During your first day on the job as a research assistant, you are preparing 50 mL of hybridization solution with the following components and working concentrations: 50% formamide 5X sodium salt citrate 0.5% sodium dodecyl sulfate You start from the following concentrated stock solutions: 100% formamide 20X sodium salt citrate 20% sodium dodecyl sulfate How much of each concentrated stock solution and water will you add?

1. Explain the differences in melting point of these test compounds by relating with their structures and intermolecular or intramolecular forces of attraction: a. benzoic acid and salicylic acid b. p-aminobenzoic acid and salicylic acid c. oxalic acid and succinic acid d. succinic acid and malic acid Please provide link for citation.

Considering the procedure below: “Determination of the concentration of HCl: Pipette 10 mL of hydrochloric acid and transfer to a 100 mL volumetric flask, complete the volume with water and homogenize. Remove a 10 mL aliquot of this solution and transfer it to a second dilution in a 100 mL volumetric flask, complete the volume with water and homogenize. Take a 20 mL aliquot of this last solution and transfer to a 250 mL erlenmeyr and add 20 mL of distilled water and 4 drops of the acid-base indicator. Titrate with a previously standardized 0.100 mol/L sodium hydroxide solution until the indicator turns.” Answer: a) In this titration, the indicator used is phenolphthalein. Discuss the use of this indicator considering its turning range and pH at the stoichiometric point of the titration. Justify. b) Considering that the volume of titrant used was equal to 24.5 mL, calculate the concentration of HCl in the sample in mol/L.

6.0 mL of cyclohexanol, 8 mL of 85% phosphoric acid, and 10 drops of sulfuric acid are added to a 50-mL round-bottom flask with boiling chips, and the mixture is distilled into an ice-cooled receiver. The distillate is in the form of a colorless bi-phasic mixture. The cyclohexene upper layer is removed from the water layer, and dried over anhydrous calcium chloride. Isolated is cyclohexene as a clear and colorless foul-smelling liquid. Weighing data is given below. Gross mass: 51.24 g Tare mass: 48.04 g Product mass: 3.2g Question:  Calculate the theoretical mass of the cyclohexene product, bearing in mind that the cyclohexanol starting material was measured by volume, not by mass (so you must use the density of cyclohexanol to convert milliliters to grams, before calculating the number of moles). Calculate the percent yield of cyclohexene obtained.

MAKE A METHODOLOGY : MATERIALS/ REAGENTS WITH SCHEMATIC DIAGRAM . THE PICTURE UPLOADED SERVES AS A GUIDE, DO THE SAME THING BASED FROM THE PIC.  Procedure: Place 20 drops of each of 0.2M CuSO4 in a centrifuge tube. Then add 5 drops of freshly prepared 6M (NH4)2S to each centrifuge tube. Record your observation. Centrifuge the mixtures for 3 mins.  and decant the supernatant liquid. Add 10 drops of DI water and 10 drops of 6M HNO3. Stir and boil the mixture in a hot water bath for 5 mins.  centrifuge the mixture for 3 mins. Decant the supernatant solution from procedure 3. Discard the To each of the supernatant liquid, add 6 drops of 6M H2SO4. Allow themixtures to cool and 5 drops of DI water. To the mixtures in procedure 4, add few drops of concentrated NH3 until the solution becomes basic. Confirm using a litmus paper. Record your observation. Add 1 drop of 5M NaOH and 1 drop of 0.1 M SnCl2 to the centrifuge tube containing Bi3+ ion , centrifuge and decant the supernatant liquid. To…

2.1g of sample are dissolved in methylene chloride and the sample is extracted with  aqueous solutions of acid and base.  Three compounds are isolated - 0.8g of ethyl p-aminobenzoate, 0.6 g of acetanilide, and 0.5 g of benzoic acid.  Calculate the % recovery for the procedure. (Round the answer to the nearest  tens place.) Give just the number, not a % sign.)

which of the following statements regarding purification by recrystallization is false? i. activated charcoal removes insoluble impurities. ii. water is the best recrystallization solvent for organic compounds. iii. slow cooling permits the exclusion of the solvent from the recrystallized solid.   a. i, ii, and iii b. i and ii c. i only d. ii and iii

Write TRUE if the underlined word/phrase makes the statement correct. Otherwise, write the correct WORD/PHRASE that will make the statement true. If there are two bold words/phrases in a number, write your answer for EACH of the bold words/phrases 1. 6-hydroxy-1-naphthoic acid is soluble in 5% NaOH and soluble in 5% NaHCO3. 2. The addition of excess charcoal would decrease the % recovery in the purification by recrystallization. 3. If the target compound is contaminated with impurity, the melting point will be higher than the theoretical value and the melting range is large.

How do you prepare this solution? 10ml of 20% (w/v) L-arabinose stock (weight/volume). How much of L-arabinose and water do you need to prepare desired arabinose stock

You were given a mixture of two miscible solvent A and B that you are tasked to separate. You know that solvent A has a boiling point of 49 oC while solvent B has a boiling point of 174 oC. Which of the listed method would overall be the most efficient?    Fractional distillation Recrystallization Solid-liquid extraction Liquid-liquid extraction Simple distillation Acid-Base extraction