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Chem 2545 Organic Chem Lab Final Questions and Answers verified
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Chem 2545 Organic Chem Lab FinalQuestions and Answers/ verified
Chem 2545 Organic Chem Lab Final
Questions and Answers/ verified
Organic lab policy requires that the instructor be notified of the following: -
✔️ Allergies to chemicals handled in the lab
Pregnancy
Drugs or medications that may impair normal functioning
Organic solvents and other chemicals may enter the body through the skin -
✔️ True
In the J. T. Baker SAF-T-DATA rating system, the hazard level of a substance is
rated on a scale of: -
✔ ️ 0-4, with 0 being minimum hazard and 4 being maximum hazard
Physical properties such as solubility and melting point can be readily found in
Material Safety Data Sheet for specific chemicals -
✔️ True
A lab instructor is authorized to deny a student entrance into the lab if the student is
wearing -
✔️ A sleeveless garment
Shorts
Tank Tops
Open Shoes
According to UTD Chemistry lab policy, students who are or becoming pregnant
while taking this course must: -
✔️ Obtain a doctor's approval to stay in the course and channel it to the Dean of
Natural Sciences and Mathematics
Students working in the organic lab are required to wear eye protection of the
approved type. However, its not necessary for students to wear safety glasses if the
are not handling chemicals at the time -
✔️ False
The Hirsch funnel is a device used to perform -
✔️ a vacuum filtration to separate crystals from the solvent
According to melting point theory, what effect do impurities typically have on the
melting point of a substance? -
✔ ️ impurities typically cause the melting point to decrease and the melting range
to increase
, Chem 2545 Organic Chem Lab Final
Questions and Answers/ verified
Assume that 215 mg of pure aspirin was obtained from a tablet. What is the percent
recovery if the label on the bottle states that each tablet contains 350 of the active
ingridient? -
✔ ️ 61.43%
Crystallization is a technique that can be used to purify any substance in any
physical state. -
✔️ False
What factors affect the solubility of a substance in a given solvent? -
✔️ its polarity in relation to that of the solvent and temperature
The ideal solvent for crystallization: -
✔️ dissolves the sample at high temperatures, but not at low temperatures
What factors come into consideration when selecting a solvent for crystallization? -
✔ ️ the polarity of the substance to be purified
the polarity of the solvent under consideration
the solubility of the substance in the solvent under consideration at high and low
temperatures
Mixtures of solvents (such as water-ethanol) SHOULD NOT be used in crystallization
experiments -
✔️ True
In crystallization experiments, the term "mother liquor" refers to: -
✔ ️ the solution or supernatant that remains after crystals have formed at low
temperatures
What are some common mistakes made when performing crystallizations? -
✔ ️ heating the solid sample before adding the solvent
adding too much solvent to try to dissolve the solid at low temperatures
losing too much solvent through evaporation when heating at high temperatures
impatiently expecting that crystals will form instantly as soon as the solution starts to
cool
The technique of liquid-liquid extraction can be used to purify solids or liquids -
✔️ True
If an impure sample is in solution in solvent 1, and one wishes to select an extracting
solvent 2 for this
sample, a requirement for solvent 2 is that -
✔ ️ It must be immiscible with solvent 1
In liquid-liquid extraction, the distribution coefficient K is defined as the concentration
of sample obtained
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