1. Welcome to Pre-AP Chemistry
Agenda for Class 1
Introduction
Seating Assignments
Distribution of Books and Chapter 1 and 2 Handouts
Discussion of Class Rules
Assignments for Chapter 1
Demonstrations

2. Introduction Syllabus Discussion Grades Assignments/Homework
Opportunity for Questions About Dr. Lutz
Three Interesting Things About You

3. Experimental Design Hypothesis Designing an Experiment
The statement of the hypothesis should include some attempt to explain the cause for what you observe and should include quantities that are measurable (variables). For example:
The amount of fertilizer used will impact how fast and how large plants will grow.
Amount of fertilizer is the independent variable (we choose how much to use).
How fast and how large are dependent variables (depend on how the plants respond to the fertilizer)
Designing an Experiment
A quality design must be able to determine whether (and by how much) changing the independent variable impacts the dependent variable. In addition, the experiment must be repeated several times to show that the results are reproducible. Lastly a quality design must have something to compare to (called a control) in order to show that any changes in the dependent variable came about because of the independent variable and not other outside factors.

4. Example:
Hypothesis: The amount of salt that you can dissolve in water will increase when the temperature of the water is higher than room temperature.
Proposed experimental design:
Step 1: measure the number of grams of salt that dissolve in 1.0 L of water at 22oC (normal room temperature).
Step 2: measure the number of grams of salt that dissolve in 1.0 L of water at 35oC.
Step 3: measure the number of grams of salt that dissolve in 1.0 L of water at 45oC.
Repeat Steps 1-3 several times and use the average number of grams of salt measured.
Problems: A) Identify the independent variable(s)
B) Identify the dependent variable(s)
C) Which step or steps would be identified as the control?
D) What is the purpose of repeating steps 1-3 several times?

5. Laboratory activity: Paper Helicopter
Goals:
Change the design of a paper helicopter so that it will stay in the air longer than the standard paper helicopter.
Perform experiments to determine what effects your design changes had on the flying time of the paper helicopter.
Materials: Paper helicopter sheet,
Scissors
Tape
Watch
Conclusion:
Identify the variables in your experiments (dependent and independent).
Identify the control you used in your experiments.

6. Bonus Problem:
Briefly describe experiments (i.e. write out steps) that could be used to test the hypothesis below. Afterwards, clearly identify the independent variable(s), the dependent variable(s), and the control experiment.
Hypothesis: The time it take for a fixed amount of salt to dissolve in water depends upon the amount of water and the amount of stirring.

8. Chapter 1: Introduction to Chemistry
Objectives: The student will be able to:
identify and analyze two or three ways in which chemistry impacts daily life;
understand and follow safety procedures in the laboratory and in emergencies;
incorporate new vocabulary into discussions;

9. Chemistry:
Chemistry is the study of matter and the changes in energy involved when matter changes forms.
However, heat and light are components of many chemical reactions!

10. What does “weightless” mean?
How is it possible to be weightless?
Can we compare and contrast the terms “mass” and “weight”?
Mass is a measure of the quantity of matter that is present.
Weight is a measure of the force of gravity on a mass.

11. Matter:
Matter is anything that has mass and takes up space (has a volume). Matter is often made up of small pieces called atoms or molecules.
Mass and Weight are not the same thing.
For example, an object that has a mass of 1.0 kg will have a weight of 1.0 kg on the surface of the earth but would only have a weight of 0.17 kg on the moon. However, the mass would be 1.0 kg on both the earth and the moon.

12. On a balance, mass = 1.0 kg On a scale, weight = 1.0 kg
Earth
Moon
A balance works in a different way than a scale.

13. “Atoms” vs. “Molecules”
Atom: smallest particle of matter that can be recognized as a specific element.
Molecule: combination of two or more atoms.

14. Oxygen and Hydrogen Molecules
Ozone would be written as O3

15. A “Chemical Reaction”
A chemical reaction is a process where one or more substances become different substances. In the following example, the compound water is becoming the element oxygen and the element hydrogen. Note that since there are 2 oxygen atoms in the elemental form oxygen and 2 hydrogen atoms in the elemental form of hydrogen, these two elements can also be called compounds or molecules.

16. As an equation: 2 H2 + O2 → 2 H2O + Heat
Chemical Reactions can often be performed in either the forward or reverse direction. The reaction below is in the opposite direction to the previous example. Here, oxygen is reacting with hydrogen to make water.
As an equation: 2 H O2 → 2 H2O Heat

17. A law summarizes what happens.
Law vs. Theory
A law summarizes what happens.
A theory (model) is an attempt to explain why it happens.
A law is so well accepted that no one believes that it could be incorrect.
A theory explains why something happens, but scientists believe that there may be some facts that the theory will not correctly explain.

18. What is unusual about this graph?
Graphing is a common method used to summarize experimental data.
(see the graph below from data in Chapter 1)
What is unusual about this graph?

19. Equation for the line is:
Independent Variable is the one you choose to change (should be plotted on the x axis)
Dependent Variable is the one that changes on its own (should be plotted on the y axis)
Equation for the line is:
What information is being graphed here?
y = 9.75(x)
What is the independent variable?
What does slope mean here?
What is the dependent Variable?

20. Equation for the line is: y = x - 1722
How does the slope of the line compare to the previous one and what does that imply?
y = x

21. Branches of Chemistry: Organic Chemistry
Inorganic Chemistry
Physical Chemistry
Analytical Chemistry
Biochemistry
Study of compounds containing carbon.
Study of compounds that do not
contain carbon.
Study of energy changes associated with chemical and physical changes.
Quantification of the amount of a substance present in a mixture.
Study of chemistry that occurs in living systems.