much isopropanol to add?

Table 1. Solubility Tests. Functional Group Observations (specify type if any) Sample in concentrated (+/-) H2SO4 Color orange Hydroxyl group Hydroxyl group Hydroxyl group 1-butanol Color orange 2-butanol Color orange diisopropyl ether Look at the structures of compounds tested for solubility in concentrated H2SO4. What generalization can be made for a substance to be soluble in concentrated H2SO4 ?

10 mL of 10 % sodium sulphate solution into a clean test tube. Add 1 drop of 10 % barium chloride. What do you observe? Write an equation to explain your observations in your lab report. C2. Measure out a fresh 10 mL portion of 10 % sodium sulphate into another test tube. Making sure to count the drops, use a dropper to add 30 % calcium chloride solution. Swirl the solution after each drop. Continue until a white precipitate occurs. Write an equation to explain your observations. Which solubility product has the smaller numerical value, that for calcium sulphate or barium sulphate? Explain how you know this is true. C3. Measure out another 10 mL portion of 10 % sodium sulphate into a clean test tube. Add 8 drops of 50 % sulphuric acid and swirl. Count the number of drops (swirl after each drop) of 30 % calcium chloride needed to produce a precipitate of calcium sulphate. Explain why the number of drops of calcium chloride differs in the two experiments. I need equations, observations…

To which sample solution the spike will be add?  the distillate>130C the mass standard the distilled <130C

Tom, an analytical chemist, bought a bag of decaffeinated coffee from a grocery store. However,Tom suspected that he might have received regular coffee and therefore decided to analyze hiscoffee for caffeine. In the lab, he took 0.5 mL of the brewed coffee and diluted it in water tomake a 100.0 mL solution. He performed four analyses and found the concentrations to be 4.69,3.99, 4.12, and 4.50 mg/L, respectively. (Assume the density of all solutions is 1.000 g/mL,1oz= 28.35 mL).(a) Report the concentration (in mg/L) of caffeine in the brewed coffee using the format asaverage ± standard deviation. (Note this is not the concentration in the diluted solution.)(b) Look up the caffeine content of regular vs. decaffeinated coffee. Do you think that Tom wasgiven the wrong type of coffee?(c) Caffeine intake of 300 mg per day reportedly has no adverse effects in the vast majority ofthe adult population. If Tom drinks 3 cups (8 oz/cup) of this coffee daily, is his intake withinthis known safe…

Subject-advance maths

Pcdotte Use a flow chart to show how you could separate a mixture of the following compounds using an extraction. Be sure to include all steps to get pure materials. НО.

Series 9. Mixtures Brass Sand + CuSO4• 5H2O White wine Series 9. Mixtures (continued) Water and BaSO4 Oil and water Vinegar

3. Describe the characteristics that a crystal obtained through recrystallization must have, the final crystal, not the solvent.

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 are tasked with performing a recrystallization. You have 3 potential solvents to use, but you don't know which one will work. How will you go about deciding which solvent to use?

You wash a separatory funnel with soap and water to ensure it is clean before extracting an aqueous solution with dicholormethane. You should take the time to make sure there are no drops of water left inside the separatory funnel. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True False

please highlight the correct answer

6. Suppose you have a mixture of water and your 2-bromo-2-methylbutane product in a separatory funnel. Use densities to predict which phase will be the top layer in the funnel. a. 2-bromo-2-methylbutane (organic phase) b. water (aqueous phase) c. there would only be one phase since the substances are miscible

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.  Upon addition of the hot water, you have some white precipitate still at the bottom of the test tube, and the supernatant liquid is poured off.  To this liquid, potassium chromate (K2CrO4) is added.  Upon this addition of potassium chromate, you observe no formation of precipitate. Which of the following is a valid conclusion to draw at this point? (Choose one.)   Select one:   1. Hg22+ is definitely present.   2. Pb2+ is NOT present. 3. Ag+ is definitely present. 4. Pb2+ is definitely present.

A 0.1 g amine-containing compound is dissolved in water then diluted to 100 mL. To get the concentration of amine in this compound, you subject it to spectroscopic analysis. So, you get 1 mL of the previously diluted sample then dilute it again to 250 mL for measurement. Then, you fill 3/4 of a 1-cm cuvette with this diluted sample then you run an analysis using an AAS. The recorded absorbance is 0.545 at 410 nm. Solve for the molecular weight of the compound. The molar absorptivity is 1.23 x 104 cm-1 mol-1 L.

You want to determine the concentration of NaCl in a water. In preliminary analysis, it appears to be saline water with a NaCl content of approximately 4%. Should you dilute the sample if your titrant has a concentration of 0.1 M and you want to spend 25 mL of sample? Solution: You must dilute approximately ten times, taking 10 mL of sample and making up to 100 mL. In this way, 17.20 mL of titrant will be spent.

A mixture of the two compounds shown below is dissolved in ether. Using the information given in the experiment, select all the correct statements regarding the extraction and isolation of the two compounds. X "NH₂ OA. X can be extracted from the organic layer using sodium hydroxide. О в. Y can be extracted from the organic layer using sodium hydroxide. OH Y OC. X can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of X. OD. Y can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of Y.

Please see attached image.

Q2. What does “crude” product mean? Q3. What is the advantage of using Buchner filtration in filtering crystals? Q4. Briefly explain how scratching the wall of the glass flask can help formation of crystals. Q5. Briefly explain why crystals form as the solvent cools during recrystallization.

How to determine the difference between primary , secondary and tertiary alcohol in the laboratory

What is Van dorn water sampler

5.0 mL of 1-butanol was mixed with 10 mL of HCl. The reaction was put on an ice bath and 4 mL of concentrated sulfuric acid was added. This mixture was refluxed for 45 min and then the product was co-distilled with water using a simple distillation apparatus. Water and the product are immiscible. 1-butanol has a molar mass of 74.12 g/mol, a density of 0.810 g/mL, and a boiling point of 118 C. The product has a molar mass of 92.57 g/mol, a density of 0.880 g/mL, and a boiling point of 78 C. What is the nucleophile in this reaction? What is the role of H2SO4 in this reaction? Calculate the theoretical yield for this reaction. Give your answer in grams.  Select the following statements that can be said about the reaction shown.

6. Explain the reason why a laboratory analyst should not return excess or unused chemicals back in their respective reagent bottles.

Which one answer does NOT represent a characteristic of a good recrystallizing solvent? O 1) Should not react with sample. O 2) Should do a poor job of dissolving impurities when hot. O 3) Should have a moderate boiling point. O 4) Should do a good job dissolving a sample when cold.

What is the purity test of synthesized aspirin and commercial aspirin?

How do fill in the Flow Diagram for the Mixtures using the information presented?

3. What is the major obstacle that fractional distillation overcomes? 1 1° in422 male distillatio