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Scientific Measurement Ch. 3. Why are precise measurements and calculations essential to the study of chemistry?. (3.1) Measurements. Quantity that has a number and unit. Accuracy and Precision. How close a measurement comes to the actual value of what is being measured
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Scientific MeasurementCh. 3 Why are precise measurements and calculations essential to the study of chemistry?
(3.1) Measurements • Quantity that has a number and unit
Accuracy and Precision • How close a measurement comes to the actual value of what is being measured • How close a series of measurements are to one another
Significant Figures KNOW the rules for determining sig figs Pgs. 66-67
Measured values having digits that are known with certainty and a final digit that is estimated
1) ALL non-zero numbers are ALWAYS significant. 2) ALL zeroes between non-zero numbers are ALWAYS significant. 3) ALL zeroes which are to the right of the decimal point AND at the end of the number are ALWAYS significant. 4) ALL zeroes to the left of a decimal point and in front of nonzero digits are not significant.
48,923 3.967 500.06 0.0004 8.1000 501.040 3,000,000 10.0
Sig Figs in Calculations Many-Places Rule Mult./Div. – how many sig figs in least Plus/Minus – no. of placesin least
305.1 x 35 5400 ÷ 9.89 305.7 + 35.035 5403 - 139.89
Percent Error Error = Experimental value - Theoretical Percent error =
Scientific Notation • 6.02 x 1023 (see pg. R56 of text for more practice)