gonzales (pag757) – Postlab 2 – Lyon – (52635)
1
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printout
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have
7
questions.
Multiplechoice questions may continue on
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before answering.
This postlab 2 assignment is due by 8AM
on your next lecture day. The questions cover
experiment 2.
001
10.0 points
Using the Qtest, determine whether there is
an outlier in the following data set: 0.8543,
0.8614, 0.8573, 0.8600, 0.8419, 0.8607, and
0.8599.
Discard the outlier if there is one,
and then calculate the average and standard
deviation to the correct number of significant
figures. How would you report your results?
1.
0.857
±
0.003
2.
0.8565
±
0.00266
3.
0.859
±
0.003
correct
4.
0.85568
±
0.00266
Explanation:
0.8419 is separated from the other values,
and its nearest neighbor is 0.8543. Calculat
ing Q according to the formula in Appendix
1 gives 0.66.
There are 7 data points, so
n=7.
Since Q
>
0.51 from the Qtable, the
0.8419 data point should be thrown out. The
average of the remaining points is 0.85893.
The standard deviation of those data points
is 0.00266. Round the standard deviation to
one significant digit (0.003) and round the
average to that same decimal place (the thou
sandths place).
002
(part 1 of 2) 10.0 points
Barium chloride, BaCl
2
, is soluble in water
but is not reactive towards 3.0 M nitric acid.
Barium sulfate, BaSO
4
, is not soluble in wa
ter and does not react with 3.0 M nitric acid.
Barium phosphate, Ba
3
(PO
4
)
2
, is reactive to
wards 3.0 M nitric acid but is not soluble in
water.
a) Suppose you have a solid mixture of
barium sulfate and barium phosphate. Which
of the following schemes would recover barium
sulfate as pure solid out of the mixture?
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 Spring '10
 Lyon
 Barium, sulfate, barium chloride, barium sulfate

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