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Topic 1 Introduction_ Measurement_ Mathematical Operations

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					              Topic 1


    Introduction: Measurement,
Mathematical Operations; Introduction
           to Chemistry
Measurement
Measurement, from the Greek word
"metron", meaning limited proportion is
the estimation of the magnitude of
some attribute of an object, such as its
length or weight, relative to a unit of
measurement

It involves using a measuring
instrument, such as a ruler or scale,
which is calibrated to compare the
object to some standard, such as a
meter or a kilogram

Metrology is the scientific study of
measurement
Units of Measurements
Imperial system
        early used as English units then Imperial units
        came to known as US Customary Units
        have at times been called foot-pound-second systems

Metric System
        a decimalised system of measurement based on the
                 metre and the gram
        it has a single base unit for each physical quantity
        all other units are powers of ten or multiples of ten of this
        base unit

SI Units
           Système International d'Unités
           modern, revised form of the metric system
           two types of SI units, Base and Derived Units
SI Base Units
  Name      Symbol           Quantity

  metre       m               Length

 Kilogram     kg               mass

 second       s                time

 ampere       A           electric current

  kelvin      K      thermodynamic temperature

  mole       mol        amount of substance

 candela      cd         luminous intensity
                   SI Prefixes
yotta,   (Y),    meaning 1024   deci,    (d),   meaning 10-1
zetta,   (Z),    meaning 1021   centi,   (c),   meaning 10-2

exa,     (E),    meaning 1018   milli,   (m),   meaning 10-3

peta,    (P),    meaning 1015   micro,   (u),   meaning 10-6

tera,    (T),    meaning 1012   nano,    (n),   meaning 10-9

giga,    (G),    meaning 109    pico,    (p),   meaning 10-12

mega,    (M),    meaning 106    femto,   (f),   meaning 10-15

 kilo,   (k),    meaning 103    atto,    (a),   meaning 10-18

hecto,   (h),    meaning 102    zepto,   (z),   meaning 10-21

deka,    (da),   meaning 101    yocto,   (y),   meaning 10-24
Instruments used for measuring
Example

Convert the following measurements:

 1.   34 L = _____ cc
 2.   25°F = _____ °K
 3.   2.0 mg = _____ kg
 4.   3.5 hrs = ______ s
 5.   1 x 10-5 mol = ______ mol
Example

Convert the following measurements:
(Answer)
  1. 34 L = 34, 000cc
  2. 25°F = 244.48 °K
  3. 2.0 mg = 0.0000020 kg
  4. 3.5 hrs = 12600 s
  5. 1 x 10-5 mol = 0.01 mmol
     Basic Mathematical Operations
MDAS rule
  Perform multiplication/division first before
  addition and subtraction

e.g.
Solve the following:

1.    32(6+5) – 4/2 + (35+8)
2.    {3[4+8]/6} – (2+5(6)-12)
     Basic Mathematical Operations
MDAS rule
  Perform multiplication/division first before
  addition and subtraction

e.g.
Solve the following:

1.    32(6+5) – 4/2 + (35+8) = 393
2.    {3[4+8]/6} – (2+5(6)-12) = -14
         Rounding-off Figures
Rule 1: If the digit after that being retained is
  LESS than 5, the retained digit is unchanged.

Rule 2: If the digit after that being retained is
  GREATER than 5, the retained digit is
  increased by one.

Rule 3: f the digit after that being retained is
  EQUAL to 5, what follows determines how to
  round the number.
      If even number, retained
      If odd number, increase by 1
Example

Round to the nearest hundredths:

 1.   2.3560   =   _____
 2.   2.3460   =   _____
 3.   2.3452   =   _____
 4.   2.3453   =   _____
 5.   2.3423   =   _____
Example

Round to the nearest hundredths:
(Answer)
  1. 2.3560 = 2.36
  2. 2.3460 = 2.35
  3. 2.3452 = 2.34
  4. 2.3453 = 2.35
  5. 2.3423 = 2.34
Significant Figures
Guidelines for Using Significant Figures
1.  Any digit that is not zero is significant.
2.  Zeros between nonzero digits are significant.
3.  Zeros to the left of nonzero digit are not significant.
4.  If a number is greater than 1, all zeros written after the
    decimal point is significant.
5.  If a number is less than 1, zeros before the nonzero digit is
    not significant.
6.  For numbers that do not contain decimal point, the trailing
    zeros (zero after the nonzero digit) may or may not be
    significant.
7.  In addition and subtraction, the number of significant
    figures in the answer is determined by the digit that has the
    least number of decimal places.
8.  In multiplication and division, the number of significant
    figures in the product or quotient is determined by the
    original number that has the least number of significant
    figures.
Significant Figures
Example:

1.   5.01
2.   0.02120
3.   7,100
4.   7.10 x 103
5.   2.456
Significant Figures
Example:

1.   5.01 = 3
2.   0.02120 = 4
3.   7,100 = 2
4.   7.10 x 103 = 3
5.   2.456 = 4
Significant Figures
Example:

1.   12,524.1 + 0.1193
2.   8.60 x 2.1335
3.   0.0154 / 1.3
Significant Figures
Example:

1.   12,524.1 + 0.1193 = 12524.2
2.   8.60 x 2.1335 = 18.3
3.   0.0154 / 1.3 = 1.2 x 10-2
Scientific Notation

In observance of significant figures, scientist
  used scientific notation to express
  extremely large or small numerical values.
  All can be expressed in the form:


                N x 10n
Scientific Notation
Step 1: Find n

Step2: Count the number of places that the
  decimal point must be moved to give the
  number N.

Step 3: If the decimal point has to be
  moved to the left, n is a positive integer or
  to the right, n is a negative integer
Scientific Notation

Example:

1.   568213.5
2.   18162.07
3.   0.000092
Scientific Notation

Example:

1.   568213.5 = 5.682135 x 105
2.   18162.07 = 1.816207 x 104
3.   0.000092 = 9.2 x 10-5
      Accuracy and Precision

Accuracy     determines    how     close a
  measurement is to the true value of the
  quantity that is being measured.

Precision refers to the closeness of two or
  more measurements of the same quantity
  with one another.
                  Error
Error refers to a difference between actual
 behavior or measurement and the norms
 or expectations for the behavior or
 measurement

     Two types:
         1. Systematic Error (determinate)
         2. Random Error (indeterminate)
Error
               Chemistry

History
     began with the discovery of fire

     leads to the purification of metals
          (metallurgy)

     alchemy
                        Alchemy
Mission:
  protoscience

  to discover the elixir of
  life
  (fountain of youth)

  to create gold through
  transformation
                Alchemy

Failure:

  no scientific method
  unable to established nomenclature
  unable to reproduce experiments
              Timeline

First chemists – the Moslems
    Geber – the father of chemistry

Robert Boyle – alchemist turned chemist
  differentiate alchemy and chemistry

Antoine Lavoisier
                Timeline
Aristotle
    “atomos”

John Dalton

J. J. Thomson

Ernest Rutherford
                 Timeline

Chadwick

Niels Bohr

E. Schrodinger

Dmitriv Mendeleyeev
          Divisions of Chemistry
   Inorganic chemistry is the      study of the
    properties  and    reactions     of  inorganic
    compounds.

   Organic chemistry is the study of the structure,
    properties, composition, mechanisms, and
    reactions of organic compounds. In other words,
    it is the study of those substances that contain
    carbon.
             Divisions of Chemistry
   Analytical chemistry is the analysis of material samples
    to gain an understanding of their chemical
    composition and structure. Analytical chemistry
    incorporates standardized experimental methods in
    chemistry.

   Biochemistry is the study of the chemicals, chemical
    reactions and chemical interactions that take place in
    living organisms.

   Physical chemistry is the study of the physical basis of
    chemical systems and processes. In particular, the
    energetics and dynamics of such systems and
    processes are of interest to physical chemists.
          Divisions of Chemistry
Other subdivisions:

  Astrochemistry             Atmospheric chemistry
  Chemical Engineering       Chemo-informatics
  Electrochemistry           Environmental chemistry
  Geochemistry               Green chemistry
  History of chemistry       Materials science
  Medicinal chemistry        Molecular Biology
  Molecular genetics         Nanotechnology
  Organometallic chemistry   Petrochemistry
  Pharmacology               Photochemistry
  Phytochemistry             Polymer chemistry
  Supramolecular chemistry   Surface chemistry
  Thermochemistry            Theoretical Chemistry
  Nuclear Chemistry

				
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posted:10/29/2012
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