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? Schedule 1.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

Metrics Kilo Hecta Deca Base Unit Deci Centi Milli g, L, m Convert the following using the metric system: – A. 45 mL to dL – B. 200 g to kg – C 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 cm 3 to m 3 20 kg/m 3 to g/cm 3

Scientific Notation Convert to Scientific Notation – 0.25 – – – 5050

Convert to Standard Notation 1 x x x 10 2

Significant Figures Counting Sig Figs – Count all numbers EXCEPT: Leading zeros Trailing zeros without a decimal point -- 2,500

, Significant Figures Counting Sig Fig Examples , sig figs 3 sig figs 2 sig figs

Identify the # of Significant Figures

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/cm 3 )(23.3cm 3 ) = g 324 g 4 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 mL mL 7.85 mL 224 g g 354 g  7.9 mL  354 g 3.75 mL mL 7.85 mL 224 g g 354 g

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

C. Derived Units Combination of base units. 1 cm 3 = 1 mL 1 dm 3 = 1 L Density - mass per unit volume (g/cm 3 ) D = MVMV 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: g = 1 lb cm = 1 in 3.16 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 = V final - V inital (Use any time you do water displacement) Volume of a sphere: (Question 12) V= 4/3 ∏r 3 Advice Show your math work on a separate sheet of paper with UNITS and CIRCLE your final answer. Remember your SIG FIGS!!