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Scientific Method starting on p. 29 Scientific method – Scientific method – System – System – Hypothesis- Hypothesis- Testing hypothesis- Testing hypothesis-

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Presentation on theme: "Scientific Method starting on p. 29 Scientific method – Scientific method – System – System – Hypothesis- Hypothesis- Testing hypothesis- Testing hypothesis-"— Presentation transcript:

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2 Scientific Method starting on p. 29 Scientific method – Scientific method – System – System – Hypothesis- Hypothesis- Testing hypothesis- Testing hypothesis- Model – Model – Theory- Theory- Stages in the Scientific Method Stages in the Scientific Method

3 Look at page 31 Stages in scientific method Whoosh!

4 SYSTEM SURROUNDINGS Energy Released C 3 H 7 OH + O 2 CO 2 + H 2 OPotential Energy

5 Analyze this graph and formulate a Hypothesis p. 30 Section 1 Scientific Method Chapter 2

6 Homework Chapter 2 Section 1: P. 31 ( 1-5)

7 Qualitative and Quantitative Qualitative Qualitative – describes qualities, characteristics, textures, etc. Descriptions without numbers Quantitative Quantitative – Describes quantities, mass, volume, length (numbers)

8 Units of Measurement Quantity – what is being measured. Quantity – what is being measured. example: volume, length, mass Unit – a standard of measurement Unit – a standard of measurement example: liter, meter, kilogram

9 Lesson 1: Length T. Trimpe 2008

10 English vs. Metric Units Left Image: Right Image: Which is longer? A. 1 mile or 1 kilometer B. 1 yard or 1 meter C. 1 inch or 1 centimeter 1.6 kilometers 1 mile 1 yard = meters 1 inch = 2.54 centimeters

11 Metric Units The basic unit of length in the metric system in the meter and is represented by a lowercase m. Metric Units 1 Kilometer (km) = 1000 meters 1 Hectometer (hm) = 100 meters 1 Meter = 100 Centimeters (cm) 1 Dekameter (dam) =10 meters 1 Meter = 1000 Millimeters (mm)1 Meter = 10 Decimeters (dm) Which is larger? A. 1 meter or 105 centimeters B. 4 kilometers or 4400 meters C. 12 centimeters or 102 millimeters D millimeters or 1 meter

12 Measuring Length Ruler: How many millimeters are in 1 centimeter? What is the length of the line in centimeters? _______cm What is the length of the line in millimeters? _______mm What is the length of the line to the nearest centimeter? ________cm HINT: Round to the nearest centimeter – no decimals. 1 centimeter = 10 millimeters

13 Lesson 2: Mass T. Trimpe 2008

14 English vs. Metric Units Which is larger? 1. 1 Pound or 100 Grams 2. 1 Kilogram or 1 Pound 3. 1 Ounce or 1000 Milligrams 1 pound = grams 100 kg = 220 pounds 1 ounce of gold = 28,349.5 milligrams

15 Metric Units Mass refers to the amount of matter in an object. The base unit of mass in the metric system is the kilogram and is represented by kg. Metric Units 1 Kilogram (kg) = 1000 Grams (g) 1 Hectogram (hg) = 100 grams 1 Gram (g) = 1000 Milligrams (mg)1 Dekagram (dag) =10 grams 1 Gram (g) = 100 Centigrams (cg) 1 Gram = 10 Decigrams (dg) Which is larger? A. 1 kilogram or 1500 grams B milligrams or 1 gram C. 12 milligrams or 12 kilograms D. 4 kilograms or 4500 grams Kilogram Prototype Image -

16 Measuring Mass Top Image: Bottom Image: We will be using triple-beam balances to find the mass of various objects. The objects are placed on the scale and then you move the weights on the beams until you get the lines on the right-side of the scale to match up. Once you have balanced the scale, you add up the amounts on each beam to find the total mass. What would be the mass of the object measured in the picture? _______ + ______ + _______ = ________ g

17 Lesson 3: Volume T. Trimpe 2008

18 English vs. Metric Units Which is larger? A. 1 liter or 1 gallon B. 1 liter or 1 quart C. 1 milliliter or 1 fluid ounce 1 gallon = 3.79 liters It would take approximately 3 ¾ 1-liter bottles to equal a gallon. 1 fl oz = ml 1 12-oz can of soda would equal approximately 355 ml. 1 quart = liters

19 Metric Units Volume is the amount of space an object takes up. The base unit of volume in the metric system is the liter and is represented by L. Metric Units 1 liter (L) = 1000 milliliters (mL) 1 milliliter (mL) = 1 cm 3 1 Kiloliter (kL) = 1000 Liters (L) 1 Hectoliters (hL) = 100 Liters 1 Dekaliter (daL) =10 Liters1 Liter (L) = 100 Centiliters (cL) 1 Liter (L) = 10 Deciliters (dL) Which is larger? A. 1 liter or 1500 milliliters B. 200 milliliters or 1.2 liters C. 12 cm 3 or 1.2 milliliters Liter Image:

20 Measuring Volume Top Image: Bottom Image: We will be using graduated cylinders to find the volume of liquids and other objects. Read the measurement based on the bottom of the meniscus or curve. When using a real cylinder, make sure you are eye-level with the level of the water. What is the volume of water in the cylinder? _____mL What causes the meniscus? A concave meniscus occurs when the molecules of the liquid attract those of the container. The glass attracts the water on the sides.

21 Measuring Liquid Volume Images created at What is the volume of water in each cylinder? Pay attention to the scales for each cylinder.

22 Measuring Solid Volume Click here for an online activity about volumeClick here for an online activity about volume. Choose Lessons Volume & Displacement 10 cm 9 cm 8 cm We can measure the volume of regular object using the formula length x width x height. _____ X _____ X _____ = _____ n/syllabus/unit14/new/testingmain1.htm We can measure the volume of irregular object using water displacement. Amount of H 2 O with object = ______ About of H 2 O without object = ______ Difference = Volume = ______

23 Converting Units Conversion Factor – equal ratio that enables you to change one unit to another Conversion Factor – equal ratio that enables you to change one unit to another Example: Example: 1kg = 1000 g 1kg1000g 1000g or 1 kg

24 Practice 1. 1.____g = 57.8 mg 2. 2._____km = 125m ____mL = 0.65L ____cg = 5.7mg ____L = 286 mL 6. 6.____m = 112 cm ___mg = 9.7 cg ___ kg = 21 mg __ mm = 0.003km

25 SOLVE ___ g = 125mg kg +95cg+2g 2 g. 95 g 150 g.125g g

26 Solve 1. 1.___g=125mg +.15kg + 95cg + 2g 2. 2.___cm=.13km + 29mm + 113cm + 1.5m 3. 3.___g=2835mg + 245cg + 3g +.23kg

27 Memorize! 1 L = 1000ml = 1000cm 3 1mL = 1cm 3 And all other conversions on green sheet

28 Sample Problem A – pg. 14 Convert 0.851L to ml Convert 0.851L to ml

29 Sample problems Convert 253 ml to liters Convert 253 ml to liters Answer: Answer:

30 Sample Problem Convert 1258 cm to m Convert 1258 cm to m Answer: Answer:

31 Sample Problem Convert 15 g to kg Convert 15 g to kg Answer: Answer:

32 Sample Problem Convert 5.25 hours to seconds Convert 5.25 hours to seconds Answer: Answer:

33 Density A physical property. A physical property. Density equals the mass of an object divided by its volume. Density equals the mass of an object divided by its volume. D =m/V D =m/V Units you will see: g/ml or g/cm 3 Units you will see: kg/m 3 or g/ml or g/cm 3 Density can be used to identify substances. Density can be used to identify substances.

34 Derived SI Units p. 36 QuantityQuantity Symbol UnitUnit Abbreviation AreaASquare meter m2m2 VolumeVCubic meter m3m3 DensityDKilogram per cubic meter kg m 3

35 SI Base Units p. 34

36 Density Practice What is the density of a block of marble that occupies 310cm 3 and has a mass of 853 grams?

37 Density Practice A diamond has a density of 3.26 g/cm 3. What is the mass of a diamond that has a volume of 0.35 cm 3 ?

38 Density Practice What is the volume of a sample of liquid mercury that has a mass of 76.2g, given that the density of mercury is 13.6 g/ml ?

39 Now… Density Worksheet 1 & 2 Homework: Quiz over p. 42 (1-5) – next class

40 Uncertainty in Measurement A digit that must be estimated is called uncertain. A measurement always has some degree of uncertainty

41 Why Is there Uncertainty? Measurements are performed with instruments Measurements are performed with instruments No instrument can read to an infinite number of decimal places No instrument can read to an infinite number of decimal places

42 Which of these balances has the greatest uncertainty in measurement?

43 Accuracy vs. Precision Accuracy vs. Precision Accuracy - how close a measurement is to the accepted value Accuracy - how close a measurement is to the accepted value Precision - how close a series of measurements are to each other Precision - how close a series of measurements are to each other ACCURATE = CORRECT PRECISE = CONSISTENT

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47 Experimental Data Carbon = amu Carbon = amu During your experiment, you obtained the following values: , , During your experiment, you obtained the following values: , , Are these Precise or Accurate? Are these Precise or Accurate?

48 Percent Error Percent Error Indicates accuracy of a measurement Indicates accuracy of a measurement % error = Accepted – Experimental x 100 Accepted % error = Accepted – Experimental x 100 Accepted

49 Percent Error A student determines the density of a substance to be 1.40 g/mL. Find the % error if the accepted value of the density is 1.36 g/mL. A student determines the density of a substance to be 1.40 g/mL. Find the % error if the accepted value of the density is 1.36 g/mL. % error = 1.36 – 1.40 x 100= 1.36 % error = 1.36 – 1.40 x 100= 1.36 % error = %

50 Significant Figures Significant Figures Indicate precision of a measurement. Indicate precision of a measurement. Recording Sig Figs Recording Sig Figs –Sig figs in a measurement include the known digits plus a final estimated digit 2.35 cm

51 Rules for Counting Significant Figures - Details Nonzero integers always count as significant figures. Nonzero integers always count as significant figures has 3456 has 4 sig figs. 4 sig figs.

52 Rules for Counting Significant Figures - Details Zeros Zeros -Beginning zeros do not count as significant figures. -Beginning zeros do not count as significant figures has has 3 sig figs 3 sig figs

53 Rules for Counting Significant Figures - Details Zeros Zeros - Middle zeros always count as significant figures. - Middle zeros always count as significant figures has has 4 sig figs. 4 sig figs.

54 Rules for Counting Significant Figures - Details Zeros Zeros End zeros are significant only if the number contains a decimal point. End zeros are significant only if the number contains a decimal point has has 4 sig figs. 4 sig figs.

55 Rules for Counting Significant Figures - Details Exact numbers have an infinite number of significant figures. Exact numbers have an infinite number of significant figures. 1 inch = 2.54 cm, exactly 1 inch = 2.54 cm, exactly

56 , Significant Figures Significant Figures Counting Sig Fig Examples , ____ sig figs ___ sig figs ____ sig figs

57 Sig Fig Practice #1 How many significant figures in each of the following? How many significant figures in each of the following? m m 5 sig figs kg kg 4 sig figs L L 5 sig figs 3.29 x 10 3 s 3.29 x 10 3 s 3 sig figs cm cm 2 sig figs sig figs

58 Significant Figures Calculating with Sig Figs Calculating with Sig Figs –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 SF3 SF

59 Rules for Significant Figures in Mathematical Operations 6.38 x 2.0 = 6.38 x 2.0 = (2 sig figs) (2 sig figs)

60 Sig Fig Practice #2 Calculation Calculator says: Answer Calculation Calculator says: Answer 3.24 m x 7.0 m ____ m 2 __ m m x 7.0 m ____ m 2 __ m g ÷ 23.7cm 3 ________ g/cm 3 ____g/cm g ÷ 23.7cm 3 ________ g/cm 3 ____g/cm cm x 2.371cm ______ cm 2 ____ cm cm x 2.371cm ______ cm 2 ____ cm m ÷ 3.0 s ________ m/s ____ m/s 710 m ÷ 3.0 s ________ m/s ____ m/s

61 Significant Figures Calculating with Sig Figs (cont) Calculating with Sig Figs (cont) –Add/Subtract - The # with the lowest decimal value determines the place of the last sig fig in the answer mL mL 7.85 mL 7.9 mL 3.75 mL mL 7.85 mL

62 Significant Figures Calculating with Sig Figs (cont) Calculating with Sig Figs (cont) –Exact Numbers do not limit the # of sig figs in the answer. Counting numbers: 12 students Counting numbers: 12 students Exact conversions: 1 m = 100 cm Exact conversions: 1 m = 100 cm 1 in any conversion: 1 in = 2.54 cm 1 in any conversion: 1 in = 2.54 cm

63 Significant Figures 5. (15.30 g) ÷ (6.4 mL) Practice Problems = g/mL 18.1 g 18.1 g g g g 4 SF2 SF 2.4 g/mL 2.4 g/mL 2 SF

64 Scientific Notation In science, we deal with some very LARGE numbers: In science, we deal with some very LARGE numbers: 1 mole = mole = In science, we deal with some very SMALL numbers: In science, we deal with some very SMALL numbers: Mass of an electron = Mass of an electron = kg kg

65 Imagine the difficulty of calculating the mass of 1 mole of electrons! kg kg x x ?????????????????????????????????? ??????????????????????????????????

66 Scientific Notation: A method of representing very large or very small numbers in the form: A method of representing very large or very small numbers in the form: M x 10 n M x 10 n M is a number between 1 and 9.9 M is a number between 1 and 9.9 n is an integer n is an integer

67 Step #1: Insert an understood decimal point. Step #2: Decide where the decimal must end up so that one number is to its left up so that one number is to its left Step #3: Count how many places you bounce the decimal point the decimal point Step #4: Re-write in the form M x 10 n

68 2.5 x 10 9 The exponent is the number of places we moved the decimal.

69 Step #2: Decide where the decimal must end up so that one number is to its left up so that one number is to its left Step #3: Count how many places you bounce the decimal point the decimal point Step #4: Re-write in the form M x 10 n 12345

70 5.79 x The exponent is negative because the number we started with was less than 1.

71 PERFORMING CALCULATIONS IN SCIENTIFIC NOTATION

72 Scientific Notation 7. 2,400,000 g kg km mm Practice Problems ________ g ________ g ________ kg ________ km _______ mm

73 Scientific Notation Calculating with Sci. Notation Calculating with Sci. Notation (5.44 × 10 7 g) ÷ (8.1 × 10 4 mol) = 5.44 EXP EE ÷ ÷ EXP EE ENTER EXE = = 670 g/mol= 6.7 × 10 2 g/mol Type on your calculator:

74 Direct Proportions The quotient of two variables is a constant The quotient of two variables is a constant As the value of one variable increases, the other must also increase As the value of one variable increases, the other must also increase As the value of one variable decreases, the other must also decrease As the value of one variable decreases, the other must also decrease The graph of a direct proportion is a straight line The graph of a direct proportion is a straight line

75 Inverse Proportions The product of two variables is a constant The product of two variables is a constant As the value of one variable increases, the other must decrease As the value of one variable increases, the other must decrease As the value of one variable decreases, the other must increase As the value of one variable decreases, the other must increase The graph of an inverse proportion is a hyperbola The graph of an inverse proportion is a hyperbola

76 Proportions Direct Proportion Direct Proportion Inverse Proportion Inverse Proportion y x y x


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