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Chapter 3

Chemistry

Significant Figures & Conversion Factors

a journey into the inner workings of matter!


chemistry syllabus


Chapter 4

Judith S. de Nuño

jdenuno@mhs-la.org

WebSites

http://members.home.net/jdenuno

Science at Marymount
Office Hours

Daily at Lunch in the

Science Patio

Cyber Office Hours

AIM: teachsci23

SIGNIFICANT FIGURES

1.  All non-zeros are significant

2.  All captive zeros are significant

3.  All trailing zeros AFTER a decimal point are significant

4.  Leading zeros are NEVER significant

5.  Multiplication--Division:

  • the number of significant digits in the result is the same as that in thequantity with the smallest number of significant figures

6.  Addition-Subtraction:

  • the number of significant digits in the result is the same number of decimal places as in the measured quantity with the smaller number of decimal places

7.  Rounding:  use normal rounding rules

8.  Conversion factors: 

  • these are NOT measured quantities and are therefore NOT used to determine number of significant figures in answer
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BASE UNITS:  METRIC SYSTEM

length
meter
m
distance between 2 points
mass
gram
g
amount of matter
temperature
Kelvin
K
heat content or direction of heat flow

 
Celsius
C
Fahrenheit
F

0 K = 273oC            

absolute zero

TK = TC + 273                                             

TF = 1.8TC + 32         
Oo C or 32o F = freezing H2O
100oC or 212oF = boiling H20
time
second
s
period between events
amount of substance

mole

mol
1 mole = 6.02 x 1023 particles
(dozen
doz
1 dozen = 12 particles)
DERIVED UNITS:  METRIC SYSTEM
volume liter L amount of space
pressure pascal Pa force per unit area
atmosphere atm

1 kPa = 103 atm

1 atm = 760 torr = 760 mm Hg
torr torr
mm Hg mm Hg

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Animated Graphics Courtesy of
Jo's World