PreAP Chemistry

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Pre-AP Chemistry

• Summer Assignment 2007
• You will have a test over this material the
  Friday after we return to school.

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Metric Units The standards which are used to
define the SI units (Systeme International) which
we will use are
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Scientific Notation - an alternate way of writing
numbers, usually used with very large or very
small numbers

•             Scientific notation consists of TWO
  parts
  
•              (1)    a mantissa which is a
  positive or negative number between 1 and 10 
  (not including 10) all of the numbers within
  this range can be a mantissa, and the mantissa
  may be a whole number or a mixed number.
•          
•             (2)  a characteristic which is a
  whole number exponent to which the base 10 is
  raised. (given the number 103 This can also be
  written as 1.03 x 10 2)

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Correct scientific notation WILL ALWAYS HAVE BOTH
PARTS (a mantissa and a characteristic) EVEN IF
THE CHARACTERISTIC IS ZERO

• To convert a normal number to scientific
  notation, move the decimal either to the left or
  to the right until you have a mantissa whose
  absolute value is between 1 and 10 
• Count the number of places the decimal had to be
  moved and this is the characteristic. 
  
• To decide whether the characteristic is positive
  or negative, look at the original number--if it
  is smaller than 1, the characteristic will be
  negative if it is larger than 1, the
  characteristic will be positive. 
• REMEMBER THAT A POSITIVE CHARACTERISTIC MEANS
  THAT THE NUMBER IS A LARGE ONE AND A NEGATIVE
  CHARACTERISTIC MEANS THAT THE NUMBER IS A DECIMAL
  (SMALL) NUMBER.   

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Try converting these to scientific notation

• 1. 17600
• 2.  4.76
• 3.  0.00135         
• 4.  - 0.1544
• 5.  10.2
• 6.  301.0
• 7.  -67.30
• 8.  -0.000130

• Answers
• 1.76 x 104
• 4.76 x 100
• 1.35 x 10-3
• -1.544 x 10-1
• 1.02 x 101
• 3.01 x 102
• -6.73 x 101
• -1.3 x 10-4

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• To convert from a scientific notation to regular
  notation number
  
• A positive characteristic indicates the movement
  of the decimal place as many places to the right
  as are indicated.
  
• A negative characteristic indicates a movement of
  the decimal place the indicated number to the
  left and filling in the open spaces with zeroes.

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Try it the opposite way

• 1.  4.96 X 102
• 2.  7.01 X 100
• 3.  5.50 X 104
• 4.  5.61 X 10-3
• 5. -9.3 X 103
• 6. 4.92 X 102
• 7. -8.37 X 101
• 8. - 4.23 X 10-1

• Answers
• 496
• 7.01
• 55,000
• .00561
• -.0093
• 492
• -83.7
• -.423

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Multiplying and Dividing Scientific Notation

• GET YOURSELF A CALCULATOR, YOU WILL NEED ONE
  EVERYDAY OF CHEMISTRY, MAKE SURE IT IS A
  SICENTIFIC CALCULATOR!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  !!!!!!!!!!!!!!!!!!!!!!!!!!
• Numbers expressed in Scientific Notation can be
  multiplied and divided, if using a calculator
  always use parenthesis.
  
• When Multiplying, the mantissas should be
  multiplied and the exponents should be added. If
  the result is incorrect scientific notation then
  you should correct it.
• When dividing, the mantissa should be divided and
  the exponents should be subtracted, if the
  resulting answer is in incorrect scientific
  notation then it must be corrected.
• Examples Multiply the following numbers and
  express the answer in correct scientific
  notation
  
• ___6_x_101_________ 1. ( 2 X 104 ) (3 X 10-3)
• ___4_x_10-2________ 2. ( 8 X 10-5 )divided by (
  2 X 10-3)

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Try These

• Examples Multiply the following numbers and
  express the answer in correct scientific
  notation
  
• ___6_x_101_________ 1. ( 2 X 104 ) (3 X 10-3)
• _____________________ 2. ( 5 X 10-3 ) times ( 4
  X 10-4)
  
• _____________________ 3. ( 6 X 104 ) X ( -7 X
  10-5)
  
• _____________________ 4. ( -4.5 X 10-2 ) ( 2 X
  10-7)
  
• Perform the following divisions of scientific
  notation
  
• ____4_x_10-2___________1. ( 8 X 10-5 )divided by
  ( 2 X 10-3)
  
• ______________________2. divide ( 4 X 103 ) by (
  8 X 10-3)
  
• ______________________3. (6 X 10-7) / (3 X
  10-8)
  
• _____________________ 4. Divide 4.5 X 104 by
  9.0 X 10-12
  
• _____________ 5. Divide (2 X 103)(4 X 10-2) by
  (6 X 10-9)(4 X 105)

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answers

• Multiplying Scientific Notation
• 6 x 101
• 2.0 x 10-6
• -4.2 x 100
• -9 x 10 -9
• Dividing Scientific Notation
• 4 x 10-2
• 5 x 10-1
• 2 x 101
• 5.0 x 1015
• 3.33 x 104

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The Metric scale you have learned about follows
the first letters KHD b dcm

• You might have even made up a pneumonic for this
  sequence
  
• King Henry Died by drinking chocolate milk
• The sequence you must learn for chemistry is a
  little larger

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Expanded sequence

• Tera (T) 1 x 1012
• Giga(G) 1 x 109
• Mega(M) 1 x 106
• Kilo(K) 1 x 103
• Base 1
• deci(d) 1 x 10-1
• centi (c) 1 x 10-2
• milli(m) 1 x 10-3
• micro (µ) 1 x 10-6
• nano(n) 1 x 10-9
• pico(p) 1 10-12

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Metric Abbreviations

• What is the metric abbreviation for each of the
  following?
  
•  
•             _____   (a)  one-millionth of a
  gram                      _____   (b)  one
  thousand grams
  
•  
•             ____     (c)   one billion
  liters                               _____  
  (d)   one-thousandth of a meter
  
•  
•             ____     (e)  one-hundredth of a
  liter                     _____   (f)   one
  million grams
  
•  
• What is the metric abbreviation for each of the
  following?
  
•  
•             _____   (a)  1 X 103
  grams                                  _____  
  (b)  1 X 10-12  meters
  
•  
•             _____   (c)    1 X 106
  liters                                  _____  
  (d)   1/10 of a gram
  
•  
•             _____   (e)    1000
  meters                                  _____  
  (f)    1/1 000 000 000 of a liter)

• Answers
• a) µg b) Kg c) GL d) mm e) cL f)
  Mg
  
• a) Kg b) pm c) ML d) dg e) Km f)
  nL

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Metric to Metric

• You must be able to convert from one metric
  measurement to another.
  
• That might mean you memorize the stair-steps of
  the sequence and count the steps and move your
  decimal places accordingly either right or left
  depending on the movement

• Tera (T) 1 x 10-12
• Giga(G) 1 x 10-9
• Mega(M) 1 x 10-6
• Kilo(K) 1 x 10-3
• Base 1
• deci(d) 1 x 101
• centi (c) 1 x 102
• milli(m) 1 x 103
• micro (µ) 1 x 106
• nano(n) 1 x 109
• pico(p) 1 x 1012

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Try these problems using the stair step method.

• Example 1-26        Convert 378.4 cm to meters
•  
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• Example 1-27       Convert 4.32 X 10-4 g to
  micrograms
  
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• Example 1-28      How many picoliters are there
  in 4.56 X 10-7 liters?
  
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Try these next problems

•   Convert 5.43 GL to dL.
•    
•  
•  
•     Convert 6.99 X 108 pg to cg.
•  
•  
•  
•    How many micrometers are there in 45.2
  kilometers?

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answers

• Metric to Metric conversions
• 3.784 m
• 432 µg or 4.32x102µg
• 4.56 x 105pL
• 88,100 m
• More Metric to Metric conversions
• 5.43 x 1010 dL
• 6.99 X 1015 cg
• 4.52 x 1010 µm