Thursday!!!!!9/1/11

Bell Ringer• 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?

Schedule1. Bell Ringer

2. Numbers in Science Lab

3. Who Are You??

HOMEWORK: Metric, Sig Fig, Dimensional Anaylysis quiz tomorrow!!

PAP Chemistry

Teachers open the door, but you must enter by yourself

I CAN……accurately perform measurements in the lab utilizing sig figs

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

Dimensional Analysis“Factor 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

Scientific Notation

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

Convert to Standard Notation

• 1 x 104

• 1 x 10-4

• 2.2x 102

Significant Figures

• Counting Sig Figs

– Count all numbers EXCEPT:

• Leading zeros -- 0.0025

• Trailing zeros without a decimal point -- 2,500

4. 0.080

3. 5,280

2. 402

1. 23.50

Significant Figures

Counting Sig Fig Examples

1. 23.50

2. 402

3. 5,280

4. 0.080

4 sig figs

3 sig figs

3 sig figs

2 sig figs

Identify the # of Significant Figures

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

Significant Figures• Calculating with Sig Figs• Calculating with Sig Figs (con’t)

– 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

324 g

4 SF 3 SF 3 SF

C. Johannesson

Significant Figures

• Calculating with Sig Figs (con’t)– Add/Subtract - The # with the lowest decimal value

determines the place of the last sig fig in the answer.

3.75 mL

+ 4.1 mL

7.85 mL

224 g

+ 130 g

354 g 7.9 mL 354 g

3.75 mL

+ 4.1 mL

7.85 mL

224 g

+ 130 g

354 g

Calculating % error

• Experimental = 1.24 g• Accepted = 9.98 g • % error =?

100literature

literaturealexperimenterror %

C. Derived Units

• Combination of base units.1 cm3 = 1 mL 1 dm3 = 1 L

• Density - mass per unit volume (g/cm3)

D = MV D

M

V

C. Johannesson

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

Numbers in Science Lab Tips

• Conversions:1. 454 g = 1 lb.2. 2.54 cm = 1 in3. 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

Advice• Show your math

work on a separate sheet of paper with UNITS and CIRCLE your final answer.

• Remember your SIG FIGS!!