Accuracy and Precision
Essay by review • March 2, 2011 • Essay • 765 Words (4 Pages) • 1,930 Views
Experiment #4
Weighing and Volumetric Techniques вЂ" Accuracy and Precision
Abstract
The purpose of this experiment is to become familiar with proper techniques for using the analytic balances, graduated cylinder, burette and pipette and determine which is more accurate and/or precise. In this experiment, the burette and pipette were more exact than the graduated cylinder and the analytic balance gave a very accurate and precise answer.
Results / Report
1) Weighing Copper
Copper sample #: 1
Balance #: 14
Temperature: 22.8EC
Weighing Attempt # Mass of Copper Sample (g)
1 3.1234
2 3.1233
3 3.1235
4 3.1232
Average Mass
= (3.1234g + 3.1233g + 3.1235g + 3.1232g) Ð"* 4
=3.1234g
Standard Deviation
( - ) ( - )
3.1234 0 0
3.1233 -
3.1235
3.1232 -
ОЈ =
Or 0.0001
2) Burette Readings
a) Graduated Cylinder b) Pipette
Initial Volume (mL) 44.72 44.91
Actual amount added (mL) Actual amount added (mL)
1st 34.81 9.91 1st 34.98 9.93
2nd 24.90 9.91 2nd 25.00 9.98
3rd 15.05 9.85 3rd 15.08 9.92
Graduated Cylinder average
( 9.91Ð'±0.01 mL + 9.91Ð'±0.01 mL + 9.85Ð'±0.01 mL ) Ð"* 3
= 9.89Ð'±0.03 mL
Pipette average
(9.93Ð'±0.01 mL + 9.98Ð'±0.01 mL + 9.92Ð'±0.01 mL) Ð"* 3
= 9.94Ð'±0.03 mL
3)
Device Initial Mass (g) Final Mass (g) Resulting Water Mass (g)
Graduated Cylinder 21.5291 31.2987 9.7696
Pipette 20.5674 30.4927 9.9253
Burette 21.2779 31.3261 10.0482
TRUE VALUES
Graduated Cylinder
Density @ 24.3EC = 0.997225g/mL
Volume = Mass Ð"* Density
= 9.7696g Ð"* 0.997225g/mL
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