1. Pure compounds have higher (and sharper) melting points than compounds that contain impurities. However, after carrying out their procedure in week 3, some students find that their sample(s) after recrystallization have lower melting points than their sample(s) before recrystallization. Give an explanation for why this might sometimes
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- Explain the reasons for the importance of crystallization step involved in the manufacturing of bulk drugs?The position of the phases in the separatory funnel (whether the top or bottom phase) is dependent on the relative densities of the solvents. Complete table 1 to indicate whether each of the solvents will be on the top or bottom layer. Table 1. Solubility properties of common organic solvents. Solubility in H20 (g/L, 20-25°C) 9.5 x 10-3 1.79 8.09 17.5 Solubility of H20 (g/L, 20-25°C) 0.31 Phase layer Density (g/mL, 25°C) 0.661 Liquid hexane benzene chloroform 0.76 0.87 1.76 15 170 0.877 dichloromethane diethyl ether 1-butanol 60.5 73 0.3 1.489 1.327 0.713 0.81 0.83 1-octanol 49 ethyl acetate 83 33 0.902A student in New York City carried ou1t a boiling point determination for cyclohexane {b.p. 81• C) according to the procedure in this laboratory manual. Will this student's observed boiling point be the same as the value obtained by another student in Denver, Co'lorado.{Nicknamed the "Mile-High City" due to its high elevation)? Will it be lower or higher? Ex plain your conclusion.
- C. Fractional Distillation SAMPLES °C at which vapors are collected Distillate Methanol + Ethanol 65 Hexane + Acetone 56 2-propanol + 2-Butanol 821 2 Which of the following procedures would give the result in test tube #2? O Mixing rennin with milk then Incubating at 37 °C. O Mixing rennin with milk then incubating continuously in ice. O Mixing rennin with 0.1 N NaOH before adding milk. O Mixing rennin with milk then incubating in boiling water. O Boiling rennin before adding milk.A student has a mixture of two possible compounds. The student performs recrystallization to separate the two compounds. The student decides to identify the separated compound by melting point. The student’s compound has a melting range of 108-109 °C using a ramp rate of 2°C/min. The student’s partner believes that they isolated compound 2, while the student thinks they have compound 1. Choose the best answer to go with this scenario. Compound 1 Literature Melting point: 111 °C Compound 2 Literature Melting point: 104 °C A) It is correct that they definitely have compound 2. B)The students have neither of the two compounds. C) The ramp rate is too high so the experimental melting range is not accurate. D) The students likely have compound 2, but should do a mixed melting range experiment with a standard of compound 2 to be certain. E) They did not separate the compounds properly, and it is still a mixture. F) The students likely have compound 1, but should do a mixed melting range…
- 3. Describe the characteristics that a crystal obtained through recrystallization must have, the final crystal, not the solvent.Which of the following statements is true when considering temperature during a recrystallization? More than one answer may be correct. Using ice to cool the sample will speed up the crystallization process so that large crystals will be formed. It is important that the sample is dissolved in just enough hot solvent. O Ideally the hot solvent used will keep the impurities dissolved OR not dissolve them at all. Enough cold solvent should be added to dissolve the sample BEFORE heating it past its boiling point.The boiling points for the compounds are 118 °C and 35 °C respectively. The solubility for both compounds is the same (8g/100g water). Explain this observation for (i) boiling point disparity; (ii) solubility similarity H-bonds form in diethyl ether; n-butyl alcohol forms H-bonds in water H-bonds form in n-butyl alcohol; diethyl ether forms H-bonds in water H-bonds in n-butyl alcohol; Both compounds form H-bonds in water O Both compounds form H-bonds; Both compounds form H-bonds in water
- In distillation 1. What is the reason for discouraging the formation of bubbles inside the condenser?2. What is a fractionating column?3. How fractional distillation works?4. What are azeotropes?TRUE OR FALSE, if false then give the correct word to make the statement true then explain 1. Sublimation occurs when a solid has a relatively high vapor pressure at a temperature [above] its melting point. 2. To isolate the desired chemical, a single extraction is [more efficient] than extracting the compound numerous times. 3. The compounds are separated in liquid-liquid extraction based on their relative solubilities in two [immiscible] liquids.The melting point of benzoic acid is reported in the literature as 122.3°C. What can you deduce if the melting point of the benzoic acid you have prepared is 121.6°? * A- The product may not be benzoic acid. B- The benzoic acid may still contain hydrochloric acid and sodium chloride that have not been washed out. C- The benzoic acid may not have dried completely yet. D- The first three options are all correct. E- The first three options are incorrect.