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Conversions Significant Digits Rounding

Conversions Significant Digits Rounding. Significant Digits. Significant Digits. What is the definition of significant? How is “Digit” used in this phrase?. Significant Digits Can be:. N onzero digits 654 Z eros between nonzero digits 6042

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Conversions Significant Digits Rounding

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  1. Conversions Significant DigitsRounding

  2. Significant Digits

  3. Significant Digits • What is the definition of significant? • How is “Digit” used in this phrase?

  4. Significant Digits Can be: • Nonzero digits 654 • Zeros between nonzero digits 6042 • Zeros to the right of a nonzero digit and to the left of a decimal 4230. • Zeros to the right of a nonzero digit and to the right of a decimal 0.30

  5. Digits That are Never Significant: • Zeros to the left of decimal in values less than one 0.82 • Zeros to the right of decimal and to the left of the first nonzero digit 0.082

  6. Significant Digits Exceptions • Exact Conversion factors are considered to have unlimited significant digits 1000 mm = 1 m • Counting numbers have unlimited sig digs 6 doughnuts

  7. Significant Digits Practice • How many significant digits? • 1044 (4) • 10 (1) • 10. (2) • 0.10 (2) • 130 (2) • 1040 (3) • 0.12 (2) • 1060220 (6) • 0.3000 (4) • 1040. (4)

  8. Scientific Notation Why do we use an elevator? Why is a fax machine an office requirement? Why do we drive a car to work? Which is faster, a whisk or a blender? Why do we use a microwave oven?

  9. Scientific Notation Why should you use scientific notation? When should you use scientific notation?

  10. Avagadro’s Number • 602200000000000000000000 • This number represents the number of molecules in one “MOLE” of material. BUT • You have to know the formula of the material. • 602000000000000000000000 • Write it five times!

  11. Avagadro’s Number • 602000000000000000000000 • Want to write it five more times? • Lets write it again like this: • 6.022 X 1023 • This is called scientific notation. • Write this one five times! • Which would you rather write? • WHY?

  12. Adding or Subtracting with Sci. Not. • 6.022 x 1023 + 4.522 x 1022 • These numbers cannot be added as written. • The exponents must be the same in order to add or subtract. • = 6.022 x 1023 + 0.4522 x 1023 • = 6.474 x 1023

  13. Multiplyingwith Sci. Not. • 6.022 x 1023 x 2.37 x 1022

  14. Situation • I’m making omelets for a bunch of people. I need a lot of eggs. • What is “a dozen” eggs? • Express a dozen eggs in scientific notation: • 1.2 X 101 • Can you think of two mathematical ways to express TWO dozen eggs (use scientific notation)? • 2 x (1.2 X 101) • (1.2 X 101) + (1.2 X 101)

  15. To Remember about SciNot • Properly expressed, a SciNot value will have one nonzero digit to the left of the decimal. • In converting to SciNot: • 165467 • For each place you move the decimal left, increase the exponent by 1 • = 1.65467 X 105 (6 Significant Digits) • In converting to SciNot: • 0.00002350 • For each place you move the decimal right, decrease the exponent by 1 • = 2.350 X 10-5 (4 Significant Digits)

  16. Conversions • The language of chemistry is mathematical and verbal. • The typical measurement system of chemistry is the SI system. • Length = Meters (m) • Mass = Grams (g) • Volume = Liters (L) • Temperature = Kelvins (k) or degrees celsius °C • Pressure = Pascals (Pa) or Atmospheres (atm) • There are more conversions that we will cover later.

  17. Conversions - II • Metric conversions – Remember this acronym: • KHDmdcm g L King Hector Died monday drinking chocolate milk Use this acronym when converting from one metric unit to another metric unit.

  18. Conversions - III • Example: • Convert 650 mL (milliliters) to L Liters K H D (L) d c m K H D (L) d c m You have to move 3 places left. Since you have to Jump 3 places to the left, move the decimal point 3 digits to the left. 6 5 0 . = 0.650 L

  19. Conversions - IV • Example II: • Convert 7.25 Km (Kilometers) to m (meters) K H D (m) d c m K H D (L) d c m You have to move 3 places right. Since you have to Jump 3 places to the right, move the decimal point 3 digits to the right and add a zero. 7 . 2 5 0 . = 7250. m

  20. Conversions - V • Try! Convert 72.5 g to mg • Answer: 72,500 mg • Try one more: Convert 26 HL to dL • Answer: 26,000 dL

  21. Conversions - Practice • Convert 65 mg to g • How many Decagrams are in 5 grams? • How many kilograms are in 7588 grams? • How many deciliters are in 2.7 liters? • How many km are in 102,000 cm?

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