Friday Sept 7th

1
Friday Sept 7th

• Grab a calculator
• Warm up for today
• Finish problems 6-10 on the back of the
  dimensional analysis paper from yesterday

2
Significant Figure ReviewGoal Students will
know how to round all mathematical answers to be
as specific as the given amount
3
Rules for Significant Figures

• Nonzero numbers are ALWAYS significant.
• 1287 g
• 78,483 cm
• 58 mL
• 638 mol

4 Sig Figs
5 Sig Figs
2 Sig Figs
3 Sig Figs
4
Rules for Significant Figures

• Zeros in-between nonzero numbers are ALL
  significant.
• 101 mol
• 20,375 cd
• 1001 J
• 908 s

3 Sig Figs
5 Sig Figs
4 Sig Figs
3 Sig Figs
5
Rules for Significant Figures

• Zeros after nonzero numbers (trailing zeros) WITH
  A DECIMAL PRESENT are significant
• 6.0 mg
• 678.10 Kg
• 80.0 m
• 12.00 mL

2 Sig Figs
5 Sig Figs
3 Sig Figs
4 Sig Figs
6
Rules for Significant Figures

• Zeros in front of nonzero digits (preceding
  zeros) are not significant. They are called place
  holders.
• 0.78 Kg
• 0.0309 cd
• 290 amp
• 300 s

2 Sig Figs
3 Sig Figs
2 Sig Figs
1 Sig Figs
7
Rules for Significant Figures

• Counting numbers and defined constants have an
  infinite number of significant figures.
• 1 dozen 12
• 78 pencils
• 32 books
• 1 pair 2

Infinite Number of Sig Figs
Infinite Number of Sig Figs
Infinite Number of Sig Figs
Infinite Number of Sig Figs
8
Zeros that are significant.
3 Sig Figs

• 202 cm
• 510002 L
• 144.0 kg
• 670.00 cd

6 Sig Figs
4 Sig Figs
5 Sig Figs
9
Zeros that are NOT significant, PLACE HOLDERS.
1 Sig Figs

• 50 g
• 0.0072 m
• 0.0321 J
• 9000 L

2 Sig Figs
3 Sig Figs
1 Sig Figs
10
Zeros that are significant (called Trailing) and
zeros that are not significant (call Place
Holder).
4 Sig Figs

• 80020 s
• 0.00401 kg
• 0.03020 Amp
• 10230 L

3 Sig Figs
4 Sig Figs
4 Sig Figs
11
Making Calculations with Significant Digits

• Multiplying and Dividing
• The final answer is rounded to have the same
  number of significant figures as the measurement
  with the least number of significant figures.
• 755 cm x 33 cm 24915
• 92 m x 20 m 1840

25000 cm2
2000 m2
12
0.45g

• 0.894 g / 2.0 g 0.447 g
• 40.0 x 3.8 152
• 203 x 4589 931567
• 10259 / 789 13.00253485
• 96.0 / 75.0 1.25
• 101 x 0.020 2.02

150
932000
13.0
1.25
2.0
13
Making Calculations with Significant Digits

• Adding and Subtracting
• The final answer is rounded so that it has the
  same number of digits past the decimal as the
  measurement with the least number of digits past
  the decimal

215.9
14
733.03
56.98
15
13