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 What is the definition of significant?  How is “Digit” used in this phrase?

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Presentation on theme: " What is the definition of significant?  How is “Digit” used in this phrase?"— Presentation transcript:

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3  What is the definition of significant?  How is “Digit” used in this phrase?

4  Nonzero digits 654  Zeros between nonzero digits 6042  Zeros to the right of a nonzero digit and to the left of a decimal  Zeros to the right of a nonzero digit and to the right of a decimal 0.30

5  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  Exact Conversion factors are considered to have unlimited significant digits 1000 mm = 1 m  Counting numbers have unlimited sig digs 6 doughnuts

7  How many significant digits? ◦ 1044(4) ◦ 10(1) ◦ 10. (2) ◦ 0.10(2) ◦ 130(2) ◦ 1040(3) ◦ 0.12(2) ◦ (6) ◦ (4) ◦ (4)

8 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 Why should you use scientific notation? When should you use scientific notation?

10   This number represents the number of molecules in one “MOLE” of material. BUT ◦ You have to know the formula of the material.  ◦ Write it five times!

11   Want to write it five more times?  Lets write it again like this: ◦ X ◦ This is called scientific notation. ◦ Write this one five times!  Which would you rather write?  WHY?

12  What do you notice about this number? ◦ One number to the left of the decimal ◦ This is called scientific notation. ◦ x is NOT scientific notation  How do you punch Avogadro's number into a calculator? WARNING, it varies.

13  x x ◦ These numbers cannot be added as written. ◦ The exponents must be the same in order to add or subtract.  = x x  = x 10 23

14  x x 2.37 x 10 22

15  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 10 1  Can you think of two mathematical ways to express TWO dozen eggs (use scientific notation)? ◦ 2 x (1.2 X 10 1 ) ◦ (1.2 X 10 1 ) + (1.2 X 10 1 )

16  Properly expressed, a SciNot value will have one nonzero digit to the left of the decimal.  In converting to SciNot: ◦ ◦ For each place you move the decimal left, increase the exponent by 1 ◦ = X 10 5 (6 Significant Digits)  In converting to SciNot: ◦ ◦ For each place you move the decimal right, decrease the exponent by 1 ◦ = X (4 Significant Digits)

17  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.

18  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.

19  Example: ◦ Convert 650 mL (milliliters) to L Liters K H D (L) d c m Since you have to Jump 3 places to the left, move the decimal point 3 digits to the left. You have to move 3 places left = L

20  Example II: ◦ Convert 7.25 Km (Kilometers) to m (meters) K H D (m) d c m K H D (L) d c m Since you have to Jump 3 places to the right, move the decimal point 3 digits to the right and add a zero. You have to move 3 places right = m

21  Try! Convert 72.5 g to mg  Answer: 72,500 mg  Try one more: Convert 26 HL to dL  Answer: 26,000 dL

22 1. Convert 65 mg to g 2. How many Decagrams are in 5 grams? 3. How many kilograms are in 7588 grams? 4. How many deciliters are in 2.7 liters? 5. How many km are in 102,000 cm?


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