Errors in Measurements Class measurements for the density of gold (in g/mL) Group 117.8Group Group 218.0Group Group 317.9Group 618.0

Errors in Measurements Precision – Measurements close to one another. Group 117.8Group Group 218.0Group Group 317.9Group Class measurements are precise….

Errors in Measurements Accuracy – Measurements close to correct value. Group 117.8Group Group 218.0Group Group 317.9Group The actual value for the density of gold is 19.3 g/mL. So the class is not accurate…

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Errors in Measurements Check your accuracy by calculating your Percent Error

Errors in Measurements Accepted – What the “true” value is Measured – What you found in the experiment.

Errors in Measurements What is the percent error for the class data then? Percent Error = 7.25% Class Avg.

Significant Digits What is the reading for these two volumes? 33.5 mL 30 mL 30.0 mL

[ Most Accurate Cylinder? 65 mL vs mL

Significant Digits Gas Station Analogy – Gas $ gal = $ gal = $ gal = $ gal = $45.00

Significant Digits Numbers that are “given” to you must be checked for their accuracy as well vs vs Atlantic-Pacific Rule – Pg. 26

All non-zero digits are significant Zeros depend on the decimal point significant digits

significant digits

significant digits

6.02 x significant digits

Significant Digits Multiply / Divide Use the smaller number of significant digits for the answer. [

Significant Digits Add / Subtract Line up the decimal places then round answer. [