1 / 14

iChem Math: Significant Figures

iChem Math: Significant Figures. Significant Figures. Measure of precision Two issues: how to create sig figs in the lab how to interpret sig figs when already written. . Creating Sig Figs in the Lab. Record all digits known with certainty + 1 estimated digit.

debra
Download Presentation

iChem Math: Significant Figures

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. iChemMath: Significant Figures

  2. Significant Figures • Measure of precision • Two issues: • how to create sig figs in the lab • how to interpret sig figs when already written.

  3. Creating Sig Figs in the Lab • Record all digits known with certainty + 1 estimated digit.

  4. Rules for Interpreting Sig Figs • Rule 1: All non-zero digits are significant • “476” has 3 sig figs • “12345.6789” has 9 sig figs

  5. Rule 2: Zeros between nonzero digits are significant • 407 = 3 sig figs

  6. Rule 3: In a number with a decimal, all zeros to right of last nonzero are significant • 1600. = 4 sig figs • 152.000 = 6 sig figs

  7. Rule 4: In a number without a decimal, Zeros to the right of the last nonzero are not significant 720 = 2 Sig figs

  8. Rule 5: Zeros before all nonzero digits are not significant • 0.0072 = 2 Sig figs

  9. # of Sig Figs • 14.03 • 4 significant figures • 16 000 000 • 2 significant figures • 0.00107 • 3 significant figures • 20. • 2 significant figures

  10. Caution! • Calculators rarely use significant figures! • So you must round your answer to show the correct # of significant figures

  11. Rounding Rules • If number to the right of the last significant figure is: • Greater than or exactly equal to 5, round up • Less than exactly 5,truncate

  12. Example • Assume you have only 3 significant figures but your calculator shows: • 46.17, round to 46.2 • 46.11, round to 46.1 • 46.451, round to 46.5

  13. Add/Subtraction • Answer has same number of digits to right of decimal as the number with the fewest digits to right of decimal • 25.1 + 2.621 = 27.7 • 27 + 3.75 = 30.75 = 31

  14. Multiplication/Division • Round answer to the same # of significant figures as the measurement with the least # of significant figures • 2.0 x 132 = 260 • 87.65/2.07 = 42.3

More Related