1. Chapter 1: Scientists’ Tools

2. 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

3. Chemistry is an Experimental Science
Although no
one method,
there are
Design your own labs
Are used
when you
Common characteristics
Unit conversions
May require
include
Accurate & precise measurements
When using in
calculations, follow
Careful observations
Significant digit rules
Scientific Notation
May require using

4. Section 1.1—Doing Science

5. 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

6. Science is “loopy”
Observations
Questions
Data gathering (experiment, literature research, field observations, long-term studies, etc.)
Hypothesis
Trend and pattern recognition
Conclusion formation
Communication & Validation
Model Formation
Product or technology formation
Science is not a linear process…rather it is “loopy”…and it’s not just about experimentation
…there are many pathways…even more than are shown here!

7. 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?

8. How does reaction rate change with temperature
Variables
depends on
Independent Variable
Dependent Variable
Controlled by you
You measure or observe
Example:
How does reaction rate change with temperature

9. How does reaction rate change with temperature
Variables
depends on
Independent Variable
Dependent Variable
Controlled by you
You measure or observe
Example:
How does reaction rate change with temperature
Temperature
Reaction rate

10. What is the concentration of that salt solution?
Variables
Independent Variable
Dependent Variable
Example:
What is the concentration of that salt solution?

11. What is the concentration of that salt solution?
Variables
Variables are not appropriate in specific value experiments
Independent Variable
Dependent Variable
Example:
What is the concentration of that salt solution?
Not appropriate

12. How does reaction rate change with temperature
Constants
It’s 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

13. Constants
It’s 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

14. Prediction versus Hypothesis
They are different!
Prediction
Hypothesis
Just predicts
Attempts to explain why you made that prediction
Example:
How does surface area affect reaction rate?

15. Prediction versus Hypothesis
They are different!
Prediction
Hypothesis
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.

16. Predictions versus Hypothesis
Example:
What is the concentration of that salt solution?

17. Predictions versus Hypothesis
It is not appropriate to make a hypothesis or prediction in specific value experiments
Prediction
Hypothesis
Example:
What is the concentration of that salt solution?
Not appropriate—it would just be a random guess

18. Describe each group’s data as not precise, precise or accurate
Gathering Data
Multiple trials help ensure that you’re results weren’t a one-time fluke!
Precise—getting consistent data within experimental error
Accurate—getting the “correct” or “accepted” answer consistently
Example:
Describe each group’s data as not precise, precise or accurate
Correct value

19. Precise & Accurate Data
Precise, but not accurate
Correct value
Example:
Describe each group’s data as not precise, precise or accurate
Precise & Accurate
Correct value
Not precise
Correct value

20. Can you be accurate without precise?
This group had one value that was almost right on…but can we say they were accurate?
Correct value

21. Can you be accurate without precise?
This group had one value that was almost right on…but can we say they were accurate?
Correct value
No…they weren’t consistently correct. It was by random chance that they had a result close to the correct answer.

22. “Within Experimental Error”
Precise is consistent within experimental error.
What does that mean?
Every measurement has some error in it…we can’t measure things perfectly. You won’t get exactly identical results each time.
You have to decide if the variance in your results is within acceptable experimental error
Correct value

23. 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.

24. Theory versus Law
Many people do not understand the difference between these two terms
Cannot ever become
Theory
Law
Describes why something occurs
Describes or predicts what happens (often mathematical)
Example:
The relationship between pressure and volume

25. Theory versus Law
Many people do not understand the difference between these two terms
Cannot ever become
Theory
Law
Describes why something occurs
Describes or predicts what happens (often mathematical)
Example:
The relationship between pressure and volume
Kinetic Molecular Theory—as volume decreases, the frequency of collisions with the wall will increase & the collisions are the “pressure”
Boyle’s Law:
P1V1 = P2V2

26. 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