Accuracy and Precision

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