Measurements Every measurements has UNITS Every measurement has uncertainty

Accuracy and precision How close a measurement is to the accepted value How close a series of measurements are close to one another. The closer the measurements are to one another, the more precise it is.

Accuracy and Precision

Significant figures are used to indicate the precision of a measured number or sets of numbers Measurements are made one place beyond where the measuring device is marked. In any measurement, the digit furthest to the right is estimated For example, a ruler marked to the nearest tenth of a centimeter can be read to the hundredths place by estimating how far between the lines the measurement falls.

Estimate +0.1/-0.1 By estimating the last digit, our measurements are not precise, they have an estimated error of +,-0.1 When you are measuring small quantities, you need to use equipment that is more precise to avoid a greater potential for error 2.35cm

Sig Fig Rules ALL NON ZERO DIGITS ARE SIGNIFICANT TRAILING ZEROS ARE NOT SIGNIFICANT 30,000m 3 x 104 m 1 sig fig 300m 30m 3m

Sig Fig Rules SANDWICHED ZEROS ARE SIGNIFICANT 303 yrs 3 sig figs 3104 lbs 5080 g

Sig Fig Rules LEADING ZEROS ARE NOT SIGNIFICANT 0.008m 8 x 10-3 1 sig fig 0.3cm 0.00343cm 0.006503 mm 0.08010cm

Calculations and reporting the correct number of sig figs ADDITION AND SUBSTRACTION Look at the decimal places and your report your answer with the least 35.23g + 23.1g 58.33g → 58.3g Significant to the 0.1 place

Calculations and reporting the correct number of sig figs MULTIPLICATION AND DIVISION Report you answer with the least amount of significant digits used in your calculation 0.2451g x 3.51g x 33.900g=29.164203 4 3 5 Your answer can only be reported with 3 sig figs → 29.2 g

Practice How many sig figs are in the following numbers: 9.03 x 103 mm 5051ft 0.0033 48,600 gal

Practice Write the answer in scientific notation and with the correct number of sig figs: 2.70 g x 0.050g x 8.09g = 8540 / 2.00 = 100 x 340= 50.0 / 80=