Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Organic Chemistry Lab
Organic Chemistry Laboratory I (X36.1A)
For each question, write the letter of the correct answer in the column on the right :
1. Recrystallization is a laboratory procedure that is usually performed in order to-
A) increase the yield of the product of a reaction
B) separate enantiomers
C) determine whether a compound is polar or non-polar
D) increase the purity of the product of a reaction
E) lower the melting point of the product of a reaction
2. Why is benzene (C6H6, boiling pt. 78°C) not used as a recrystallization solvent?
A) because it is non-polar
B) because it is an aromatic compound
C) because its boiling point is too low
D) because it forms explosive peroxides
E) because it is toxic and an environmental hazard
3. Why is pentane (C5H12, boiling pt. 36°C) not used as a recrystallization solvent?
4. The most important reason for adding a boiling stick to a liquid before heating it is-
A) to prevent bumping (overheating) of the liquid
B) to stir the liquid while it is being heated
C) to prevent the liquid from boiling
D) to lower the boiling point of the liquid
E) to absorb impurities that are in the liquid on the surface of the wood
5. Norit® is the name of a company and of its main product, which is-
A) boiling sticks
B) activated charcoal
C) a solvent used for recrystallization
D) weighing paper
E) mother liquor
6. When you have a hot solution from which crystallization will occur, you should-
A) allow it to cool slowly and undisturbed
B) immediately cool it in an ice bath so that crystals will form rapidly
C) stir the solution vigorously with a stirring rod or boiling stick while it is cooling
D) place the solution under vacuum so that solvent will evaporate and crystals will form
E) add boiling chips to prevent “bumping” of the hot liquid
7. If the yield of crystals is small, a second crop of crystals can be obtained by-
A) adding more solvent
B) heating the solution to evaporate some of the solvent and then cooling
C) adding sand from the sand bath
D) adding activated charcoal
E) passing the solution through a Pasteur pipette containing glass-fiber filter paper
8. In a recrystallization procedure, the liquid that remains at the end of the procedure after the purified crystals have been removed from it is called the-
A) cosolvent B) distillate C) rinse D) mother liquor E) water bath
9. In the decolorization of brown sugar (Experiment 6, Part II), activated charcoal is removed by-
A) vacuum filtration
B) distillation
C) extraction with an acidic solvent
D) the glass-fiber Pasteur pipette method
E) centrifugation
10. A boiling stick must be added to a solution before the solution is heated because if a boiling stick is added to a hot solution-
A) the stick may dissolve in the solution
B) the stick may cause crystallization to occur prematurely
C) many bubbles may form quickly and the solution may froth and “bump”
D) the stick will absorb the substance that is being recrystallized
E) the stick will prevent crystallization from taking place
Consider a 75.0g sample of H2O(g) at 125C. What phases are present when 215kJ of energy is removed from this sample?
If an iron atom in this universe contains the same number of electrons as on Earth, and Hund's rule and the Pauli exclusion principle are also true, what is the highest energy orbital for Fe that contains at least one electron
Peptide hormones must bind to receptors on the extracellular surface of their target cells before their effects are communicated to the interior. In contrast, receptors for hormones such as estrogen are intracellular proteins. Why is this possible..
draw the structures of two stereoisomeric alkenes that would give 3-hexanol as the only major product of hydroboration
how many grams of potassium bromide are required to prepare 350 mL of a .200 M solution.
Some 2-methyl-2-butene may be produced in the reaction as a by-product. Give a mechanism for its production.
The preparation of chlorobenzene by the reaction of chlorine with benzene occurs by the reaction C6H6 (l)+Cl2 (g)- ->C6H5Cl (l)+ HCl (g). If 52.6 g of benzene reacts with an excess of chlorine to give 51.6 g of chlorobenzene, what was the percent ..
50ml of 12M HCl are mixed, a ppt of AgCl forms Assume the reaction below goes to completion, and find the value of [Cl] in the mixture: Ag(aq) + Cl(aq)--> AgCl(s)
Consider the following standard heats of formation: Standard Heat of formations for the substances:CO2(g) = -393.5 kJ/mol PbO(s) = -151.6 kJ/mol CO(g)
The addition of bromine to ethene in the presence of high concentration of chloride ion in an inert solvent results in the formation of 1,2-dibromoethane and 1-bromo-2-chloroethane.
What multiple of Ka must the initial concentration of a weak acid exceed, for the initial concentration and the equilibrium concentration to be within 9.86 percent of each other
Al(OH)3 + 3HCl ---> AlCl3 + 3H2O Determine the moles of acid neutralized if a tablet contains 0.200 mol Al(OH)3
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd