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Biochemistry 2012 2013

Biochemistry 2012 2013. Unit 1 K Timberlake Chemistry (blue text). Big Topics Unit 1. Metric system versus English system (day 2) Metric prefixes (day 4--6) Converting between metric units (Day 5, 6) Scientific notation (day 3) Measuring using significant digits (day 4)

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Biochemistry 2012 2013

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  1. Biochemistry 2012 2013 • Unit 1 K Timberlake Chemistry (blue text)

  2. Big Topics Unit 1 • Metric system versus English system (day 2) • Metric prefixes (day 4--6) • Converting between metric units (Day 5, 6) • Scientific notation (day 3) • Measuring using significant digits (day 4) • % error calculations (day 5—7) • Converting between one unit and another—Dimensional analysis (days 7—8)

  3. Learning goals and achievment criteria (objectives)

  4. Level 2.0 Know basic terms, definitions, concepts or examples. (memorize, write definitions, identify, match, list, fill blank) i. Convert between decimal numbers or fractions and exponential numbers into scientific notation (e.g., 1 x 10-1 =1/10 = 0.1). • Know the names and symbols for standard metric units of length, volume, mass, & time. • Memorize the definitions for the metric prefixes kilo, centi, milli, and micro • Memorize the mneumonic for the order and relative sizes of the metric prefixes, Kilo- through micro-. • Know the rules for writing significant digits and record # significant digits in a number. • Assess the precision and accuracy of lab equipment. • Identify conversion factors for two equal values • Know the formula for %error

  5. Level 3.0 Know & apply information from level 2.0 to achieve the learning goal. • Use the metric prefix mneumonic to write conversion factor equations that could be used for converting from one metric unit to any other. • Use the metric prefix mneumonic to carry out the conversion of measurements from one metric unit to another metric unit without using a calculator (length  length, volume volume, timetime, massmass) • Be able to complete one step dimensional analysis conversions for any measurements. (e.g, metric to english system lengths) • Measure quantities, then report the answer in scientific notation with the correct # significant digits and the correct units. • Count the # of significant digits in a number, or round a number to a certain # significant digits • Find the %error in a measurement • Explain the importance of a measurement’s # significant digits and the % error in the measurement. Level 4.0 Show greater depth of understanding than specifically taught. • Use the metric prefix mneumonic to write in your own words—or describe with a novel diagram—a rule for using the mneumonic to convert from one metric unit to another. ii. Be able to complete two or more step dimensional analysis conversions for any measurements, and be able to work with compound units (e.g., convert 3 miles/hr to micrometers/s)

  6. August 21 Day 1 Learning objective: Students will be able to distinguish metric and English system units of measurements, and they will know the symbols and names for metric units of length, time, volume, and mass. Homework: all four questions in the blue box at the end of section 1.1

  7. Timberlake chapter 1.2 Metric versus British units: Scientists use Metric (and so does every general population except that of the U.S.) Type measure metric SI unitBritish units Length meter (m) foot (ft or ‘) volume liter (L) quart (qt) time second (s) hour (hr) mass kilogram (kg) pound (lb or #)

  8. August 22 Day 2Timberlake 1.2 Learning objective Students will be able to convert numbers from decimal, expanded format to a format showing the size of a number with exponents of 10. e.g., 0.000006 m = 6 x 10-6m Homework: problems in blue box at end of section 1.2—quiz day 3 end of class on 1.1, 1.2

  9. Chapter 1.2 scientific notation Scientists make very large or very small measurements. To show size of a measurement without writing many zero’s before & after the decimal point, use scientific notation. 1,000,000 g = 1 x 106 g = 1 e 6 g 0.0000045 m = 4.5 x 10-6 m = 4.5 e -6 m 310,000 s = 3.1 x 105 s = 3.1 e 5 s

  10. The rule for scientific notation #.#...# X 10□ one number left of decimal point, use of an exponent of 10 number digits right of the decimal depends upon accuracy & precision of equipment used in making measurements

  11. How big? How small? Scientific notation Significant Digits How accurate & precise?

  12. Scientific notation Scientific notation is the form #.#...# X 10□ Decimal notation Scientific notation 127 m 1.27 x 102 m 0.0907 l 9.07 x 10–2 l 0.000506 s 5.06 x 10–4 s 2 300 000 000 000 g 2.3 x 1012 g

  13. 3 Which number in scientific notation matches 0.0006789? • 678.9 • 6.789 x 10-4 • 6.789 x 104 • 6.789

  14. Day 3 lab: Measure the mass of the thumb tack on all 11 marked balances. Record your answers in scientific notation.

  15. Mass of the thumb tack in grams Analytical balances (g) Scientific notation (g) • 0.540 5.40 x 10-1 g • 0.540 5.40 x 10-1 g • Triple beam balances • 0.56 5.6 x 10-1 g • 0.55 5.5 x 10-1 g Spring balances 5. 6. 7 no change…equipment won’t work for very light objects 0.1 g electronic balances • 0.54 5.4 x 10-1 g • 0.54 5.4 x 10-1 g 0.01 g electronic balances • 0.5 5. x 10-1 g • 0.5 5. x 10-1 g

  16. Day 4 August 24 section 1.3 Learning objective: Students will understand how to use significant digits to show the accuracy and precision of measurements, and they will be able to round a calculated value to the correct number of significant digits.

  17. Precision is the range of error due to how similar (closely grouped or far scattered) measures are: Inaccurate accurate Precise precise Inaccurate more accurate More precise less precise

  18. In lab, it’s better to use a less accurate (with error size known) and more precise instrument than more accurate but less precise instrument. If a scale reliably (precisely) measures 2.3 g light, then I can always add 2.3 g to my recorded measurements!

  19. Scientific notation shows the size of a measurement without the need for “placeholder” zeros Recording measurements in both Scientific notation and with the correct number of significant figures (significant digits, sig figs) reveals how your certainty in the accuracy of your measurement. All “places” (e.g., one’s place, tenth’s place, one-hundreth’s place) are shown, along with the “place” of the first estimated (floating) digit

  20. Why are significant figures important to scientists? The number digits recorded shows the reader the certainty that the author has in the measurement. It dictates the choice of equipment needed to get a similarly accurate result.

  21. Timberlake chapter 1.3 • Significant digits • Significant digits show others how precise and accurate your measurements are • Exact #s (like counting 16 people in our class) have unlimited significant digits, so in calculations with exact numbers, the other measurements in the experiment set how many digits to use.

  22. Counting #s (like 5 people) or definitions (like 1000 g = 1 kg) should not be used to determine #s sig figs If a number is a measurement, but decimals are not recorded, then only count the nonzero digits and the zeros between the nonzero digits. e.g., 300 feet 1 sig fig 320 feet 2 sig figs 300. feet 3 sig figs 320. feet 3 sig figs 320.0 feet 4 sig figs

  23. What is the # sign figs in each? 3 4 3 2 1 4 4 6 Infinite 5 • 2.83 • 36.77 • 14.0 • 0.0033 • 0.02 • 0.2410 • 2.350 x 10–2 • 1.00009 • 3 (!or 1) • 0.0056040

  24. Rules for counting significant digits & writing #’s with the correct # significant digits (also called significant figures—sig figs) • Include all digits that are known for sure • Include the first rounded (estimated) digit • Count these numbers: --All nonzero digits recorded -- All zeros to the right of any nonzero—provided that a decimal point is shown --All zeros between nonzero’s

  25. Mass of the thumb tack in grams Analytical balances (g) Scientific notation (g) Sign digits • 0.540 5.40 x 10-1 g 3 • 0.540 5.40 x 10-1 g 3 • Triple beam balances • 0.56 5.6 x 10-1 g 2 • 0.55 5.5 x 10-1 g 2 Spring balances 5. 6. 7 no change…equipment won’t work for very light objects 0.1 g electronic balances • 0.54 5.4 x 10-1 g 2 • 0.54 5.4 x 10-1 g 2 0.01 g electronic balances • 0.5 5. x 10-1 g 1 • 0.5 5. x 10-1 g 1

  26. Rules for counting significant digits & writing #’s with the correct # significant digits (also called significant figures—sig figs) • Include all digits that are known for sure • Include the first rounded (estimated) digit • Count these numbers: --All nonzero digits recorded -- All zeros to the right of any nonzero—provided that a decimal point is shown --All zeros between nonzero’s

  27. Write this measurement scientifically, using both scientific notation and significant digits. 110 ml rough measurement 1.1 x 10 2 ml Measurement with two significant figures (I know that the measurement is between 100 and 120 ml, but I estimated the 10’s of ml’s measurement.) http://images.google.com/imgres?imgurl=http://web.mac.com/scifione/orig/LABWARE/LAB-GIFS/Graduated-cylinder.gif&imgrefurl=http://web.mac.com/scifione/orig/LABWARE/Lab-alpha.htm&usg=__dd7_xfPrtTskzh2C66HHAgNWtBg=&h=593&w=260&sz=13&hl=en&start=1&um=1&tbnid=GsvNSG3sOiqBRM:&tbnh=135&tbnw=59&prev=/images%3Fq%3Dgraduated%2Bcylinder%26hl%3Den%26rlz%3D1T4SUNA_enUS312US211%26sa%3DN%26um%3D1

  28. r Nonscientific reading: 43 ml With two significant figures: 4.3 e 1 ml I’m sure of the 10’s place, but the one’s place is an estimate • http://images.google.com/imgres?imgurl=http://web.mac.com/scifione/orig/LABWARE/LAB-GIFS/Graduated-cylinder.gif&imgrefurl=http://web.mac.com/scifione/orig/LABWARE/Lab-alpha.htm&usg=__dd7_xfPrtTskzh2C66HHAgNWtBg=&h=593&w=260&sz=13&hl=en&start=1&um=1&tbnid=GsvNSG3sOiqBRM:&tbnh=135&tbnw=59&prev=/images%3Fq%3Dgraduated%2Bcylinder%26hl%3Den%26rlz%3D1T4SUNA_enUS312US211%26sa%3DN%26um%3D1

  29. What is this measurement, stated in scientific notation with correct significant figures? 5.59 e 1 ml 5.59 x 101ml Why? I know for certain that the measurement falls between 55 & 56 ml, but I’m not sure it’s 55.9 or 56.0 ml. ritter.tea.state.tx.us

  30. Do you see why my best estimate for this volume is 6.35 ml, a measurement with 3 significant digits? Writing x 10o is not necessary. geoscience.stevekluge.com

  31. Day 4 lab—recording volume measurements with the correct # significant digits AND using water to calibrate balances. 1 13mm diameter test tube full of water was added to each volume measuring device. As carefully as you can find the volume in each container. 50 ml beaker ______ 10 ml graduated cylinder ___________ 100 ml graduated cylinder ______________ Find the mass of the tube filled with water, the expected volume in g since 1.000g water = 1.000 ml water _______

  32. Rules for counting significant digits & writing #’s with the correct # significant digits (also called significant figures—sig figs) • Include all digits that are known for sure • Include the first rounded (estimated) digit • Count these numbers: --All nonzero digits recorded -- All zeros to the right of any nonzero—provided that a decimal point is shown --All zeros between nonzero’s

  33. Water can be used to calibrate balances, provided that you have a very accurate volume measuring device (like a micropipet) 1.00 ml water = 1.00 g water

  34. Mass of water can be used to calibrate volume measuring instruments if you have available a balance with a reliable standard mass, high accuracy, and high precision. Place the volume measuring device on the balance, then “tare” or “rezero” the balance. Carefully add pure water up to a well visible mark on the device. Compare the mass in g to the volume in ml:

  35. Calibrating a graduated cylinder by water mass If the 6.62 e1 ml reading matches mass 6.52 e1 g for water, then use 2 significant digits: 6.6 e 1 ml, because the accuracy of the device is not likely greater than the 10’s of a ml. If no mass standard is known, just record the 3 sign figs. Often, instruments will say +/- 2% (e.g.) http://chemsrvr2.fullerton.edu/HES/volume/volume_files/meniscus.gif

  36. Share data with classmates, then find the average volume for each measurement and find the % error in each volume measuring device.

  37. 8 27 2012 day 5Learning objective By using the metric pneumonic, convert between metric units WITHOUT using a calculator!

  38. Metric prefixes allow large and small measurements to be described micro (µ) 1/1 millionth 0.000001 e.g, 4 µm 4 micrometers= 0.000004 m milli (m) 1/1 thousandth 0.001 e.g., 3.4 milliseconds = 3.4 ms = 0.0034 s centi (c) 1/100 0.01 e.g., 72 centigrams = 0.72 g kilo (k) 1000 e.g., 45 kiloliters = 45,000 L

  39. King Henry Died Unexpectedly drinking chocolate milk ▬ ▬ µKilo- Hecta- Deca- unit deci- centi- milli ▬ ▬ micro- For each position separating units in the mneumonic, the size of 1 unit increases by one order of magnitude with each movement left; the size decreases by one order of magnitude with each movement right. So Know 1Ksneed to know #Hs (move one position right to the unknown) How many Hs are in 1 Ks? 1 Ks = 10 Hs = 1 x 101 Hs this means that a Ks is 10 times bigger than a Hs How many Ks are in 1 Hs? 1 Hs = 0.1 Ks = 1 x 10-1 Ks this means that Hs is 10 times smaller than a Ks

  40. King Henry Died Unexpectedly Drinking Chocolate Milk ▬ ▬ µKilo- Hecta- Deca- unit deci- centi- milli ▬ ▬ micro-given (starting) unit new (ending) unit 10 X bigger per movement rightnew unit given unit 10X smaller per movement left ? Km =1 Dm move 2 positions left from the given value of 1 Dm, so from 1 x 100 1X 10-11X10-2 1 Dm = 0.001 Km = 1 x 10-2Km =0.01 Km ? ml = 1 Hl move 5 positions right from given value to unknown 1x100 1X10+11X10+2 1X10+31X10+4 1X10+5 1 Hl = 1 x 105 ml = 10,000 ml

  41. King Henry Died Unexpectedly Drinking Chocolate Milk ▬ ▬ µKilo- Hecta- Deca- unit deci- centi- milli ▬ ▬ micro- unknown given (answer smaller than 1, exponent of 10 negative) unknown given (answer larger than 1, exponent of 10 positive)Multiply the given value by the difference in size of the units! ? Km =15 Dm move 2 positions left from given value of 15 Dm 15 x 10o Dm15 x 10-1Hm15 x 10-2Km 15 Dm = 15 x 10-2Km =0.15 Km 15 Dm = 15 (1 x 10-2Km ) = 0.15 Km ? ml = 0.09 Hl move 5 positions right from given value to unknown 0.09 x10o Hl0.09x101 Dl 0.09 x102 l 0.09 x103 dl0.09 x104cl0.09 x105ml 1 Hl = 1 x 105 ml = 10,000 ml 0.09Hl=0.09(1 x 105ml)=9 x 10-2(1 x 105ml)= 9 x 103ml =9000ml

  42. King Henry Died Unexpectedly Drinking Chocolate Milk ▬ ▬ µKilo- hecta- deca- unit deci- centi- milli ▬ ▬ micro- Level 2.0 iii, iv self assessment Memorize the definitions for the metric prefixes kilo, centi, milli, and micro ? Meters in one kilometer? __________ ?Centiliters in one liter? ___________ ?Microseconds in one second? __________ ?Grams in 1 microgram? ___________

  43. King Henry Died Unexpectedly Drinking Chocolate Milk ▬ ▬ µKilo- hecta- deca- unit deci- centi- milli ▬ ▬ micro- Level 3.0 i self assessment Use the metric prefix mneumonic to develop conversion factors for converting from one metric unit to any other 1 Km = 1x103 m or 1 deciliter = 1x101cl ? Meters in 1 Hm __________ ?Centiliters in one kiloliter ___________ ?Microseconds in one millisecond __________ ?Grams in 1 decigram ___________

  44. King Henry Died Unexpectedly Drinking Chocolate Milk ▬ ▬ µKilo- hecta- deca- unit deci- centi- milli ▬ ▬ micro- Level 3.0 ii self assessments Use the metric prefix mneumonic to convert measurements from one metric unit to another ? Meters in 15 Km __________ ?Centiliters in 1 x 10-6 kiloliter ___________ ?Milliseconds in 23 microseconds __________ ?micrograms in 1 decigram ___________

  45. 1 Arrange smallest to largest: 20 km, 20mm, 20µm, 20dm, 20m,20 cm • 20 km, 20mm, 20µm, 20dm, 20m,20 cm • 20 km, 20 m, 20 dm, 20 cm, 20 mm, 20 µm • 20 µm, 20 mm, 20 cm 20 dm, 20 m, 20 km

  46. 2 Which is the same as 327 µm? • 0.327 m • 0.0327 m • 327 x 10 -6 m • 3.27 x 10 -4 m • 3.27 x 10 3 m • Both 3 and 4

  47. King Henry Died Unexpectedly Drinking Chocolate Milk ▬ ▬ µKilo- hecta- deca- unit deci- centi- milli ▬ ▬ micro- Level 4.0 i self-assessment Use the metric prefix mneumonic to write in your own words—or describe with a novel diagram—a rule for using the mneumonic to convert from one metric unit to another and explain how to use it in a memorable way. ______________________________________________________________________________________________________________________________________________________

  48. Day 7 Unit conversions Aug 29

  49. If apples cost $1.50 per kilogram, then how many kilograms can you buy if you have $10? Given value ______________ Given value units _______________ Needed value units _______________ Useful conversion factor (equal value) ________ Set up ______________ Answer _____________

  50. Level 3.0 iiiBe able to complete one step dimensional analysis conversions for any measurements. General format for unit conversion (also called dimensional analysis) • Given value the originally given quantity whose units of measurement need to be converted • Needed value the same quantity expressed in the new units • Giving unit • Needed unit • Conversion factor • a fraction whose denominator and numerator have the same value (equivalent value), even though the units of measure are different 10 dimes = 1 $ 1 $/10 dimes 10 dimes/1 $

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