Thursday!!!!! 9/1/11

1
Thursday!!!!!9/1/11
PAP Chemistry

• Bell Ringer

• Schedule

1. Bell Ringer
2. Numbers in Science Lab
3. Who Are You??

• Get out your Numbers in Science lab, your notes
  from yesterday, and complete your lab. Turn it
  in to your tray when you are finished.
• What have you heard about a mutant strain of the
  Bird Flu?

HOMEWORK Metric, Sig Fig, Dimensional Anaylysis
quiz tomorrow!!
I CANaccurately perform measurements in the lab
utilizing sig figs
Teachers open the door, but you must enter by
yourself ?
2
MetricsKilo Hecta Deca Base Unit Deci
Centi Milli1000 100 10 g, L, m
.1 .01 .001

• Convert the following using the metric system
• A. 45 mL to dL
• B. 200 g to kg
• C. 4200 mm to m

3
Dimensional AnalysisFactor Label Method

• 5 hrs to sec
• 4 miles to in 5,280 ft. 1mile 1 ft 12
  in.
• 5 moles to Liters 1 mole 22.4 liters
• 50 cm3 to m3
• 20 kg/m3 to g/cm3

4
Scientific Notation

• Convert to Scientific Notation
• 0.25
• 0.025
• 0.0025
• 5050

5
Convert to Standard Notation

• 1 x 104
• 1 x 10-4
• 2.2x 102

6
Significant Figures

• Counting Sig Figs
• Count all numbers EXCEPT
• Leading zeros -- 0.0025
• Trailing zeros without a decimal point -- 2,500

7
Significant Figures
Counting Sig Fig Examples
1. 23.50
1. 23.50
4 sig figs
3 sig figs
2. 402
2. 402
3. 5,280
3. 5,280
3 sig figs
2 sig figs
4. 0.080
4. 0.080
8
Identify the of Significant Figures

• 0.02
• 0.020
• 501
• 501.0
• 5000
• 5.000
• 0.00470
• 0.47000

9
Significant Figures

• Calculating with Sig Figs
• Calculating with Sig Figs (cont)
• Exact Numbers do not limit the of sig figs in
  the answer.
• Counting numbers 12 students
• Exact conversions 1 m 100 cm
• 1 in any conversion 1 in 2.54 cm
• Multiply/Divide - The with the fewest sig figs
  determines the of sig figs in the answer.

(13.91g/cm3)(23.3cm3) 324.103g
4 SF
3 SF
324 g
10
Significant Figures

• Calculating with Sig Figs (cont)
• Add/Subtract - The with the lowest decimal
  value determines the place of the last sig fig in
  the answer.

224 g 130 g 354 g
224 g 130 g 354 g
3.75 mL 4.1 mL 7.85 mL
3.75 mL 4.1 mL 7.85 mL
? 354 g
? 7.9 mL
11
Calculating error

• Experimental 1.24 g
• Accepted 9.98 g
• error ?

12
C. Derived Units

• Combination of base units.
• 1 cm3 1 mL 1 dm3 1 L
• Density - mass per unit volume (g/cm3)

13
Significant Figures

• Indicate accuracy of a measurement as will as the
  measuring capacity of the instrument used.
• Recording Sig Figs
• Sig figs in a measurement include the known
  digits plus a final estimated digit

2.35 cm
14
Numbers in Science

• Lab Tips

• Advice

• Conversions
• 454 g 1 lb.
• 2.54 cm 1 in
• 16 oz 1 lb.
• Density Mass/Volume
• Volume length x width x height (Use any time
  you use a ruler)
• Circumference C ?d (Question 10)
• Diameter d 2r (Question 11)
• V Vfinal- Vinital (Use any time you do water
  displacement)
• Volume of a sphere (Question 12)
• V 4/3 ?r3

• Show your math work on a separate sheet of paper
  with UNITS and CIRCLE your final answer.
• Remember your SIG FIGS!!