UNA Chem 101 Lab 6 Exam Graded A+
A coffee drink is made by passing hot water through ground coffee beans in a coffee
maker. Is this drink a mixture? What separation technique was used in the preparation
of the drink? - ANSWER-Yes. Extraction occurs.
A sample of French fried potatoes weighing 150g was extracted with the volatile organic
solvent hexane. The recovered cooking oil weighed 12.3g. What methods from this
experiment could be used to separate and isolate the cooking oil after the extraction?
What was the percent oil in the potatoes? - ANSWER-Decantation
(12.3/150)*100 = 8.20% oil in the potatoes
Both naphthalene and para-dichlorobenzene are effective moth repellents. What
property of these chemical allow them to be used in mothballs for the protection of
wollen clothing? - ANSWER-These chemicalms undergo sublimation. The gas created
is poisonous to moths but doesn't harm clothes.
Both sublimation and evaporation bring material into the vapor phase. How do the two
methods of separation differ? - ANSWER-Sublimation goes from solid directly to gas.
Evaporation goes from liquid to gas.
Do the five methods described in the background involve physical changes or chemical
changes of matter? - ANSWER-Physical: the chemical identity of the substance stays
the same
In step 14 the sand was not completely free from water when the weight was reported.
How does this affect the percent composition of the sand in the mixture? - ANSWER-It
is increased.
In your experiment did you recover 100% of the original mixture? What was your
percent recovery? - ANSWER-No, 91.58%
Snow in the winter can slowly disappear even when the temperature is freezing. How do
you account for this observation? - ANSWER-Air temperature and ground temperature
are not the same. Sublimation occurs.
The weight of Naphthalene was obtained by weighing the collected solid. Was this an
accurate weight of the naphthalene present in the original sample? - ANSWER-No, the
experiment allows for the loss of come caffeine.
