Chem 1LD Expt. 7+8 Questions With Complete Solutions
_________ the outside of the cuvette with a Kimwipe and place
the blank in the spectrometer. When taking an absorption
measurement, always align the cuvette with the same face (mark
the top of the cuvette with a grease pencil) pointing toward the
detector. Why is this necessary? Correct Answers wipe
- absorption may be read incorrectly if facing the wrong
direction, decreases possibility of errors
__________ visible spots on the TLC plate with a pencil. Use a
UV lamp to see spots only visible in the UV (usually white or
lightly colored compounds). Take a digital picture of the plate
and attach it to your ELN. In a table, record the __________ and
________ of each spot. Provide one sample Rf calculation,
clearly indicating where the values came from on your TLC
plate. Correct Answers Circle
color
Rf values
__________________ the mixture to separate the extract from
the leaves. Use the 125 mL Erlenmeyer collection flask. Make
sure to use _______________ during the filtration! Pour the
spinach extract from the flask, while trying to avoid pouring all
of the spinach leaves into the filter. Keep filtering the extract
until the spinach leaf pulp left on the filter paper looks relatively
________. If it looks like some pulp went through the filter and
into your collection flask, quickly filter the extract one more
time, using a different piece of filter paper. Dispose of filter
paper containing spinach leaves in the trash can. Correct
Answers Vacuum filter
, filter paper
dry
Add ______ mL DI water to the pulpy mixture, and pour this
solution into a 50 mL flask. Then add _______________ and
___________________ to the mortar and pestle to wash out any
remaining spinach leaves into the flask. Swirl the mixture gently
for ~1 minute. Correct Answers 10
10 mL heptane
2 mL of acetone
Add a ___________ (r2 value) and ____________ Equation to
your graph. What does the r2 value represent? Correct Answers
Linear Regression
Trendline
- r2 value represents how close the data is to the linear
regression line
Add just enough anhydrous ___________ to Extract #1 to fill
the bottom tip of the test tube (about 10-15% of the extract's
total volume). Using a stirring rod, mix the contents of the test
tube. What does the anhydrous MgSO4 do? How does it interact
with the extract? What does it become? Correct Answers
MgSO4
- removes the water from extract
Choose New from the File menu. Prepare a ________ by filling
an empty cuvette with _________. Place the blank in the
spectrometer. Select Finish Calibration and OK. Why is heptane
used as the blank? Why did the spectrometer need to be
recalibrated? Correct Answers blank
_________ the outside of the cuvette with a Kimwipe and place
the blank in the spectrometer. When taking an absorption
measurement, always align the cuvette with the same face (mark
the top of the cuvette with a grease pencil) pointing toward the
detector. Why is this necessary? Correct Answers wipe
- absorption may be read incorrectly if facing the wrong
direction, decreases possibility of errors
__________ visible spots on the TLC plate with a pencil. Use a
UV lamp to see spots only visible in the UV (usually white or
lightly colored compounds). Take a digital picture of the plate
and attach it to your ELN. In a table, record the __________ and
________ of each spot. Provide one sample Rf calculation,
clearly indicating where the values came from on your TLC
plate. Correct Answers Circle
color
Rf values
__________________ the mixture to separate the extract from
the leaves. Use the 125 mL Erlenmeyer collection flask. Make
sure to use _______________ during the filtration! Pour the
spinach extract from the flask, while trying to avoid pouring all
of the spinach leaves into the filter. Keep filtering the extract
until the spinach leaf pulp left on the filter paper looks relatively
________. If it looks like some pulp went through the filter and
into your collection flask, quickly filter the extract one more
time, using a different piece of filter paper. Dispose of filter
paper containing spinach leaves in the trash can. Correct
Answers Vacuum filter
, filter paper
dry
Add ______ mL DI water to the pulpy mixture, and pour this
solution into a 50 mL flask. Then add _______________ and
___________________ to the mortar and pestle to wash out any
remaining spinach leaves into the flask. Swirl the mixture gently
for ~1 minute. Correct Answers 10
10 mL heptane
2 mL of acetone
Add a ___________ (r2 value) and ____________ Equation to
your graph. What does the r2 value represent? Correct Answers
Linear Regression
Trendline
- r2 value represents how close the data is to the linear
regression line
Add just enough anhydrous ___________ to Extract #1 to fill
the bottom tip of the test tube (about 10-15% of the extract's
total volume). Using a stirring rod, mix the contents of the test
tube. What does the anhydrous MgSO4 do? How does it interact
with the extract? What does it become? Correct Answers
MgSO4
- removes the water from extract
Choose New from the File menu. Prepare a ________ by filling
an empty cuvette with _________. Place the blank in the
spectrometer. Select Finish Calibration and OK. Why is heptane
used as the blank? Why did the spectrometer need to be
recalibrated? Correct Answers blank
