# Accuracy and Precision

Weighing and Volumetric Techniques – 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)

13.1234

23.1233

33.1235

43.1232

Average Mass

= (3.1234g + 3.1233g + 3.1235g + 3.1232g) ÷ 4

=3.1234g

Standard Deviation

( - )( - )

3.123400

3.1233-

3.1235

3.1232-

Σ =

Or 0.0001

2) Burette Readings

a) Graduated Cylinder b) Pipette Initial Volume (mL)44.7244.91

Actual amount added (mL)Actual amount added (mL)

1st34.819.911st34.989.93

2nd24.909.912nd25.009.98

3rd15.059.853rd15.089.92

Graduated Cylinder average

( 9.91±0.01 mL + 9.91±0.01 mL + 9.85±0.01 mL ) ÷ 3

= 9.89±0.03 mL

Pipette average

(9.93±0.01 mL + 9.98±0.01 mL + 9.92±0.01 mL) ÷ 3

= 9.94±0.03 mL

3)

Device Initial Mass (g)Final Mass (g)Resulting Water Mass (g) Graduated Cylinder21.529131.29879.7696

Pipette20.567430.49279.9253

Burette21.277931.326110.0482

TRUE VALUES

Graduated Cylinder

Density @ 24.3EC = 0.997225g/mL

Volume = Mass ÷ Density

= 9.7696g ÷ 0.997225g/mL

= 9.7968 mL

Pipette

Density @ 23.3EC = 0.997470g/mL

Volume = 9.9253g ÷ 0.997470g/mL

= 9.9505 mL

Burette

Density @ 23.4EC = 0.997446g/mL

Volume = 10.0482g ÷ 0.997446g/mL

=...

Please join StudyMode to read the full document