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Bell Work:. Please get a text book and read the following pages silently; page 32-33. Everyone should be quiet at this time. Measurements/Calculations. Analyzing Data. Objectives:. Define SI Base Units Explain how adding a prefix changes a unit Convert between Metric Units
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Bell Work: • Please get a text book and read the following pages silently; page 32-33. • Everyone should be quiet at this time.
Measurements/Calculations Analyzing Data
Objectives: • Define SI Base Units • Explain how adding a prefix changes a unit • Convert between Metric Units • Determine Accuracy/Precision • Determine Significant Figures. • Calculate Significant Figures.
Why do chemists use SI units(do not copy this question)? Chemists use an internationally recognized system of units to communicate their findings.
What are SI Units? • Systeme Internationale d’Unites (SI) is an internationally agreed upon system of measurements.
Metric Conversions: Problem Solving • 1000gram = _______ kilograms 1 • 25 milliliters = ______ liters .025 • 35 hectograms = ______ centigrams 350000 • 409 meters = ____ decimeters 4090
What are Accuracy & Precision? • Accuracy – how close the measurement is to the true or actual value. Example: Actual Value = 2.50 Which one of these values is accurate? 2.49, 2.30, 2.31, 2.32 • Precision – the exactness of measurement
What is a Significant Figure? • Significant figure – all the digits know plus one estimated or uncertain number.
NON-ZERO NUMBERS ARE ALWAYS SIGNIFICANT. LEADING ZEROS ARE NEVER SIGNIFICANT. IMBEDED ZEROS ARE ALWAYS SIGNIFICANT. TRAILING ZEROS ARE ONLY SIGNIFICANT IF THERE IS A DECIMAL POINT. 4.63 - 3 SIG. FIG 0.000682 - 3 SIG. FIG. 1.072 - 4 SIG. FIG. 300.0 - 4 SIG. FIG. 300 - 1 SIG. FIG. RULES FOR DETERMINING SIGNIFICANT FIGURES
How many significant Figures…..?(Guided Practice) • 1.097800(What is the Rule?) • 4.690(What is the Rule?) • 0.00785(What is the Rule?) • 3000(What is the Rule?) • 3000.00(What is the Rule?)
Independent Practice • Turn to Page 63. • Complete Problems 80 & 91.
How would you explain…. • Tell me how you would explain to someone you were tutoring the process it takes to convert using the metric system.
Home work • Find an item that is measured in metric units of volume….grams. Example – milk 236 mL Example – Rice –a-Roni 192 g
Thought for the Week: • Let no corrupt communication proceed out of your MOUTH!