Dimensional_Analysis

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					                                       Dimensional Analysis
                                         Teacher’s Guide
                                          By: Rita Jones

Lesson Overview: The following lesson provides a     Subject area(s): Chemistry
powerpoint presentation to introduce the beginning
concepts of dimensional analysis.
National Science Education Standards Addressed:      Topic: Dimensional Analysis
    1. Dimensional Analysis
    2. Conversion factors
    3. SI Prefix Conversions                         Audience: 9th-12th grade


Resources:                                           Suggested time: 55 minutes
    1. Powerpoint inclusive
    2. Lemay, H. Eugene, Jr. Chemistry.
                                                     Materials:
        Prentice-Hall, Inc. 2002.
                                                         Powerpoint software
                                                         Calculators
                                                         SI prefix conversion table

Learning Objectives:
   1. Students will be able to perform dimensional analysis.
   2. Students will learn how to use SI prefix conversion tables properly.
   3. Students will apply learning to actual problems.

Background:
This is a fully prepared lesson plan which involves concept introduction and problems for
the students to work on individually. This allows the instructor to walk around the
classroom and help students who are struggling with the concept.

Assessment Strategy:
The format of this lesson allows the instructor to assess whether the students are grasping
the concept. If problems are seen in the students ability to work the problems
individually, the instructor can work on it with them individually, or go back to the power
point in order to reaffirm concepts.

Teaching tips:
Students must work problems individually in order to fully grasp concepts.
    Engage students by introducing concepts in the powerpoint and have students take
       notes on the information presented.
    Have students explore their understanding by completing each problem
       individually.
    Explain concepts by going through each problem as a group to make sure the
       student’s understanding is complete.

Extension(s):
Additional worksheet should be given to each student as homework.
    CH. 1--MEASUREMENT
              III.Unit Conversions
              (Sec. 1.7, pp. 38-47)




             Skills Check
   Multiplication of two integers
    with exponents.
    2 2 x 23 =
                 25
   Division of two integers with exponents.
    27   =

    23
                     24
                Problems
35 x 32
  34

                    33

42
45
                    1
                    43

                    4-3




       A. SI Prefix Conversions
   Use table on p. 937 to
    convert between
    prefixes.
   Subtract the
    exponents.
   Move the decimal that
    many places.
        A. SI Prefix Conversions

                           Prefix        Symbol   Factor
                           mega-
                           mega-         M        106
                           kilo-
                           kilo-         k        103
                           BASE          ---      100
                           UNIT
                           deci-
                           deci-         d        10-1
                           centi-
                           centi-        c        10-2
                           milli-
                           milli-        m        10-3
                           micro-
                           micro-        μ
                                         μ        10-6
                           nano-
                           nano-         n        10-9
                           pico-
                           pico-         p        10-12




          A. SI Prefix Conversions
                    page 18
   SI units for mass:
                                   grams (g)
   SI units for volume:
                                   liters (L)
   SI units for length:
                                   meters (m)
   SI units for time
                             seconds (s)
   SI units for temperature:
                             kelvin (K)
    *It is important to know that when labeling units, upper
    and lower case changes the meaning of the units.
      A. SI Prefix Conversions
   532 m = ? km




      A. SI Prefix Conversions
   1) 20 cm = __________ m

   2) 0.032 L = __________mL

   3) 45 μm = __________ nm
         μ




   4) 805 dm = __________ km
         B. Dimensional Analysis
   The technique of converting between units is
    called dimensional analysis.
         Factor- Label”
    The “Factor-Label” Method.
                 labels”                   factored”
        Units or “labels” are canceled, or “factored” out.

                       cm3 x g = g
                             cm3




         B. Dimensional Analysis
    Steps:
         1)   Identify starting & ending units.
         2)   Line up conversion factors so units cancel. (p.
              38 and p. 936).
         3)   Multiply all top numbers & divide by each bottom
              number.
         4)   Check units & answers.

                                              reasonable?”
         *Stop to ask yourself: “Is my answer reasonable?”
       B. Dimensional Analysis
   Lining up conversion
    factors:
             1 in    =1
             2.54 cm

             1 = 2.54 cm
                   1 in




       B. Dimensional Analysis
   1) Your European hairdresser wants to
    cut your hair 8.0 cm shorter? How many
    inches will he be cutting off? (See p. 38
    and p. 936)
     B. Dimensional Analysis
2) How many milliliters are in 1.00 quart of
  milk?




     B. Dimensional Analysis
3) Taft football needs 550 cm for a 1st
  down. How many yards is this?
       B. Dimensional Analysis
   4) You have 1.5 pounds of gold. Find its
    volume in cm3 if the density of gold is 19.3
    g/cm3.




       B. Dimensional Analysis
   5) How many liters of water would fill a
    container that measures 75.0 in3?
       B. Dimensional Analysis
6) A piece of wire is 1.3 m long. How many
  1.5-cm pieces can be cut from this wire?




       B. Dimensional Analysis
   Dimensional analysis can also be used to
    convert using metric prefixes and
    exponents:

    7) Convert 8470 s to μs.
                         μ
     B. Dimensional Analysis
8) Convert 6.85 nL to mL.




     B. Dimensional Analysis
9) If I was traveling down the interstate at
  71 mph, what would this be in cm/s?

				
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