2. DECOLORIZATION Dissolve 1g of brown sugar in 15 ml. dist. Water in a small beaker and divide the solution into two equal portions. Place one portion in a test tube and add 1 g boneblack or activated charcoal and gently boil over a small flame for about 2 minutes (replace water lost by evaporation). Allow to cool and filter. How does the filtrate compare with the original solution? What property boneblack is exhibited in this procedure? How do you define this property?
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- 3. What is particulate gravimetry? When do we use this technique? 4. What are the conditions for a successful gravimetric analysis. 5. Define nucleation. What conditions are important for this stage.1. Which of the following is the best option for transferring 20 mL of a solution? a.Use a 5mL serological pipette 4 times b. Use a 10 mL Mohr pipette twice c. Use a 20 mL Mohr pipette once d. Use a 10 mL volumetric pipette twice 2. Which glassware is NOT used in preparing a solution from a solid sample? a. Funnelb. Beakerc. Volumetric pipetteIn what order should the following methods be used to separate a mixture containing sand-sugar-alcohol and water into its components? 1) Adi distillation II) Fractional distillation HII) Filtration under vacuum B. II, I, II C. III, I, II D. 1, III, II E III, II, I
- PART 3- LABORATORY EQUIPMENT EQUIPMENT NAME FUNCTION To hold test tubes. Attaches to a retort stand to support glassware being heated. To pour liquid from a large container into a small container. To provide a flame during an experiment. ones To light the Bunsen burner. To attach test tubes to a retort stand. To clean substances out of a test tube. To hold a hot crucible or flask. To hold a hot test tube. To place on the lab bench to prevent burning or to use with ring clamp. To transfer small amounts of liquid. To grow bacteria or contain small experiments. To hold liquids. To measure liquids. To contain experiments (a stopper can be used to close the flask). To hold a hot beaker. To perform an experiment with a different substance in each well. To hold chemicals and perform experiments in. To scoop and transfer small amounts of substances, To stir during experiments that involve mixing or dissolving.25. In the paper chromatography experiment on food dyes, salt water was used as the A. mobile phase B. stationary phase C. eluent D. solute E. sample spotsWhen the compounds analyzed by Robrob were passed on to the next test, another scientist, Kikoko, needed to determine the molecular weight of the ctive compound. They created a solution with a concentration of 20.0%w/w from the solid active compound and the solution had a density of 1.40 g/mL. From this solution, 10µL was taken and mixed with 190µL of reagent and water. It was analyzed and showed a concentration of 5x10-4 M compound. a. What is the concentration (in molarity) of the 20%w/w solution? b. Why was the concentration of the solution expressed as %w/w initially? c. What is the molecular weight of the active compound?
- What is an advantage of Gas Chromatography and Mass Spectrometry (GS/MS). a. It is time consuming. b. It is labor intensive. c. It provides the most accurate confirmation of indentification. d. Substances with high boiling points are not compatible.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.Volumetric pipettes are designed to deliver a precise amount of liquid, but only if you a. submerge the end of the pipette into a solution you are delivering. b. allow the pipette to drain freely, and leave any residual solution in the pipette. c. hold the pipette at a 45 degree angle and ensure that all the liquid is delivered.
- High performance liquid chromatography (HPLC) can be used to : a. identify the various pigments from a leaf extract. b. separate types of organic pesticides. c. determine the mercury content of a fish sample d. all of the above are correctYou are given a container with Na3PO3 that is reportedly contaminated. You are asked by your supervisor to determine the percent purity of that sample in order to know the next measures to be taken by the plant. The following are the procedures that you need to do: a. Dissolve sample weighing 1 g in 35 mL water. b. Prepare solution with 45 mL 3% w/v HgCl2, 30 mL 10% w/v C2H3NaO2 and 10 mL CH3COOH. c. Digest sample then filter then rinse the precipitate that weighs 0.2857 g. d. Compute for the % purity.1. In thin layer chromatography (TLC), explain how the pigments separate on a piece of paper. 2. If the spots are colorless on a TLC plate, how can you make it visible? Enumerate 2 ways and discuss each.