Used to communicate the accuracy of measurements Significant Figures Used to communicate the accuracy of measurements 9/9/14 start here 1st period.

When is a digit significant? The digits 1 through 9 are always significant Zeros may or may not be significant

How do I determine significant figures We will use a method called Atlantic- Pacific to determine the number of significant figures.

Using Atlantic-Pacific Method Is there a decimal? No: count from the Atlantic side of the number starting with first non-zero number How many significant figures in 9500? 9500 2

More Practice How many significant figures in 100 607100 8008

Using Atlantic-Pacific Method Is there a decimal? Yes: count from the Pacific side of the number starting with first non-zero number How many significant figures in 0.00316? 0.0000034 2

More Practice How many significant figures in 0.2100 0.000910 5.2030 900.

Assignment Complete page 2 of Math Guided Practice.

Math Guided Practice p.2 100.0 100 100.00 1,002 0.011 0.00010 1.02 0.180 110.00 140,000,000 1.00 x 1024 1.0030 x 1013 1.08 x 105 950 0.850 129 0.198 4050 980890 3.005 .0100 10 580 580. 0.0058 0.006802

Scientific Notation 1235060 1.23506 x 105 1.23506 x 10x Move decimal point so there is one non- zero digit to the left of the decimal point. Remember to include only significant figures when you rewrite number with a decimal place. Count the number of places the decimal point was moved. This becomes the power for the 10x. Since 123506 is greater than 1 the power will be positive.

Scientific Notation used to make both really big and small numbers easier to work with. Numbers greater than one will have positive exponent Numbers less than one will have negative exponent Preserve the number of significant figures

Scientific Notation Practice 123615 1200 1520. 695

Scientific Notation Practice 0.01260 0.3100 0.009807 0.0000031222

Scientific Notation to Standard Notation 1.276 x 105 = 1.290 x 10-3 = 127600 0.001290

Math Guided Practice p.1 1) 0.0050 __________ 2) 16000 __________ 3) 780500 __________ 4) 0.0001020 __________ 5) 185000 __________ 6) 3504000000 __________ 7) 2052.8 __________ 8) 4.008500 __________ 9) 78 000000 __________ 10) 0.000000205100 __________ 4th Period Start here on 9/10. Students finished as homework. Take to fire alarm and fume hood. 6th Start here on 9/10

Math Guided Practice p.1 11) 1 x 108 __________

Entering Scientific Notation in a Calculator Type in the number Press the EE or EXP key Type in the exponent. Remember to add the “-” if the exponent is negative. Use the EE or EXP key only! Start here 1st period on 9/10

Scientific Notation 21) (3 x 108) / (2.5 x 108) __________ 25) (1 x 108) x (2.00 x 108) __________ 26) (4.6 x 108) x (2 x 107) __________ 27) (1 x 108) x (2 x 109) __________ 28) (1.5 x 1017) x (3 x 1010) _________ 15.5 or 1.55 x 101 0.15 or 1.5 x 10-1 2.5 x 10-11 2 x 1016 9.2 x 1015 2 x 1017 4.5 x 1027

Mathematical Operation with Significant Figures p Mathematical Operation with Significant Figures p. 3 Math Guided Practice An answer cannot be more accurate than the least accurate measurement in the operation

Addition and Subtraction with Significant Figures 1.21 + 2.1 + 3.22 = 6.5 When adding or subtracting numbers, count the NUMBER OF DECIMAL PLACES to determine the number of significant figures. The answer cannot CONTAIN MORE PLACES AFTER THE DECIMAL POINT THAN THE SMALLEST NUMBER OF DECIMAL PLACES in the numbers being added or subtracted.

Addition and Subtraction with Significant Figures 4.85 1) 1.005 + 3.84 ___________ 2) 198.95 + 1.1 ___________ 3) 9.85 + 1 ______________ 4) 5.03 + 2.180 ___________ 5) 4.0588 + 100 __________ 200.1 11 7.21 104

Addition and Subtraction with Significant Figures 6) 8.23 - 1.09 _____________ 7) 3.62 - 1.6 ______________ 8) 212.1 - 9.95 ____________ 9) 0.009 - 0.00051 _________ 10) 0.962 - 0.53213 ________ 7.14 2.0 202.2 0.008 0.430

Multiplication and Division with Significant Figures 3.2 x 1.21 x 6.123 = When multiplying or dividing numbers, count the NUMBER OF SIGNIFICANT FIGURES for each number. The answer must be rounded to the smallest number of significant figures.

Multiplication and Division with Significant Figures 1) 1.58 x 2.004 __________ 2) 2 x 3.14 _____________ 3) 0.0048 x .145 __________ 4) 78500 x 15 _____________ 5) 0.04501 x 0.02 __________ 3.17 6 0.00070 1.2 x 106 9 x 10-4 Start 3rd om 9/11

Multiplication and Division with Significant Figures 6) 12.6 / 6 __________ 7) 0.0458 / 0.00002 __________ 8) 12.005 / 10 __________ 9) 25.255 / 4.56 __________ 10) 0.01 / 1.368 __________ 2 2 x 103 1 5.54 0.007

MSDS Material Safety Data Sheet http://www.youtube.com/watch?v=elRzB8xTM3w

MSDS Read GPS 2 Resource Notes p. 3 on Material Safety Data Sheets. Complete CH-1b MSDS Scavenger Hunt using the MSDS documents on your table.

NFPA Labels http://www.youtube.com/watch?v=ETPY14maDbw

Taking Measurements GPS 2 Resource Notes pp. 3-4 When taking measurements: Read to the smallest mark on the instrument Estimate one digit past the smallest mark

Measuring Volume Determine the volume contained in a graduated cylinder by reading the bottom of the meniscus at eye level. Read the volume using all certain digits and one uncertain digit. Certain digits are determined from the calibration marks on the cylinder. The uncertain digit (the last digit of the reading) is estimated.

Reading the Graduated Cylinder Liquids in glass and some plastic containers curve at the edges Changing the diameter of the cylinder will change the shape of the curve This curve is called the MENISCUS

Reading the Graduated Cylinder Your eye should be level with the top of the liquid You should read to the bottom of the MENISCUS

Use the graduations to find all certain digits There are two unlabeled graduations below the meniscus, and each graduation represents 1 mL, so the certain digits of the reading are… 52 mL.

Estimate the uncertain digit and take a reading The meniscus is about eight tenths of the way to the next graduation, so the final digit in the reading is . 0.8 mL The volume in the graduated cylinder is 52.8 mL.

Reading a graduated cylinder GPS 2 Resource Notes p. 9 All of the equipment below measures volume in mL but the scales for each are different. 7.5mL 16.5mL 3.80mL

6.62mL 10 mL Graduated Cylinder What is the volume of liquid in the graduate? 6.62mL

11.5 mL 25mL graduated cylinder What is the volume of liquid in the graduate? 11.5 mL

100mL graduated cylinder 52.7mL What is the volume of liquid in the graduate? 52.7mL

Practice Reading the Graduated Cylinder What is this reading? 61.2 ml

Practice Reading the Graduated Cylinder What is this reading? 42.9 ml

Measuring Liquid Volume What is the volume of water in each cylinder? Images created at http://www.standards.dfes.gov.uk/primaryframework/downloads/SWF/measuring_cylinder.swf A B C Pay attention to the scales for each cylinder.

What is the volume in the buret?

What is the volume in the buret?

The Thermometer Determine the temperature by reading the scale on the thermometer at eye level. Read the temperature by using all certain digits and one uncertain digit. Certain digits are determined from the calibration marks on the thermometer. The uncertain digit (the last digit of the reading) is estimated. On most thermometers encountered in a general chemistry lab, the tenths place is the uncertain digit.

Do not allow the tip to touch the walls or the bottom of the flask. If the thermometer bulb touches the flask, the temperature of the glass will be measured instead of the temperature of the solution. Readings may be incorrect, particularly if the flask is on a hotplate or in an ice bath.

Reading the Thermometer Determine the readings as shown below on Celsius thermometers: _ _ . _ C 8 7 4 _ _ . _ C 3 5

Measuring Solid Volume Math Guided Practice p. 6 We can measure the volume of regular object using the formula length x width x height. 10 cm 9 cm 8 cm _____ X _____ X _____ = _____

Measuring Solid Volume Math Guided Practice p. 6 http://resources.edb.gov.hk/~s1sci/R_S1Science/sp/en/syllabus/unit14/new/testingmain1.htm We can measure the volume of irregular object using water displacement. Amount of H2O with object = ______ Amount of H2O without object = ______ Difference = Volume = ______

Practice Reading the Graduated Cylinder What is this volume? 47.0 ml

Online Practice Reading a graduated cylinder http://w1imr.cnm.edu/apps/chemlab/reading_ a_meniscus.swf Reading a buret http://w1imr.cnm.edu/apps/chemlab/burette.s wf Reading a ruler http://w1imr.cnm.edu/apps/chemlab/reading_ a_ruler.swf

Homework Complete p. 3 in Math Guided Practice Complete Measuring Practice Complete p. 6 Volume in Math Guided Practice Separation Techniques Practice Start here with 7th on 9/11

Experimental Design GPS 2 Resource Notes p. 5 Dependent Variable(s) This is the response that you are measuring Independent Variable(s) These are the ones you are controlling or manipulating

Experimental Design Control This is what you use as a comparison. Constants Constants do not change throughout the experiment.

Experimental Design Example: A student is determining the rate at which a certain substance evaporates by checking the volume every 60 minutes. I.V. = time (minutes) D.V. = volume

Experimental Design Example: A balloon full of air is heated slowly to observe its change in volume. I.V. = temperature D.V. = volume

Parts of the Experiment Practice What is the I.V., D.V. and Control? Smithers thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task (in this case, they're supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks.

Observations GPS 2 Resource Notes p. 5 Qualitative Descriptive data such as color, texture, relative size, or shape. Quantitative Numberical data such as mass, volume, or pH.

Accuracy vs Precision GPS 2 Resource Notes p. 5 Describes how close an experimental determined value is compared to the known or true value. Precision Describes how close the experimental trials are to each other.

Accuracy vs Precision Practice Accurate, Precise, Both, or Neither? 78.1mL, 43.9mL, 2mL

Percent Error GPS 2 Resource Notes p.6 Math Guided Practice p. 5 |Experimental Value – Theoretical Value| x 100 Theoretical Value A student measured the string as 1.25m long. The teacher said it was actually 2.12m long. What was the student’s percent error?

Graphing Data Trial Temp. Volume 1 25 101.2 2 30 102.1 3 35 103.2 4 40 105.0 5 45 106.5 6 50 108.4 7 55 110.1 8 60 111.3 9 65 112.8 10 70 114.0

Sources of Error Are you missing steps in your procedure? Procedural error Are you missing steps in your procedure? Are steps of your procedure making incorrect assumptions? Are you incorrectly measuring your product/result? Systematic error Consistently causes measurements to be too high or too low (a systematic error will always throw off you measurements by the same amount and in the same direction) Ex: a balance is not properly zeroed or an instrument is not properly calibrated Random error A source of measurement error due to the estimation of the last significant figure. The more trials run, the less random error will affect your results.

Dimensional Analysis (Conversions) GPS Resource Notes pp Dimensional Analysis (Conversions) GPS Resource Notes pp. 11-12 Math Guided Practice p. 4

Homework Complete Accuracy vs Precision Practice Complete Dimensional Analysis Practice Complete Parts of Experiment Practice

Density GPS 2 Resource Notes p. 13 Math Guided Practice p. 6

Laboratory Techniques GPS 2 Resource Notes p. 1