Ch 2 p1 Notes Chapter 2 Notes, Chemistry Notes PDF

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Chapter 1-3 Chemistry Notes, Chemistry Notes...

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Ch. 2 Measurements WS 1

Making observation is a key part of scientific process • Qualitative • Quantitative

Measurements • Collection of quantitative data • Always 2 parts, a number and a unit • Measured numbers always accompanied by an error or uncertainty limitations in the techniques every digit is certain except the last, which is estimated.

The greater the precision of the measurement, the greater the number of significant figures. ! Report the number of digits, or significant figures so that it does not appear to be more accurate than the equipment used to make the measurement allows. Rules for counting significant figures

Ch. 2 Measurements • All nonzero digits are significant. • Zeros within a number are always significant • Leading Zeros are not significantTrailing Zeros are only significant after a decimal point Exact numbers defined numbers or result from a count Practice How many significant figures are in each of the following? 0.0035 1.080 2371 cm 2.97 x105 1 dozen = 12 100.00 100,000 Scientific Notation 2345

23450

0.00002345

0.0000234500 Significant Figures in Calculation When numbers are used in a calculation, the result is rounded to reflect the significant figures of the data.

Ch. 2 Measurements Multiplication and Division Rule: The result of multiplication or division carries the same number of significant figures as the factor with the fewest significant figures.

Addition and Subtraction Rule: In addition or subtraction calculations, the result carries the same number of decimal places as the quantity carrying the fewest decimal places.

Rounding Calculations Involving Both Multiplication/Division and Addition/ Subtraction 3.489 × (5.67 – 2.3) 5.67 – 2.3 = 3.37 3.489 × 3.37 = 11.758 = 12 WS 1 p 46 # 39- 67 odd...