Scientific Measurement SWBAT: Use scientific notation to show large & small numbers Describe the difference in Accuracy and Precision

Using & Expressing Measurements  Measurement – a quantity that has both a number and a unit  Scientific Notation – an expression of numbers in the form of m x 10 n  m is equal or grater than 1 and less than 10  n is an integer  6,300,000 =  = 6.3 x x 10 -6

White Board Practice  Problem  6,234,000,000   15,010,000  1,000,000,000,000    987,600  Answer  x 10 9  x  x 10 7  1.0 x  6.7 x  3.02 x  x 10 5

Accuracy, Precision & Error  Accuracy – a measure of how close a measurement comes to the actual or true value of whatever is measured  Precision – a measure of how close a series of measurements are to one another

White Board Practice  Three students make multiple determinations of the volume of a liquid, each using a different graduated cylinder. The correct volume of the liquid had been previously determined to be mL. Describe the accuracy and precision of each student’s measurements. Volume of Liquid (mL) TrialElmerConstanceHenrietta Elmer: Neither Constance: Precise Henrietta: Accurate & Precise

Determining Error  Accepted Value – correct value based on reliable references  Experimental Value – value measured in the lab  Percent Error – the accepted value minus the experimental error divided by the accepted value, multiplied by 100

White Board Practice  The correct volume of the liquid had been previously determined to be mL.  Calculate the error using Elmer’s data from Trial – = 2.2 = X 100 = 2.55% Volume of Liquid (mL) TrialElmer

White Board Practice  The correct volume of the liquid had been previously determined to be mL.  Calculate the percent error using Henrietta’s data from Trial 3. Volume of Liquid (mL) Trial Henrietta – = = X 100 = 0.03%