Chemistry 1A

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Chemistry 1A

• Mr. Kimball
• dkimball_at_bakersfieldcollege.edu
• http//www2.bakersfieldcollege.edu/dkimball

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Welcome to Chemistry 2A

• Podcasts
• A little about myself
• A little about you
• New? Major? ESL? International?
• Learning Disorders
• Sign roll sheet
• Get phone numbers of others in class

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The Class Syllabus

• http//www2.bakersfieldcollege.edu/dkimball

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Some students prefer to skim through a course.
If you really want to succeed you need to go deep!
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Learning Skills

• Take Responsibility (its your education)
• Have Confidence (you can do it!)
• Dont Procrastinate (study for final now)
• Read/Listen Precisely (ignore things that just
  arent there)
• Practice (use practice tests)
• Persistence (get up one more time than you fall
  down)
• Recognize Patterns (most things are done the
  same way)
• Use Pictures (outline problem)
• Think Sequentially (one step at a time)
• Do Neat work (so you can check it)
• Group Study (explain things to each other)
• Try Something New (dont keep repeating
  failures)
• Get Help

R C P P P P P P S N G N H
Learning Skills Power Point
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Using This Book

• Concept check problems are found within the
  chapter with the solutions right there with the
  problem.
• Exercise problems are found within the chapter
  with select answers in the back of the book.
• Homework is assigned from the Internet. You
  should check the Eduspace link from my Main Web
  site under Chemistry 1a for instructions.

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Using This Book

• A CD comes with the book that has tutorials,
  practice quizzes and other aids. Those not doing
  well in the class should consider using some of
  these aids.
• There is also a web site. It has practice tests,
  flash cards, animations, etc.
• (http//college.hmco.com/chemistry/general/ebbing/
  general_chem/8e/students/index.html )

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Chemistry and Measurement
1.1 Modern Chemistry 1.2 Experiment and
Explanation 1.3 Law of Conservation of Mass 1.4
Matter
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Aristotle
Earth Air Fire Water
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Democritus (460-370 BC)

• Greek Philosopher who first coined the word
  atomos.

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What Is Chemistry?

• Chemistry is the study of the composition,
  structure, and properties of matter and energy
  and changes that matter undergoes.
• Matter is anything that occupies space and has
  mass.
• Energy is the ability to do work.

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Archimedes

• Archimedes lived in Syracuse on the island of
  Sicily.

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Archimedes

• A comparison of Archimedes Pulleys and Study!

Big Study!
Little Study!
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Galileo Galilei
Father of the Scientific Method
Heavy things fall faster than light
things???? Aristotle
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Experiment and Explanation

• Experiment and explanation are the heart of
  chemical research.
• An experiment is an observation of natural
  phenomena carried out in a controlled manner so
  that the results can be duplicated and rational
  conclusions obtained.
• After a series of experiments, a researcher may
  See some relationship or regularity in the
  results.

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Experiment and Explanation

• If the regularity or relationship is fundamental
  and we can state it simply, we call it a law.
• A law is a concise statement or mathematical
  equation about a fundamental relationship or
  regularity of nature.
• An example is the law of conservation of mass,
  which says that mass, or quantity of matter,
  remains constant during any chemical change.

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Experiment and Explanation

• Explanations help us organize knowledge and
  predict future events.
• A hypothesis is a tentative explanation of some
  regularity of nature.
• If a hypothesis successfully passes many tests,
  it becomes known as a theory.
• A theory is a tested explanation of basic natural
  phenomena.

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Experiment and Explanation

• The general process of advancing scientific
  knowledge through observation, laws, hypotheses,
  or theories is called the scientific method.

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The Scientific Method

• Examples
• Pons and Fleishman, Univ. of Utah.
• Horoscope
• Weather.

• Your Assignment
• Formulate a Problem.
• Observe and collect Data.
• Interpret Data.
• Test your Interpretation.

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Matter Physical State andChemical Constitution

• There are two principal ways of classifying
  matter
• By its physical state as a solid, liquid, or gas.
• By its chemical constitution as an element,
  compound, or mixture.

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Solids, Liquids, and Gases

• Solid the form of matter characterized by
  rigidity a solid is relatively incompressible
  and has a fixed shape and volume.
• Liquid the form of matter that is a relatively
  incompressible fluid liquid has a fixed volume
  but no fixed shape.
• Gas the form of matter that is an easily
  compressible fluid a given quantity of gas will
  fit into a container of almost any size in shape.

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Elements, Compounds, and Mixtures

• To understand how matter is classified by its
  chemical constitution we must first look at
  physical and chemical changes.
• A physical change is a change in the form of
  matter but not in its chemical identity.
• Physical changes are usually reversible.
• No new compounds are formed during a physical
  change.
• Melting ice is an example of a physical change.

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Elements, Compounds, and Mixtures (contd)

• A chemical change, or chemical reaction, is a
  change in which one or more kinds of matter are
  transformed into a new kind of matter or several
  new kinds of matter.
• Chemical changes are usually irreversible.
• New compounds are formed during a chemical
  change.
• The rusting of iron is an example of a chemical
  change.

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Elements, Compounds, and Mixtures (contd)

• A physical property is a characteristic that can
  be observed for material without changing its
  chemical identity.
• Examples are physical state (solid, liquid,or
  gas), melting point, and color.
• A chemical property is a characteristic of a
  material involving its chemical change.
• A chemical property of iron is its ability to
  react with oxygen to produce rust.

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Classification of Matter
Separate by Physical Processes-filtering-distill
ation-centrifuging
Separate by Chemical Processes-burning-fermentat
ion-rusting
Matter
Pure Substances
Mixtures
Compounds(molecules)
Homogeneous(solutions)
Heterogeneous(most things)
Elements(atoms)
Granite Sand Wood Orange Juice
Air Sodas Ocean Water Alcoholic drinks
Hydrogen Oxygen Copper Zinc
Water Alcohol Sugar Salt
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Separation by distillation.
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Elements sulfur, arsenic, iodine, magnesium,
bismuth, mercury. Photo courtesy of American
Color.
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A mixture of potassium dichromate and iron
fillings. Photo courtesy of James Scherer.
Return to slide 15.
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A magnet separates the iron filling from the
mixture. Photo courtesy of James Scherer.
Return to slide 15.
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(No Transcript)
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Chemistry and Measurement
1.5 Measurement and Significant Figures 1.6 SI
Units 1.7 Derived Units 1.8 Units and
Dimensional Analysis
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Measurement and Significant Figures

• Measurement is the comparison of a physical
  quantity to be measured with a unit of
  measurement -- that is, with a fixed standard of
  measurement.
• The term precision refers to the closeness of the
  set of values obtained from identical
  measurements of a quantity.
• Accuracy is a related term it refers to the
  closeness of a single measurements to its true
  value.

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Precision vs. Accuracy
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Measurement and Significant Figures (contd)

• To indicate the precision of a measured number
  (or result of calculations on measured numbers),
  we often use the concept of significant figures.
• Significant figures are those digits in a
  measured number (or result of the calculation
  with a measured number) that include all certain
  digits plus a final one having some uncertainty.

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Scientific Notation

• Useful with very large and very small numbers.
• Decimal always after first digit.
• Use x 10n where n is the number of decimal places
  you must move the decimal to get it just after
  the first digit.
• Positive exponents represent large numbers.
• 2,340,000,000,000,000 2.34 x 1015
• Negative exponents represent small numbers.
• 0.00000000000000234 2.34 x 10-15

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Measurement Accuracy

• How long is this steel rod?

There is no such thing as a totally accurate
measurement!
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Significant Figures

• Numbers that measure or contribute to our
  accuracy.
• The more significant figures we have the more
  accurate our measurement.
• Significant figures are determined by our
  measurement device or technique.

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Rules of Determining the Number of Significant
Figures

• 1. All non-zero digits are significant.

234 3 sig figs 1.333 4 sig figs
1,234.2 5 sig figs
2. All zeros between non-zero digits are
significant.
203 3 sig figs 1.003 4 sig figs
1,030.2 5 sig figs
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Rules of Determining the Number of Significant
Figures

• 3. All zeros to the right of the decimal and to
  the right of the last non-zero digit are
  significant.

2.30 3 sig figs 1.000 4 sig figs
3.4500 5 sig figs
4. All zeros to the left of the first non-zero
digit are NOT significant.
0.0200 3 sig figs 0.1220 4 sig figs
0.000000012210 5 sig figs
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Rules of Determining the Number of Significant
Figures

• Zeros to the right of the first non-zero digit
  and to the left of the decimal may or may not be
  significant. They must be written in scientific
  notation.

2300 2.3 x 103 or 2.30 x 103 or 2.300 x 103
2 sig figs 3 sig figs 4
sig figs
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Rules of Determining the Number of Significant
Figures

• 6. Some numbers have infinite significant
  figures or are exact numbers.

233 people 14 cats (unless in biology lab) 7
cars on the highway 36 schools in town
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How many significant figures are in each of the
following?

• 1) 23.34

4 significant figures
2) 21.003
5 significant figures
4 significant figures
3) .0003030
4) 210
2 or 3 significant figures
5) 200 students
infinite significant figures
1, 2, 3, or 4 significant figures
6) 3000
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Using Significant Figures in Calculations

• Addition and Subtraction

• Line up the decimals.
• Add or subtract.
• Round of to first full column.

23.345 14.5 0.523 ?
23.345 14.5 0.523 38.368
38.4 or three significant fingures
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Using Significant Figures in Calculations

• Multiplication and Division

• Do the multiplication or division.
• Round answer off to the same number of
  significant figures as the least number in the
  data.

(23.345)(14.5)(0.523) ?
177.0368075
177 or three significant figures
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Measurement in Chemistry
Length Mass Volume Time
meter gram Liter second
Km1000m Kg1000g KL1000L 1min60sec 100cm1m
1000mg1 g 1000mL1L 60min1hr 1000mm1m
SI System
Foot pound gallon second
British
12in1ft 16oz1 lb 4qt1gal (same) 3ft1yd 2000
lb1 ton 2pts1qt 5280ft1mile
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Table 1.5 Relationships of Some U.S. and Metric
Units
1 L 1.06 qt
1 lb 454 g
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Table 1.3 SI Prefixes
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Units Dimensional Analysis

• In performing numerical calculations, it is good
  practice to associate units with each quantity.
• The advantage of this approach is that the units
  for the answer will come out of the calculation.
• And, if you make an error in arranging factors in
  the calculation, it will be apparent because the
  final units will be nonsense.

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Unit Conversion

• Sodium hydrogen carbonate (baking soda) reacts
  with acidic materials such as vinegar to release
  carbon dioxide gas. Given an experiment calling
  for 0.348 kg of sodium hydrogen carbonate,
  express this mass in milligrams.

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Units Dimensional Analysis

• Dimensional analysis (or the factor-label method)
  is the method of calculation in which one carries
  along the units for quantities.

• Suppose you simply wish to convert 20 yards to
  feet.

• Note that the units have cancelled properly to
  give the final unit of feet.

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Units Dimensional Analysis

• The ratio (3 feet/1 yard) is called a conversion
  factor.
• The conversion-factor method may be used to
  convert any unit to another, provided a
  conversion equation exists.
• Relationships between certain U.S. units and
  metric units are given in Table 1.5.

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Unit Conversion

• Suppose you wish to convert 0.547 lb to grams.
• From Table 1.5, note that 1 lb 453.6 g, so the
  conversion factor from pounds to grams is 453.6
  g/1 lb. Therefore,

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Temperature

• The Celsius scale (formerly the Centigrade scale)
  is the temperature scale in general scientific
  use.
• However, the SI base unit of temperature is the
  kelvin (K), a unit based on the absolute
  temperature scale.
• The conversion from Celsius to Kelvin is simple
  since the two scales are simply offset by 273.15o.

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Figure 1.23 Comparison of Temperature Scales
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Temperature

• The Fahrenheit scale is at present the common
  temperature scale in the United States.
• The conversion of Fahrenheit to Celsius, and vice
  versa, can be accomplished with the following
  formulas

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Derived Units

• The SI unit for speed is meters per second, or
  m/s.
• This is an example of an SI derived unit, created
  by combining SI base units.
• Volume is defined as length cubed and has an SI
  unit of cubic meters (m3).
• Traditionally, chemists have used the liter (L),
  which is a unit of volume equal to one cubic
  decimeter.

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Derived Units

• The density of an object is its mass per unit
  volume,

where d is the density, m is the mass, and V is
the volume. Generally the unit of mass is the
gram. The unit of volume is the mL for liquids
cm3 for solids and L for gases.
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A Density Example

• A sample of the mineral galena (lead sulfide)
  weighs 12.4 g and has a volume of 1.64 cm3. What
  is the density of galena?