Lab 1 Report - Gregory Chekerdjian
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Lab 1: How Do We Make Accurate and Precise Measurements REPORT FORM
Answer the following discussion questions. Support your claim using evidence, i.e. experimental
data that supports the claim. Cite specific quantitative results. Connect your evidence to your claim using reasoning that explains why your evidence supports your claim. Reasoning should be based on a scientific rule, law, principle or definition.
Question #1. Which calculation or value provides you with an indication of the accuracy of the glassware? Which piece(s)has/have the greater accuracy, the 10.00-mL graduated cylinder, 50.0-mL graduated cylinder, 50.00-mL buret, or 10.00-mL pipet? Provide an example for the calculation or value and explain using your quantitative results.
Page 1
of 4
To answer these questions, you will need to calculate the following:
mass of water for all trials,
volume of water for all trials,
mean absolute deviation for each measurement device,
percent error for each trial and
average percent error for each measurement device. Your data and these calculations will make up the quantitative results you will use
to support your answers to the report questions. It is recommended that you write
out at least one calculation and make note of your calculation results in your laboratory notebook for future reference. Laboratory material is also included in exam content, and these can be useful materials for studying for the exams. The 10ml pipet was the most accurate method as it was the closets to 10 ml and had an average of 9.98ml for all three trials. The three trials were 10.0342, 9.9888 and 9.9427 below I showed the percent error and how the average percent error was 0.34%.
Trial 1: |
10.0342
−
10.00
|
10.00
×
100
=
0.34%
Trial 2: |
9.9888
−
10.00
|
10.00
×
100
=
0.11%
Trial 3: |
9.9 427
−
10.00
|
10.00
×
100
=
0.57 %
Average: (
0.34
+
0.11
+
0.57
)
3
=
0.34 %
The device with the lowest MAD was also the 10ml Pipet which means it was the most precise as seen in the calculations below.
Average volume added: 9.9888
+
10
.
0342
+
9.9427
3
=
9.9885
mL
MAD = (
|
9.9888
−
9.9885
|
+
|
10.0342
−
9.9885
|
+
|
9.9 427
−
9.9885
|
)
3
=
0.0306
.
Question #2. Which calculation or value provides you with an indication of the precision of the glassware? Which piece(s) of glassware has/ have the greatest precision for measuring volume: the 10.00- mL graduated cylinder, 50.0-mL graduated cylinder, 50.00-mL buret or 10.00-mL pipet? Provide an example for the calculation or value and explain using your quantitative results.
Question #3. Which piece of glassware would you use if the volume of liquid needed be measured relatively quickly and did not need to be extremely precise? Explain your reasoning.
Question #4. Which of these pieces of glassware would be best to deliver a precise volume into a solution but you do not know ahead of time what that volume would be? Explain your reasoning.
Page 2
of 4
If I had to repeat this experiment and had to measure relatively quickly, I would use the 10 ml graduated cylinder. The 10ml graduated cylinder was by far the simplest to use because you just pour a little less then 10ml and then add a little more with the medicine dropper. If I had to get the most precise volume, I would have used the 10ml pipet as it was the most
accurate. Although it took a little more time to use then the others it paid off as I said in question 1 and we ended up with the lowest percent error.
Question #5. Recalculate the mean absolute deviation of the glassware using the combined data from you and the two other groups. What can you say about the difference in precision between your measurements and the combined measurements of the three groups? Has the precision changed? Explain using your quantitative results.
Question #6. Recalculate the percent error of the glassware using the combined data from you and the two other groups. What can you say about the difference in accuracy between your
measurements and the combined measurements of the three groups? Has the accuracy changed? Explain using your quantitative results.
Page 3
of 4
The Average MAD was better than my teams only which shows that the 10ml pipet was precise.
MAD Group 2 = (
|
9.9503
−
9.9445
|
+
|
9.9378
−
9.9 445
|
+
|
9.9455
−
9.9445
|
)
3
=
0.0045
MAD Group 3 = (
|
9.93
−
9.9567
|
+
|
9.98
−
9.9567
|
+
|
9.96
−
9.9567
|
)
3
=
0.0093
Average MAD = ¿
(
0.0306
+
0.0045
(
group
2
MAD
)+
0.0093
(
group
3
MAD
))
3
=
0.0148
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Question #7. If you went back in time to repeat the measurement for the Hubble Space Telescope, what measure(s) would you use to ensure the correct thickness of the mirror? Explain your reasoning.
Page 4
of 4
Using the other groups data, I got a percent error of 0.38%
0.34
+
0.55
(
group
1
)+
0.27
(
group
2
)
3
=
0.38%
After calculating the other two groups measurements we can still see how the 10ml pipet was very accurate and its average percent error for all 9 trials was only 0.38% which is very reasonable considering 4 different people worked to get these values.
If I could go back in time to repeat the measurements for the Hubble Space Telescope, I would make sure its accurate and precise. I would also double check everything and do several tries and take the average of the three trials.
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Read the case study and use your knowledge of the scientific method to identify the observation, hypothesis, experiment, and conclusion.
Our English springer spaniels like our neighbors’ children and could play with them all day. We thought our dogs will never dislike any children they will ever meet. Last month when we took our dogs on a trip, we met some German tourists in a park. The dogs loved playing with the foreign family’s children. Our English springer spaniels like all children.
Match the words to the appropriate blanks in the sentences. Make certain each sentence is complete before submitting your answer.
View Available Hint(s)for Part B
ResetHelp
returned
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Allowing the dogs to play with the German family's children is the hypothesis.target 2 of 4
"Our English springer spaniels like all children" is our…
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Part B
Gather all of your pennies dated before 1982. Then follow the steps to complete the table. Include units as necessary.
Record the number of pennies dated before 1982.
Weigh (as a group) the pennies dated before 1982. Record the total mass. If you’re unfamiliar with using an electronic balance, watch this video before continuing.
Calculate and record the average mass of a single penny. If you need help with the calculation, visit the averaging data section of the math review.
number of pennies: 8
combined mass of the pennies (g): 49.2
average mass of a penny (g): 5.525
Part C
Now gather all of your pennies dated after 1982. Complete the table for the post-1982 pennies using the same steps from part B.
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combined mass of the pennies (g): 51.7
average mass of a penny (g): 5.744
Part D In parts B and C, you measured the average mass of each group of pennies. Now you’ll measure their volume. (For this part, assume that the pennies dated before and after…
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Part B
Gather all of your pennies dated before 1982. Then follow the steps to complete the table. Include units as necessary.
Record the number of pennies dated before 1982.
Weigh (as a group) the pennies dated before 1982. Record the total mass. If you’re unfamiliar with using an electronic balance, watch this video before continuing.
Calculate and record the average mass of a single penny. If you need help with the calculation, visit the averaging data section of the math review.
number of pennies: 8
combined mass of the pennies (g): 49.2
average mass of a penny (g): 5.525
Part C
Now gather all of your pennies dated after 1982. Complete the table for the post-1982 pennies using the same steps from part B.
number of pennies: 9
combined mass of the pennies (g): 51.7
average mass of a penny (g): 5.744
Part D In parts B and C, you measured the average mass of each group of pennies. Now you’ll measure their volume. (For this part, assume that the pennies dated before and after…
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Which statement is true?
Question 12 options:
Precision is measured by standard deviation.
Precision is measured by error or relative error.
Accuracy is measured by the standard deviation.
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Part 3: Calculate density of a metal an unknown metal.
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Mass measurement
7.1 g
Volume of water
measurement. There's
only one measurement
here – the larger image
is for magnification
only.
-20
15 m
Volume of water and
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There's only one
measurement here – the
larger image is for
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15
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Place chemicals directly on the balance pan.
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Report Sheet-Lab 2
A.2 Area
Your measurements
Length =
Width =
Area =
(Show calculations.)
Why could two students obtain different values for the calculated areas of the same rectangle?
A.3 Volume of a solid by direct measurement
Shape of solid
Formula for volume of solid
18
Height
Width
Another student's
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Volume of the solid
(Show calculations of volume including the units.)
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Page 3 of 3
482 words
区
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mL
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Volume
Calculations
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Stone 2
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土
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