2024 UNH CHEM 546 PRE-LAB
LABS 1-9 QUESTIONS WITH
CORRECT ANSWERS
Which of these statements below best describes MISCIBLE liquids? -
CORRECT-ANSWERSTwo liquids that mix homogeneously (1 layer)
Which of these statements below best describes IMMISCIBLE liquids? -
CORRECT-ANSWERSTwo liquids that do NOT mix homogeneously (2 layers)
What kind of technique is Thin-Layer Chromatography (TLC)? - CORRECT-
ANSWERSa fast, qualitative analysis of organic compounds in a mixture
What is the standard stationary phase used in TLC? - CORRECT-
ANSWERSsilica gel
When you "spot" a TLC plate, what are you doing? - CORRECT-ANSWERSyou
are applying a spot of the sample to be analyzed to the bottom of the TLC
plate using a capillary tube
Some compounds separated on a TLC plate are colorless and cannot be seen
by the naked eye. In this case, what common methods are utilized to see the
spot(s)? Choose all correct answers below. - CORRECT-ANSWERSuse a
visualization reagent like iodine to darken the spots on the TLC plate
shine UV light on the plate after solvent has evaporated
What does IR spectroscopy allow us to determine? - CORRECT-ANSWERSThe
types of bonds in a compound
The peaks observed in infrared spectroscopy correspond to: - CORRECT-
ANSWERSThe energy absorbed by a molecule for a specific bond vibration
Which of the following signals in an IR spectrum would confirm the presence
of a carboxylic acid (RCOOH)? - CORRECT-ANSWERSA C=O stretch at ~1700-
1725 cm-1 and an O-H stretch at ~2500-3500 cm-1
A C-H bond will give a peak around 3000 cm-1 on an IR spectrum. The exact
location can give insight on the hybridization of that carbon atom. Sp2
hybridized carbons typically show =C-H peaks: - CORRECT-ANSWERSAbove
3000 cm-1
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