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Chapter 1�

Introduction to Chemistry

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Problem/Question

Observation/Research

Formulate a Hypothesis

Experiment

Collect and Analyze Results

Conclusion

Modify

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Scientific Method

  • A way of solving problems or answering questions.
  • Starts with observation- noting an recording facts
  • Hypothesis- a possible explanation as to the cause of the observation, based on research and previous knowledge

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Scientific Method

  • Experiment- designed to test the hypothesis
  • only two possible answers
    • hypothesis is right
    • hypothesis is wrong
  • Generates data -observations from experiments.
  • Modify hypothesis - repeat the cycle

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  • Cycle repeats many times.
  • By you and by others
  • The hypothesis gets more and more certain.
  • Becomes a theory
  • A thoroughly tested model that explains why things behave a certain way.

Observations

Hypothesis

Experiment

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  • Theory can never be proven.
  • It is the best explanation
  • Useful because they predict behavior
  • Help us form mental pictures of processes (models)

Observations

Hypothesis

Experiment

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  • Another outcome is that certain behavior is repeated many times
  • Scientific Law is developed
  • Description of how things behave
  • Usually an equation
  • Law - how
  • Theory- why

Observations

Hypothesis

Experiment

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Prediction

Experiment

Modify

Observations

Hypothesis

Experiment

Law

Theory

(Model)

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Variables

  • Controlled experiment- Only want one thing to change at a time in a laboratory.
  • Manipulated variable- What you change or control directly
  • Also called independent variable
  • Responding variable – What changes as a result. No direct control
  • Also called dependent variable

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What is Chemistry?

  • The study of the matter, its composition, properties, and the changes it undergoes.
  • Applied chemistry is the using chemistry to attain certain goals, in fields like medicine, agriculture, and manufacturing
  • Pure chemistry gathers knowledge for knowledge’s sake

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Which Comes First?

  • Pure Chemistry

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Usually comes first, applied later

Called technology

Or engineering

Pure chemistry can explain behavior that has been used without knowing why

Steel swords

  • Applied Chemistry

Can’t be good or �bad

Can be good or bad depending on use

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Branches of Chemistry

  • Analytical Chemistry -studies composition of substances.
  • Organic Chemistry -compounds containing carbon
  • Inorganic Chemistry -substances without carbon
  • Biochemistry- Chemistry of living things
  • Physical Chemistry studies behavior of substances
    • rates and mechanisms of reactions
    • energy transfers

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Why study Chemistry

  • Explain the natural world
    • Why?
  • Prepare for a career
    • Directly- in a lab
    • Indirectly- problem solving and thinking skills
  • Be an informed citizen
    • Vote
    • Don’t get scammed

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Communication

  • Use Journals
    • Do research
    • Write article
      • Describe procedures,� methods, and findings
    • Submit for peer review
      • Sent back for editing
    • Publish
      • Letters to editor �respond.

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Collaboration

  • Working together
  • Teams
    • Different skills
    • Different specialties
  • Internet and Email
  • Conferences

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Problem Solving

  • Only way to get good is to practice
  • Two parts
    • Developing Plan-
      • Hard part
      • Higher level thinking
    • Implementing Plan-
      • Not so hard
      • Application level

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Solving Numeric Problems

  • Three steps-
    1. Analyze
      • Plan
        • The heart of problem solving
        • Diagram
        • Look info
          • Table
          • Graph
          • Equation

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Solving Numeric Problems

  • Three steps-
    1. Analyze
      • Known
        • Numbers
        • Measurements
        • Equations
      • Unknown
        • What are you looking for?
        • What units?

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Solving Numeric Problems

  • Three steps-
    1. Analyze
    2. Calculate
      • Easiest part
      • Convert measurements
      • Rearrange
      • Appendix C

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Solving Numeric Problems

  • Three steps-
    1. Analyze
    2. Calculate
    3. Evaluate
      • Reasonable?
      • Read the question, did you answer it?
      • Check your work
      • Estimate

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Practice

  • What is the length, in centimeters, of a 10.0-inch ruler, given that there are 2.54 centimeters per inch?

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Practice

  • A certain ball when dropped from any height, bounces one-half the original height. If the ball was dropped from a height of 60 in. and allowed to bounce freely, what is the total distance the ball has traveled when it hits the ground for the third time? Assume the ball bounces straight up and down.

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Conceptual Problems

  • Without numbers or math
  • Two steps
    1. Analyze
      • Identify known and unknown
      • Plan
    2. Solve

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Practice

  • You find a sealed box �with strings protruding �from three holes, as �shown in the diagram. �When you tug string A, it becomes longer and string C becomes shorter. When you tug string B, it becomes longer, but strings A and C are not affected. Make a diagram showing the arrangement of the strings inside the box.

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Oreo Lab

  • In your lab groups, you will be given four regular and four double stuft Oreos. Come up with a lab to prove whether it is actually double or not.
  • Create a procedure, data table, calculations and a conclusion statement. Remember reproducibility is key to scientific proof.
  • You may eat your cookies (only after lab is done, you will not receive more than your share!
  • Clean up!!

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