SCIENTIFIC MEASUREMENTS Unit 2 – For support see Chapter 2 in textbook. -Bechtum

LEARNING TARGETS 1. I can use and convert correct SI units of measurement. 2. I can accurately use scientific notation and significant figures. 3. I can solve problems using dimensional analysis. 4. I can calculate density problems. 5. I can distinguish between precision and accuracy.

WHAT IS THE DIFFERENCE? Qualitative measurement – a measurement that gives descriptive nonnumerical results. (Qualities) ‏ Quantitative measurement – a measurement that gives definite, usually numerical results. (Quantities) ‏

QUANTITATIVE OR QUALITATIVE? 1 minute- turn to your partner! The product was a white powder 760 mL of Acetone was added to the flask The test tube smelled like rotten eggs

SCIENTIFIC NOTATION Numbers are written as a coefficient and 10 raised to a power Examples: x x x 10 18

NUMBERS BIGGER THAN 1: Exponent is Positive Positive Exponents move decimal to the right Examples: Scientific NotationStandard Notation 438, x x 10 3

NUMBERS SMALLER THAN 1: Exponent is Negative Negative Exponents move decimal to the left Examples: Scientific NotationStandard Notation x x 10 -3

PRACTICE TIME! Utilize peers for feedback. Ask questions!

SIGNIFICANT FIGURES -Note Packe t- Any number in a measurement that is certain or estimated (one past measuring device).

DEFINING SIGNIFICANT FIGURES GROUP ACTIVITY (POGIL)! Notes/ Piece of Paper Writing Utensil Complete as a GROUP! Make sure you feel comfortable with the ‘big’ ideas! Assessment on big ideas at ______________

PEER ACTIVITY- SIGNIFICANT FIGURES AND MEASUREMENT ALL GROUP Members participate in building understanding! Below are side jobs to learning and collaborating. Getter 1 (1) Group member that Collects and distributes materials for beginning of activity/day. Getter 2 (2) Group member that Collects and returns materials at the conclusion of activity/day. Reporter (3) Group member that shares thoughts with class; only member that can ask teacher question Starter (4) Group member that begins activities and keeps an eye on the time

PROPER MEASUREMENT Estimate one digit past the smallest division on the measuring device. Include the proper units. Read instruments at eye level.

WHAT IS THE LENGTH?

WHAT IS THE VOLUME?

WHAT IS THE TEMPERATURE?

WHAT IS THE LENGTH?

WHAT IS THE VOLUME?

WHAT IS THE LENGTH?

DEFINE SIGNIFICANT FIGURES IN YOUR OWN WORDS! Share out definitions

ANALYZING SIGNIFICANT FIGURES 650 m -2 Significant Figures km-4 Significant Figures 42.0 s -3 Significant Figures 7000 L-1 Significant Figure kg-4 Significant Figures mL-1 Significant Figure cm-3 Significant Figures 6050 mg-3 Significant Figures Your task is to device a set of “rules” for determine the number of significant figures in a value/number. (3 Minutes!) Be prepared to share out and explain your answers!

RULES OF SIGNIFICANT FIGURES 1.All non-zero numbers are significant. 2.Sandwiched zeros (those that occur between two significant figures) are significant. 3.Zeros that are only placeholders for a decimal are not significant. 4.Zeros at the end of a number that also contains a decimal are significant. 5.Exact numbers (no doubt or uncertainty in the value) may be thought of as having an infinite number of significant figures. These include numbers that were counted or are defined values (i.e., conversion factors)

DETERMINING THE NUMBER OF SIG FIGS MODEL 0.09 cm cm 506 g g cm dm cg ml

PRACTICE TIME 3 minutes! Question 3

MATH RULES USING SIG FIGS Addition and Subtraction answers should be rounded to the same number of decimal places as the measurement with the least number of decimal places Multiplication and Division round the answer to the same number of sig figs as the measurement with the least number of sig figs

MATH USING SIG FIGS MODEL Solve the following and report out using the correct significant figures and units m x m = 1035 m 2 / 42 m = 12.01ml ml + 6 ml = 5546 g – 28.9 g = cm x 3.2 cm x cm =

ROUNDING 5 or higher round up 4 or less round down Examples: 3 Significant Figures

PRACTICE TIME 4 minutes! Question 4, 5, and 6

INTERNATIONAL SYSTEM OF UNITS The International System of Units (SI) is the measurement system used by scientists. Unit of Length = meter (m) ‏ Unit of Time = second (s) Unit of Temperature = Kelvin (K) Unit of Mass = kilogram (kg) ‏ Unit of Amount = mole (mol)

METRIC CONVERSIONS

PRACTICE PROBLEMS Questions 2 and 3!

MASS AND WEIGHT Mass The amount of matter an object is composed of (grams, kg, pounds) Weight The amount of gravitational pull an object has (Newtons) **A person that has a mass of 200 pounds, weighs 889N.

CAN A PERSON BE… massless? weightless?

CHECK FOR UNDERSTANDING Describe the term accuracy in your own words. Describe the term precision in your own words.

UNCERTAINTY IN MEASUREMENTS Accuracy describes how close a measurement comes to the true value. Precision is how close a series of measurements are to one another.

UNCERTAINTY Accurate, Precise, Neither, or Both?

UNCERTAINTY Accurate, Precise, Neither, or Both?

UNCERTAINTY Accurate, Precise, Neither, or Both?

UNCERTAINTY Accurate, Precise, Neither, or Both?

FOUR STUDENT’S LAB RESULTS ARE POSTED BELOW. ASSUMING THAT THE DENSITY OF WATER AT THE SPECIFIED TEMPERATURE OF THE DAY THE LAB WAS CONDUCTED WAS 1.00G/ML ANSWER THE FOLLOWING QUESTIONS. Pipet1Pipet 2Buret 1Buret 2 Student A1.51 g/ml.55 g/ml1.28 g/ml1.42 g/ml Student B1.11 g/ml 1.10 g/ml Student C1.01 g/ml1.00 g/ml0.99g/ml1.00 g/ml Student D1.10 g/ml0.90 g/ml1.15 g/ml0.85 g/ml 1.) Which student has both the highest accuracy and highest precision in their data collected? 2.) Which student has both the lowest accuracy and lowest precision in their data collected? 3.) Which student has the highest precision, but low accuracy in their data collected? 4.) Which student has high accuracy, but low precision in their data collected?

DIMENSIONAL ANALYSIS Purpose: To convert between units using the factor-label method.

CONVERSION FACTORS

DIMENSIONAL ANALYSIS g  kg 2. 3 days  seconds 3. 9,474 mm  cm kL  L cm 3  m cg  mg 7. 1 ft 3  m 3 (Note: 3.28 ft = 1 m) 8. 1 year  minutes lbs  kg (Note: 2.2 lb = 1 kg) km  m kg/L to kg/mL

YOUR TURN! Traveling at 65 miles/hour, how many feet can you travel in 22 minutes? (1 mile = 5280 feet)

1.What is the same? 2.What is different? 3.Which is more dense? Why?

DENSITY Density – the ratio of the mass of an object to its volume Density = mass/volume If a sample of aluminum has a mass of 13.5g and a volume of 5.0 cm 3, what is its density? 2.7 g/cm 3

DENSITY VS. MASS A large metal weight would be both dense and heavy.

DENSITY VS. MASS A single balloon would be neither dense nor heavy.

DENSITY VS. MASS A small metal weight would be dense, but not particularly heavy

DENSITY VS. MASS Enough balloons will be heavy, but still aren't dense.

DENSITY

SOLVING DENSITY PROBLEMS Given Unknown Equation Substitute Solve Calculate the density of a material that has a mass of g and a volume of 13.5 cm 3. m D V

SOLVING DENSITY PROBLEMS Given Unknown Equation Substitute Solve The density of silver is g/cm 3. If a sample of pure silver has a volume of cm 3, what would the mass be? m DV

GROUP WORK SOLVING DENSITY PROBLEMS Given Unknown Equation Substitute Solve What is the mass of a 350 cm 3 sample of pure silicon with a density of g/ cm 3 ? m D V

DENSITY LAB Once you have finished collecting your data and cleaned your station return to your seat and complete the questions, INDIVIDUALLY! DUE BEFORE YOU LEAVE TODAY (place in basket on bookshelf) Graph it! Complete the Mass vs. Volume Graph Practice Sheet. Practice ALL the remaining questions in your packet. (solutions on front table)

LEARNING TARGET CHECK Will Complete INDIVIDUALLY No Notes For next time… Finish reading pages Continue working through packet.