CAS CH 171 Lecture Notes - Lecture 3: Leading Zero, Significant Figures, Specific Gravity

• School: Boston University
• Department: Chemistry
• Course: CAS CH 171
• Professor: Allison Lamanna

Document Summary

Accuracy- how close you are to correct answer. Precision- how consistent your set of answers. Position of uncertainty- you are guessing the value. Between 1 and 2, and the 9 is a guess (1. 9) Between 1. 8 and 1. 9 and the 6 is a guess (1. 86) 1. 86 cm = . 0186 m leading zeroes = not significant bc you are just converting into another unit. 1. 90 cm trailing zeroes = right of decimal are significant. 120 trailing zero left of the decimal not significant unless specifically indicated. 120 [2 sf] - just as is is not sf. Decimal must contain some number of sfs. Do it all and then look at the one with the fewest and that"s the number of sfs for the answer. Ex: 2. 2 (2 sfs) x 0. 9 (1 sf) = 1. 98 m 2 1 sf. Answer must contain same number of sig figs to the right of the decimal. Not total number, but number after the decimal.