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Section 3.1

Chapter 3: Scientific Measurement. Section 3.1. Scientific Notation or how to deal with large numbers. Chemistry uses very large and very small numbers . Scientific Notation - coefficient x 10 raised to a power 10> coefficient > 1 4.32 x 10 2. exponent. coefficient.

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Section 3.1

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  1. Chapter 3: Scientific Measurement Section 3.1

  2. Scientific Notationor how to deal with large numbers . . .

  3. Chemistry uses verylarge and verysmall numbers. Scientific Notation - coefficient x 10 raised to a power • 10> coefficient > 1 4.32 x 10 2 exponent coefficient

  4. exponent shows how many times the coefficient is multiplied by 10. 4.6 x 104 = 4.6 x 10 x 10 x 10 x 10 = 46,000

  5. Scientific Notation to Regular Notation If the exponent is positive, move the decimal point to the right  5.3 x 106 = 5,300,000 If the exponent is negative, move the decimal point to the left  5.3 x 10 - 6 = 0.0000053

  6. Regular Notation to Scientific Notation Use + if you moved the decimal to the left. Use – if you moved the decimal to the right 630,000,000 = 6.3 x 10 8 0.000000063 = 6.3 x 10 - 8

  7. If coefficient smaller then exponent bigger; if coefficient bigger then exponent will get smaller. 54256 = 5.4256 x 10 4 0.00248 = 2.48 x 10 - 3 Remember! only 1number in front of decimals

  8. Let’s Practice . . . Do I move the decimal to the right or the left? • 7348000 = 7.348 x 10 6 • 0.24854 = 2.4854 x 10 - 1 • 5842000 = 5.842 x 10 6 • 0.0000124 = 1.24 x 10 - 5

  9. Sometimes you may need to convert between notations . . . If you make one side bigger, make the other side smaller Example: 6.3 x 104 = _______ x 102 6.3 x 102 = _______ x 104 6.3 x 10-4 = _______ x 10-2 6.3 x 10-3 = _______ x 102 630 .063 .063 .000063

  10. Scientific Notation: Multiplication • Multiply the coefficients • Add the exponents (3.0 x 104) x (2.0 x 102) = (3.0 x 2.0) x 104+2 = 6.0 x 106 make sure final coefficients – between 1 and 10!!!

  11. Scientific Notation: Division • Divide the coefficients • Subtract the exponents 6.0 x 105 2.0 x 103 = (6.0 / 2.0) x 105-3 = 3.0 x 102 why?10 x 10 x 10 x 10 x 10 10 x 10 x 10

  12. Scientific Notation: Addition and Subtraction • 1st make exponents the same, • then align decimal points 5.40 x 10 3 + 6.00 x 10 2 ________________ 5.40 x 103 + 0.600 x 103 __________________ 6.00 x 103

  13. Significant Figures Measurements not more reliable than measuring tool Significant Figures = all digits known precisely in a measurement, + 1 estimated digit SIX RULES to determine if measured values are significant:

  14. With the ruler, measure the width of your page of notes What is its’ width? How many digits are you sure of? How many do you interpolate or “guess”? How many significant digits in total?

  15. T

  16. Sig. Figs. in Calculations Adding/Subtracting answer rounded to the leastnumber of decimal places in agreement 12.52 349.0 + 8.24 369.76 = 369.8 = = 3.698 x 102

  17. Multiplying and Dividing round number w/ the least sig. figs. 7.55 x 0.34 2 sig. figs. 2.567 = 2.6

  18. Examples 61.2 34.61 9.35 - 17.3 + 8.6 17.31 79.15 = 79.2 1.73 x 101 7.92 x 101 1.5 2.10 x .70 = 1.47 =

  19. Percent Error Used to evaluate accuracy of a measurement in lab. • Two parts: • Actual Value –‘correct’ value • 2. Experimental Value - measured in the lab

  20. The Equation . . . Actual Amt - Experiment Amt % Error = x 100 Actual Amt. Will you have negative % errors?

  21. Section 3.3 International System Of Units

  22. Why is it important to have one standard for measurement? To ensure consistent & repeatable measurements

  23. Why is the metric system preferred over the English system? • All units multiplies of 10. • Easy to convert

  24. Which countries don’t use metrics in everyday life? Only 3 Liberia (West Africa) Myanmar (or Burma S.W. Asia) United States

  25. Metric System 1st established in France 1790’s • 1960, International System of Units(SI) SI • SI - revised version of metric system

  26. Quantity Unit Symbol length meter m mass kilogram kg time second s electric current ampere A thermodynamic temperature kelvin K amount of substance mole mol luminous intensity candela cd International System of Units • Seven SI Units:

  27. Common SI-English Equivalent Quantities Table 1.4 English to SI Equivalent Quantity SI Unit SI Equivalent English Equivalent Length 1 kilometer(km) 1000(103)m 0.62miles(mi) 1 mi = 1.61km 1 meter(m) 100(102)m 1.094yards(yd) 1 yd = 0.9144m 1000(103)mm 39.37inches(in) 1 foot (ft) = 0.3048m 1 centimeter(cm) 0.01(10-2)m 0.3937in 1 in = 2.54cm (exactly!) 1 kilometer(km) 1000(103)m 0.62mi Volume 1 cubic meter(m3) 1,000,000(106) cubic centimeters 35.2cubic feet (ft3) 1 ft3 = 0.0283m3 1 cubic decimeter (dm3) 1000cm3 0.2642 gallon (gal) 1.057 quarts (qt) 1 gal = 3.785 dm3 1 qt = 0.9464 dm3 1 cubic centimeter (cm3) 0.001 dm3 0.0338 fluid ounce 1 qt = 946.4 cm3 1 fluid ounce = 29.6 cm3 Mass 1 kilogram (kg) 1000 grams 2,205 pounds (lb) 1 (lb) = 0.4536 kg 1 gram (g) 1000 milligrams 0.03527 ounce(oz) 1 lb = 453.6 g 1 ounce = 28.35 g

  28. yotta Y 1024 zetta Z 1021 exa E 1018 peta P 1015 tera T 1012 giga G 1 000 000 000 109 mega M 1 000 000 106 kilo k 1000 103 hecto h 100 102 deka da 10 101 deci d 0.1 10-1 centi c 0.01 10-2 milli m 0.001 10-3 micro µ 0.000 001 10-6 nano n 0.000 000 001 10-9 pico p 10-12 femto f 10-15 atto a 10-18 zepto z 10-21 yocto y 10-24 There are 20 SI Prefixes:

  29. G 109 M 1 000 000 106 k 1 000 103 100 102 deka 10 101 base … 1 100 deci d 0.1 10-1 centi c 0.01 10-2 milli m 0.001 10-3 micro µ 0.000 001 10-6 nano n 0.000 000 001 10-9 1 000 000 000 giga mega kilo hecto h da

  30. “Give Meknowledgebrotherd.c. mun” Giga Mega kilo Base- g,m,L (great mr. Lincoln) deci centi milli u(=micro)nano

  31. 1000 cm = ______ mm 10.34 g = ______ kg 10.34 kg = ______ mg 3789.23 mm = ______ dm

  32. 93 cm = ______ Mm 3789.23 mL = ______ nL 3.78923 Gm = ______ dm

  33. Section 3.4 Density

  34. Example: Calculate the density of mercury if 1.00 x 102g occupies a volume of 7.36 cm3. m 1.00 x 102g = D = v 7.36 cm3 13.586 = 13.6 = 1.36 x 101 g/cm3

  35. 1st Semester Lecture Ends Here

  36. Example: A plastic ball has a density of .54 g/cm3. Will the plastic ball sink or float in a container of gasoline, .66 g/cm3. float

  37. Specific Gravity Specific gravity = density of substance density of water density of gold = 19.3 g/cm3= 19.3 density of water 1.000g/cm3

  38. Section3.5 Temperature

  39. A. Temperature scales Boiling pt. of water 212 F 100 C 373 K Freezing pt. of water 273 K 32 F 0 C Fahrenheit Celsius Kelvin Lowest temp possible all particlesmotion stops is O K or absolute zero. Common Temperature scale in U.S.

  40. http://www.212movie.com/ http://www.212movie.com/

  41. Equations for Temperature Conversions K = oC + 273 Memorize these equations!

  42. Normal body temp is 98.6 F. Convert to Celsius & Kelvin. K = C + 273 K = 37 + 273 K = 310 No degree sign! C = 37 o

  43. boiling point of water on Everest is343 K, what is this in Celsius? K = C + 273 343 = C + 273 343 - 273= C C = 70 o

  44. Dimensional Analysis – Get p. 16-17 ready uses units to solve problems & check answers. 1. Use equivalence statement to get conversion factor. 2. Pick conversion factor that cancels appropriate unit. 3. Multiply quantity by conversion factor. 4. Check Sig Figs. 5. Ask whether your answer makes sense.

  45. PROBLEM: What is the price of a piece of copper wire 325 centimeters (cm) long that sells for $0.15/ft? Sample Problem 1.2 Converting Units of Length

  46. in 2.54 cm 2.54 cm = 1 in = 128 in = 325 cm x

  47. Use the Unit cancelation Method. It’s easier 1 inch 2.54 cm 1 ft 12 inch $ 0.15 ft = 325 cm x

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