1. Introduction to Chemistry
Branches of Chemistry
Scientific Method
Experimental Design

2. Chemistry Joke
Q: Why are chemists great at solving problems? A: They have all the solutions!!!

3. Branches of Chemistry Organic Inorganic Analytical Physical
Associated with CARBON compounds.
Inorganic
Associated with NON-CARBON compounds.
Analytical
Associated with the COMPOSITION of samples
Physical
Associated with the BEHAVIOR/ENERGY of compounds
Biochemical
Associated with the chemistry of LIFE

4. 1.3
The Scientific Method
A logical, systematic approach to the solution of a scientific problem.
Steps in the scientific method include:
Making observations
Formulating hypotheses
Testing hypothesis through experimentation
Developing theories or formulating laws.

5. The Scientific Method 1. Making Observations
1.3
The Scientific Method
1. Making Observations
When you use your senses to obtain information, you make an observation.
2. Formulating Hypotheses
A hypothesis is a proposed explanation for an observation.
Observation is an essential step in the scientific method.

6. 1.3
The Scientific Method
3. Testing Hypotheses through Experimentation
An experiment is a procedure that is used to test a hypothesis.
The experimental design is critical to the reliability of the results.

7. Experimental Design
We should have only one manipulated variable and one dependent variable.
We want to test the effect of the manipulated variable on the dependent variable.
For example:
The effect of surface area on solubility
The effect of temperature on pressure

8. Experimental Design Dependent Variable Relies on the Other Y-axis
We often graph our results.
The manipulated variable will be on the x-axis.
The dependent variable will be on the y-axis.
Dependent Variable
Relies on the Other
Y-axis
DRY
Manipulated Variable
Independent
X-axis
MIX

9. Experimental Design
Our results can show a direct relationship or an indirect/inverse relationship.
DIRECT (X/Y)
INDIRECT (XY)

10. Experimental Design We should be careful to change only one variable.
For example, use the same equipment for each trial.
Conduct each trial under the same conditions.

11. Experimental Design We should have a control.
This is a trial in which the manipulated variable is not changed—used for comparison.
We should average the results of many trials.
To find the mean, add the results of each trial and divide by the total number of trials.
More trials produce better reliability of results.
Results should be reproducible by other scientists.
We should report all results, not just the expected ones.

12. Experimental Design
Chemists often use probeware to measure such things as pH, temperature, or pressure.
The probes connect to a computer and the data is graphed automatically.
Computer simulations are also often used to test theories.

13. The Scientific Method 4. Developing Theories
1.3
The Scientific Method
4. Developing Theories
Once a hypothesis meets the test of repeated experimentation, it may become a theory.
A theory is a loooong explanation for WHY something happens.
A theory may need to be changed at some point in the future to explain new observations or experimental results.

14. The Scientific Method 4. Formulating Scientific Laws
1.3
4. Formulating Scientific Laws
A scientific law is a short mathematical statement of WHAT happens.
A scientific law doesn’t try to explain the relationship it describes. That explanation requires a theory.

15. Steps in the Scientific Method
The steps in the scientific method do not have to occur in the order shown. Comparing and Contrasting How are a hypothesis and a theory similar? How are they different?

16. Chemistry Joke
Q: What substance has the formula HIJKLMNO?
A: Water (H to O)!!!