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Weigh approximately 0.50 grams of a snack food.
If you get too much do not eat the excess!
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Carefully transfer all of the weighed snack food
to a mortar and crush the sample using the pestle.
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Add about 3 mL of petroleum ether to the mortar
containing the crushed snack food and grind the mixture
using the pestle. Allow the misture to stand while you
prepare the filter apparatus.
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Obtain a piece of circular filter paper.
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Fold in half.
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Then into quarters.
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Open and set into a plastic filter funnel.
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Set the filter funnel containing the filter paper
into a wire triangle which is resting on a ring clamp on
a rind stand.
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Obtain a clean 18 x 150 mm test tube and a 100 mL
beaker. Determine the mass of both using the analytical
balance and record the mass on the Results page in your
laboratory manual.
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Set the test tube beneath the filter funnel so
the filterate drains into the test tube. transfer all of
the snack food/petroleum ether mixture into the filter
paper. You may need a spatula to help transfer all of the
solid. Wash the mortar with 3 mL amounts of the ether to
help transfer all of the mixture. The mortar may require
several washings to transfer all of the mixture.
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Take the test tube and beaker to the fume hood
with the hot plate. Set the beaker on the hot plate and
allow the petroleum ether to evaporate. This may take up
to 15 minutes. Periodically check the sample. After the
ether has evaporated remove the beaker and test tube from
the hot plate and allow the sample to cool.
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Re-weight the test tube and beaker to obtain the
mass of fat obtained from the snack food. Calculate the %
fat as described in the laboratory manual. Check with
others in the laboratory to compare results.
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