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Unit 1- Scientific Measurement/ Matter and Energy. Let’s get our minds in chemistry mode! Find the pattern. https://www.youtube.com/watch?v=vJG698U2Mvo. Find the pattern…. _ _ T T F F S S E _ _ E T T F F S S E _ _. Last one….

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## Unit 1- Scientific Measurement/ Matter and Energy

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**Find the pattern…**_ _ T T F F S S E _ _ E T T F F S S E _ _**Last one…**Rearrange the following letters so as to form one word: NEW DOOR**Per. 5- Tuesday, 9/13**• Quiz 1 this Thursday! • Elements 1-20 (spelling counts!) • Measurements • Accuracy vs. Precision • Sig Figs**There are two types of data we can collect in any lab:**Types of Data Qualitative: Descriptive, non-numerical Quantitative: Numerical; can be counted**Taking a good measurement*****When making a measurement, include all of the digits that are known, plus one estimated digit.**Accuracy vs. Precision**Accuracy: how close your measurement, calculation, etc. is to the actual answer Precision: getting the same results for multiple trials**Accurate and precise**Not accurate, not precise Precise, not accurate**Significant Figures**• The # of sig figs in a measurement is equal to the number of digits that are known, plus the last digit which is estimated.**Rules for Counting Sig Figs**• Non-zero numbers are always significant Ex. 23.45 grams Ex. 29.2 mL Ex. 13.249 cm**Rules for Counting Sig Figs**2) All zeroes between other numbers are significant Ex. 12.05 cm Ex. 1.002 L Ex. 103 mm**Rules for Counting Sig Figs**3) For numbers less than one, leading zeroes are NOT significant (bracket rule) Ex. 0.045g Ex. 0.000805L**Rules for Counting Sig Figs**4) Zeroes after a decimal point and after a non-zero number are significant Ex. 0.00690 mL Ex. 32.00 cm Ex. 64.020 L**Rules for Counting Sig Figs**5) For large numbers, trailing zeroes are only significant if there is a decimal point Ex. 13500L Ex. 13500.L Ex. 13500.00L**Before Rule #6…**A quick review of scientific notation**Rules for Counting Sig Figs**6) For numbers in scientific notation: count the number of sig figs in the coefficient Ex. 2.35 x 102 Ex. 6.905 x 10-3 Ex. 1.200 x 104**White Boards**How many sig figs are in the following numbers? • 145,000 m • 4.503 x 104 L • 7.020 g • 9,001.00 mL • 870.9 m • 0.000059 g • 3.6040 cm • 70,050 L**Rounding w/ Sig Figs**Round to three sig figs: 0.16250 g Round to two sig figs: 0.00987 mL Round to one sig fig: 0.171 L Round to two sig figs: 98.7 mL**More on Sig Figs…**• How would we write 40,000 kg as 2 sig figs? • Water from 3 small graduated cylinders was placed in one, larger graduated cylinder. When added together, the total volume of the water was 63.52 mL. What was the average amount of water in each individual graduated cylinder?**Calculations with Sig Figs**• Add/Subtract: count decimal places • Multiply/Divide: count sig figs**Adding/Subtracting**• 2.3 g + 1.05g + 3.230g = 2) 12.306g – 1.10g = 3) 5.21 mL + 6.9 mL + 23 mL =**Multiplying/Dividing**1) 5.4 m x 7.7 m 2) 15.28g ÷ 2.4 mL 3) 36.03 cm x 2 cm**Per. 1 and 5- Mon, 9/19**• Quiz 2 will have ALL 40 elements • Period 1- Quiz Friday • Period 5- Quiz Thursday**The International System of Units (SI)**m Length meter kg Mass kilogram s Time second Amount of substance mol mole K Temperature Kelvin**SI Conversions**• Remember- King Henry Died by Drinking Chocolate Milk • When we convert, we are only changing units…NOT the quantity**Powers of Ten Video**• https://www.youtube.com/watch?v=0fKBhvDjuy0**Practice**31.2 cm = ______km 0.98 km = _______ m 120.9 g = _______ kg 312.2 cg = ______ mg**More Prefixes…**• In chemistry we use very small units to describe the size of an atom. • micro, nano, etc. • Ex) How many millimeters are in 80.35 micrometers?**Per. 1- Tuesday, 9/20**• Quiz Friday**Dimensional Analysis**• In order to do dimensional analysis, we need to use conversion factors. • Conversion factor: a ratio of equivalent measurements • Examples:**Example Problems:**1 inch = 2.54 cm 1) How many inches are in 8.71 cm? 2) How many inches are in 5.900 m?**Example Problems:**1 mile = 5280 feet 1 mile= 1.61 km 3) How many total feet would you run in a 10.0 km race?**Example Problems:**4 qt = 1 gal 1 L = 1.057 qt 4) How many gallons are in 0.00890 liters?**What is density?**• The density of a substance is defined as its mass per unit volume mass volume D =**Units for Density**Mass (grams) D = Volume (cm3 or mL) g g D = D = or mL cm3**Water Displacement and % Error**• Aluminum cylinder**Does density depend on the amount of a substance you have??**• The density of a substance will never change- no matter how much or how little of that substance you have!**A student measures the mass and volume of a piece of iron to**find its density. Mass = 21.8 g Volume = 2.98 mL a) Based on the student’s data, what is the determined density of iron? b) Using Table S, calculate the student’s percent error.**Numbers with Unlimited Sig Figs….**• 3 beakers are put on a scale and the total mass combined is 63.52 grams. What is the average mass of each beaker? ***All values from the RT have an unlimited # of sig figs (ex. 1 atm)

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