Chapter%201:%20Scientists

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Chapter 1 Scientists Tools
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Introductory Activity

• Think about the following questions
• What does doing science mean to you?
• Who does science?
• What do scientists do?
• What do you think of when you hear about science
  or scientists?
• What comes to mind when you hear about
  chemistry or chemists?
• Do you think science plays an important role in
  your life? If yes, where do you see science in
  your world? If no, explain why not.
• Share your answers with a partner
• Share your answers as a class. 

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Chemistry is an Experimental Science

• This chapter will introduce the following tools
  that scientists use to do chemistry
• Section 1.1 Scientific Processes
• Section 1.2 Observations Measurements
• Section 1.3 Designing Labs
• Section 1.4 Converting Units
• Section 1.5 Significant digits
• Section 1.6 Scientific Notation

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Chemistry is an Experimental Science
Design your own labs
Common characteristics
Unit conversions
Accurate precise measurements
Careful observations
Significant digit rules
Scientific Notation
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Section 1.1Doing Science
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There is no The Scientific Method

• There is no 1 scientific method with X number
  of steps
• There are common processes that scientists use
• Questioning Observing
• Gathering Data
• Experimentation
• Field Studies
• Long-term observations
• Surveys
• Literature reviews
• more
• Analyzing all the data
• Using evidence logic to draw conclusions
• Communicating findings

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Science is loopy
Science is not a linear processrather it is
loopyand its not just about experimentation
there are many pathwayseven more than are shown
here!
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Two types of Experiments

• This text will predominantly use experimentation
  for data gathering
• Two types of experiments will be used
• To investigate relationships or effect
• How does volume affect pressure?
• How does reaction rate change with temperature?
• To determine a specific value
• What is the value of the gas law constant?
• What is the concentration of that salt solution?

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Variables
Dependent Variable
Independent Variable
Controlled by you
You measure or observe
Example How does reaction rate change with
temperature
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Variables
Dependent Variable
Independent Variable
Controlled by you
You measure or observe
Example How does reaction rate change with
temperature
Temperature
Reaction rate
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Variables
Dependent Variable
Independent Variable
Example What is the concentration of that salt
solution?
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Variables

• Variables are not appropriate in specific value
  experiments

Dependent Variable
Independent Variable
Example What is the concentration of that salt
solution?
Not appropriate
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Constants

• Its important to hold all variables other than
  the independent and dependent constant so that
  you can determine what actually caused the change!

Constants
Example How does reaction rate change with
temperature
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Constants

• Its important to hold all variables other than
  the independent and dependent constant so that
  you can determine what actually caused the change!

Constants
Concentrations of reactants
Example How does reaction rate change with
temperature
And maybe you thought of some others!
Volumes of reactants
Method of determining rate of reaction
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Prediction versus Hypothesis

• They are different!

Hypothesis
Prediction
Just predicts
Attempts to explain why you made that prediction
Example How does surface area affect reaction
rate?
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Prediction versus Hypothesis

• They are different!

Hypothesis
Prediction
Just predicts
Attempts to explain why you made that prediction
Example How does surface area affect reaction
rate?
Reaction rate will increase as surface area
increases
Reaction rate will increase with surface area
because more molecules can have successful
collisions at the same time if more can come in
contact with each other.
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Predictions versus Hypothesis
Hypothesis
Prediction
Example What is the concentration of that salt
solution?
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Predictions versus Hypothesis

• It is not appropriate to make a hypothesis or
  prediction in specific value experiments

Hypothesis
Prediction
Example What is the concentration of that salt
solution?
Not appropriateit would just be a random guess
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Gathering Data

• Multiple trials help ensure that youre results
  werent a one-time fluke!
• Precisegetting consistent data within
  experimental error
• Accurategetting the correct or accepted
  answer consistently

Example Describe each groups data as not
precise, precise or accurate
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Precise Accurate Data
Precise, but not accurate
Correct value
Example Describe each groups data as not
precise, precise or accurate
Precise Accurate
Correct value
Not precise
Correct value
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Can you be accurate without precise?
This group had one value that was almost right
onbut can we say they were accurate?
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Can you be accurate without precise?
This group had one value that was almost right
onbut can we say they were accurate?
Nothey werent consistently correct. It was by
random chance that they had a result close to the
correct answer.
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Within Experimental Error

• Precise is consistent within experimental error.
  
• What does that mean?
• Every measurement has some error in itwe cant
  measure things perfectly. You wont get exactly
  identical results each time.

You have to decide if the variance in your
results is within acceptable experimental error
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Drawing Conclusions

• Scientists take into account all the evidence
  from the data gathering and draw logical
  conclusions
• Conclusions can support or not support earlier
  hypothesis
• Conclusions can lead to new hypothesis, which can
  lead to new investigations
• As evidence builds for conclusions, theories and
  laws can be formed.

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Theory versus Law

• Many people do not understand the difference
  between these two terms

Law
Theory
Describes why something occurs
Describes or predicts what happens (often
mathematical)
Example The relationship between pressure and
volume
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Theory versus Law

• Many people do not understand the difference
  between these two terms

Law
Theory
Describes why something occurs
Describes or predicts what happens (often
mathematical)
Example The relationship between pressure and
volume
Kinetic Molecular Theoryas volume decreases, the
frequency of collisions with the wall will
increase the collisions are the pressure
Boyles Law P1V1 P2V2
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Communicating Results

• Scientists share results with the scientific
  community to
• Validate findings (see if others have similar
  results)
• Add to the pool of knowledge
• Scientists use many ways to do this
• Presentations and posters at conference
• Articles in journals
• Online collaboration discussions
• Collaboration between separate groups working on
  similar problems