Pre IB Topic 1: Measurement & matter
Significant figures in measurements The digits in a measurement up to and including the first uncertain digit are the significant figures. Measurement # Significant figures EX: 62 2 0.0452 4.5 2 4.50 3 4.505 4
Significant figures in measurements • http://getyourwebsitehere.com/jswb/rttest01.html
Significant figures in measurements • http://www.teacherled.com/resources/dials/dialsload.html
Significant figures in calculations • Multiply & divide • Answer should be quoted with the same number of significant figures as the least precise data. • Add & subtract • Answer should be quoted with the same number of decimal places as the least precise value.
Percent uncertainty Absolute uncertainty_ Measured value Compares: uncertainty to the measured value X 100%
Percent error Accepted value - Experimental value_ Accepted value Compares: measured value to published values X 100%
Let’s Try It! • Record the volumes of water in the graduated cylinders with uncertainty • “Pull” water into the pipet using the plastic filler, record the volume. Dispense the water into a graduated cylinder, record the volume on the pipet. Subtract the final volume from the initial volume on the pipet. Compare to the volume in the graduated cylinder.