Chapter 1 1

Chapter 1 Chemistry: The Study of Change

The majority of this chapter is not tested directly as material in AP Chemistry, but it contains

important background information that crops up in many problems. The emphasis from this

chapter is on knowing the metric system, basic vocabulary, significant figures, and density. Since

the AP exam is used internationally, students only need to know international units and how to

convert between them for the exam. For example, the only temperatures given on the exam are in

Celsius or Kelvin, so students will not be tested on conversions of Fahrenheit to Celsius. The

only pressures used on the test thus far are mmHg (torr) and atmospheres.

Students should understand how to look at the units in a problem as it can frequently help in

formulating the proper set-up for calculating the answer (dimensional analysis). Density and

conversion problems provide an excellent, simple training ground for such use, even though

problems in AP Chemistry will never be presented in nonmetric units. Students also need to be

able to tell if their answer is sensible.

Major Concepts to Know

• Students should understand the differences between mixtures and substances and should be

able to choose proper techniques for separating mixtures and substances. In lab questions, the

student should be able to choose between methods like distillation, filtration, titration,

electrolysis, and evaporation.

• Elements given the element symbols for 1 through 38 and Ag, Cd, I, Xe, Cs, Ba, W, Hg, Pb,

Sn, Rn, Fr, U, Th, Pu, and Am. They should know how to write symbols correctly with a

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capital for the first letter and lower case second letter (e.g., cobalt is Co, not CO). They

should also be able to locate these elements quickly on the periodic table provided on the

exam. The exam table has symbols, not names, for the elements.

• Three states of matter symbols s, l, and g.

• 1 mL = 1 cm3 (see the diagram below).

• Prefixes including mega-, kilo-, milli-, micro-, and nano-. Others are very rarely used.

• Distinction between extrinsic and intrinsic properties. The former depending on the quantity

of material, such as mass and volume, and the latter, such as density and color on the material

itself regardless of the amount present.

• Relationships between different units (e.g., 1 mL = 1 cm3).

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• The relationship between derived properties, such as density, and measured quantities, such

as mass and volume.

• How to distinguish between physical properties and chemical properties as well as physical

changes and chemical changes.

Distinction Between Physical and Chemical Changes

• Types of lab equipment and how to choose the right one for a measurement. For example,

choosing between a 100 mL beaker, 100 mL graduated cylinder, or 100 mL volumetric flask

to make a solution of approximate or accurate concentration.

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• The names of basic measuring devices and what they are used for and not used for, including

a balance—even if your program doesn’t allow for direct personal use of these by your

students.

Vocabulary to Know

• Density

• Matter, substance, mixture (including

homogeneous and heterogeneous), and

element

• Percent error

• Qualitative and quantitative

• Physical properties and change; chemical

properties and change

• Significant figures

Math Skills to Know

• How to use significant figures in addition, subtraction, multiplication, division, and logs.

Although not covered in the chapter, the rules for significant figures with logs are given in

Appendix 4, page A-13. On the AP exam, in the past students could be ±1 of the real number

of digits for full credit. For instance, if the answer required three significant digits, the

student would get credit for two, three, or four digits. This means they cannot write all the

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digits given by the calculator, nor should they round off excessively. They also must know

the advantage of writing the answer in scientific notation. For example, if the answer is 200

mL but there are only two significant digits, the student must write 2.0 102 mL. The exam

is usually careful to distinguish 200 (only one significant figure certain) from 200., where the

decimal point indicates three significant figures.

• How to properly use and write scientific notation. The accepted usage is 10n not E

n.

• Showing work on all problems. The minimum amount of work needed is the formula,

substitution properly set up, and the answer with units clearly expressed.

• How to solve density problems.

Suggested Problems (* also electronic)

• Elements: 13, 14

• Physical and chemical properties and change: 8, 11, 12*, 106

• Substance or mixture: 15, 16*

• Density: 19, 21, 22*, 56, 59

• Conversions: 25, 26, 39*

• Significant figures: 29*, 31*–36*

• Percent error: 77

Suggested Demonstrations or Labs

• Jeffrey A. Paradis, “4.1–4.10 Classification of Matter: Basic Separation Techniques,” Hands

on Chemistry Laboratory Manual (New York, NY: McGraw-Hill, 2006).

• Lee R. Summerlin et al., “Separating Metallic Iron from Cereal,” Chemical Demonstrations:

A Sourcebook for Teachers Volume 2 (An American Chemical Society Publication, May 5,

1988).

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Questions

1. What does chemistry study? Why is it the central science?

2. What is the difference between qualitative and quantitative data?

3. What is matter?

4. Define substance.

5. Define mixtures.

a. Explain the properties of the two types of mixtures:

• homogeneous

• heterogeneous

b. How can mixtures be separated?

6. What are the two types of substances?

a. Define an element.

• What are the rules for writing symbols?

• Name and give the symbol of two elements whose symbols are derived from their

Latin names.

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b. Define a compound.

• How can compounds be separated?

7. Describe the following phases of matter by the closeness of the molecules:

a. solids

b. liquids

c. gases

• Which phase can be compressed?

8. What is a melting point?

9. What is a boiling point?

10. Explain the difference between physical and chemical properties of matter.

a. Name three physical properties.

b. Name three chemical properties.

11. Explain the difference between physical and chemical changes of matter.

a. Give three examples of physical change.

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b. Give three examples of chemical change.

12. What is difference between intensive and extensive properties?

a. Name two extensive properties.

b. Name two intensive properties.

13. What does SI stand for?

14. What are the SI units and symbols for each of the following?

Base Unit Symbol

Length

Mass

Time

Electric current

Temperature

Amount of substance

Luminous intensity

Know all the above units but luminous intensity for general information.

15. What are the sizes and symbols for each prefix?

Prefix Size of unit Symbol

Kilo

Deci

Centi

Milli

Micro

Nano

Pico

16. What is the difference between mass and weight?

a. Which do chemists use?

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17. Derived units are units not directly measured or observed, but calculated. For example, area

is calculated from length x width. Give three other examples.

18. Volume units: 1000 mL = ____L and 1 cm3 = ____mL

19. What is the density formula?

a. Show the rearrangement of the density equation to solve for mass.

b. Show the rearrangement of the density equation to solve for volume.

• What are the units generally used in density for solids and liquids?

• What are the units used in the density of a gas, and why are they different?

20. How do you convert from temperature in degrees Celsius to temperature in Kelvin?

(Note: It is expected you already understand scientific notation. If you do not, please review

this section. It is not the accepted notation to use E for 10. For example, write 6.02 1023

not 6.02E23.)

21. What is the difference between a measured digit and an exact number?

22. Define significant figures (sig. figs.).

a. What are the five rules for counting sig. figs.?

b. What are the rules for adding or subtracting numbers with sig. figs.?

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c. What are the rules for multiplying or dividing with sig. figs.?

23. Define accuracy.

24. Define precision.

a. Can one be accurate but not precise? Explain.

(Note: It is expected you can do dimensional analysis (factor labeling) to determine the

proper units to use in a calculation. If you are not sure, please review this section.