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Chemistry 1025 Environmental Science Lab Final Exam Review Questions and Answers
Chemistry 1025 Environmental Science Lab Final Exam Review Questions and Answers
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Chemistry 1025 Environmental ScienceLab Final Exam Review Questions and
Answers
A number is a significant figure if it is: - -a. a nonzero digit 4.5 g 2
122.35.m 5
b. a zero digit between nonzero digits 205 m 3
5.082 kg 4
c. a zero at the end of a decimal number 50. L 2
25.0 oC 3
d. any digit in the coefficient of a number 4.0 x 105 m 2
written in scientific notation
-A number is not significant if it is: - -a. a zero at the beginning of a decimal
number 0.0004 lb 1
0.075 m 2
b. a zero used as a placeholder in a large 850,000 2
number without a decimal point
-In regards to significant figures, in multiplication and division, the final
answer is written so it has the same number of digits as the measurement
with the fewest significant figures - -Example:
24.65 x 0.67 = 16.5155 17
four SF two SF calculator display final answer rounded to two SF
-What is meant by the "Q" value? - -Those individual values that are
farthest from the mean are candidates for deletion
(―rejection‖) from the data set. For small data sets (n < 10), a simple
method to determine
if an individual value needs to be rejected is the statistical test known as the
Q test. In this
test, a value for ―Q‖ is calculated and compared to a table of Q values that
represent a
certain percentage of confidence that the proposed rejection is valid. If the
calculated Q
value is greater than the value from the table, then the suspect value is
rejected and the
mean is recalculated. If the Q value is less than or equal to the value from
the table, then
the calculated mean is reported. ―Q‖ is defined as follows:
Q = gap / range
where the ―gap‖ is the difference between the suspect value and its nearest
neighbor and
, the ―range‖ is the difference between the questionable value and the value
furthest from
it.
-What is meant by the Average or Mean value? - -the sum of the
measurements divided by the number of measurements.
-Is the vertical axis the x or the y axis? - -y
-is the horizontal axis the x or the y axis? - -x
-the vertical axis is the ___________? - -ordinate (y)
-the horizontal axis is the ____________? - -abscissa (x)
-Name the 5 steps involved in constructing a graph - -1. select the axes.
2)Set the scales for the axes (they do not have to be the same. 3)Plot the
data. 4) Draw a curve for the best fit or straight line if that's appropriate. 5)
Title your graph.
-The formula for density is: - -mass divided by volume
-Clearly define precision and accuracy - -Accuracy is how closely the
measured values lie to the true values. Precision is how closely the measured
values lie to one another.
-Given the following five measurements, apply the Q test (90% confidence
level) and decide whether the suspect value (12.155) can be rejected.
12.036, 12.155, 12.041, 12.012, 12.025 - -Q=gap/range
gap =
range =
-After carefully measuring the mass and volume of aluminum, a student
calculates the density of aluminum to be 2.95 g/mL. According to the CRC
Handbook of Chemistry and Physics, the density of aluminum is 2.702 g/mL.
What is the percent error in the student's measured density? - -percent error
= [x-y] / y x 100
x=your measured value
y=the accepted value
-In what form do plants and trees generally absorb nitrogen? - -nitrate ion
-What process converts the nitrogen-containing ion in part a) into the
nitrogen-containing ion in part b)? - -nitrification or nitrogen fixation
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