1. Matter and Measurements AP Chemistry
Topic 1
Matter and Measurements
AP Chemistry

2. How to be Successful in AP Chemistry
Memorize strategies not equations!
Study a lot!
Work ALL the problems.
Self-evaluate after test results.
Make use of Tutorial.
Start a Study Group
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3. Chapter 1: Matter and Measurement
Overview:
The Study of Chemistry
Classifications of Matter
Properties of Matter
Units of Measurement
Uncertainty in Measurement
Dimensional Analysis
Basic Math Concepts
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4. Wolpa/Advanced Placement Chemistry
The study of matter and the changes it undergoes
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5. Wolpa/Advanced Placement Chemistry
Matter
Anything that has mass and occupies space
Characterized by physical and chemical properties
Law of the Conservation of Mass - matter is neither created nor destroyed in chemical reactions
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Element
An element is a pure substance composed of one type of atom.
An atom is the smallest particle of an element that retains the chemical properties of the element.
An element is the most basic form of matter under ordinary circumstances
Simplest chemical substance
Only a few elements are found in their free state (nitrogen, oxygen, gold, etc.)
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7. Elements and the Periodic Table
Each element is represented by a name and a symbol. (Periods/groups - alkali metals, alkaline earth metals, halogens, noble gases)
The first letter is always capitalized the second (and third) are never capitalized.
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8. Wolpa/Advanced Placement Chemistry
Compound
A unique substance composed of two or more elements that are chemically combined (i.e. joined intimately, not just mixed together)
Pure compounds have definite compositions and properties
Require complex chemical procedures to separate into simpler substances (elements)
Compounds include water, table salt, sugar, etc
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9. Properties of Substances
Elements and Compounds are pure substances.
Properties describe the particular characteristics of a substance
Pure substances have definite composition and definite, unchanging properties
Physical properties - can be observed without changing the substance
Chemical properties - require that the substance change into another
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10. Wolpa/Advanced Placement Chemistry
Physical States
The three physical states are solid, liquid and gas
solids - have a definite shape and volume
liquid - have a definite volume but not a definite shape
gas - neither a definite volume or shape
A substance exists in a particular physical state under defined conditions
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Phase Changes
Melting point or freezing point
temperature at which a substance changes from solid to liquid
Boiling point or condensation point
temperature at which a substance changes from liquid to gas
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13. Wolpa/Advanced Placement Chemistry
Density
ratio of the mass of a substance to the volume of that mass
usually measure in g/mL for solids and liquids; g/L for gases
also a conversion factor relating the mass of a substance to it’s volume
Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of water
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What’s happening?
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Density Calculation
Equation
d=m/V
Example:
If an object has a mass of 15.0 g and a volume of 10cm3 what’s the objects density?
d = 15.0 g/ 10.0 cm3 = 1.50 g/cm3
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16. Temperature and its Measurement
Temperature - measure of the intensity of the heat of a substance
Thermometer - device to measure temperature
Kelvin - K - SI unit of temperature
Celsius - °C - commonly used unit
Fahrenheit - °F - only used in USA
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17. Wolpa/Advanced Placement Chemistry
The Kelvin scale
The idea of negative temperatures is a problem for any mathematical treatment of temperature dependent properties.
It was found that a practical minimum temperature did exist (absolute zero) which has a value of °C
This is defined as 0 K (no degree sign)
The Kelvin degree is the same size as the Celsius degree (K = °C )
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18. Temperature Scale Comparison
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Chemical Properties
Chemical properties - involve how a substance changes into another
Sometimes quite difficult to determine
Some examples are burning (as opposed to boiling) and color changes
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A mixture is a combination of two or more substances in which the substances retain their distinct identities.
Homogenous mixture – composition of the mixture is the same throughout.
Heterogeneous mixture – composition is not uniform throughout. ?
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21. Wolpa/Advanced Placement Chemistry
Mixtures
Combinations of two or more substances
Can be separated by exploiting different physical properties (filtration, distillation, crystallization, chromatography)
Have chemical and physical properties that are different from the substances that make them up
The percentages by mass of the components of a mixture can be varied continuously
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22. Heterogeneous Vs. Homogeneous Mixtures
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Physical means can be used to separate a mixture into its pure components.
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Physical means can be used to separate a mixture into its pure components. (Mechanical process)
distillation
magnet
filtration
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Physical Change: the composition of the substance remains the same but the state changes.
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26. Chemical Change: a new substance is formed.
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27. Physical Properties: Identifying properties of a substance.
Density
Solubility
Color
Melting/Boiling Point
Crystalline Shape
Malleability, Ductility, Conductivity, Luster
Etc.
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28. Extensive and Intensive Properties
An extensive property of a material depends upon how much matter is is being considered.
mass
length
volume
An intensive property of a material does not depend upon how much matter is is being considered.
density
malleability
color
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1.6

29. Wolpa/Advanced Placement Chemistry
Solutions
A type of homogeneous mixture
Usually involves a liquid phase, but can be solid-solid, liquid-liquid, solid-liquid, etc.
The pure substances can be in different phases but form a homogeneous mixture (table salt and water, for example)
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30. Measurements and Units
Measurement - determines the quantity, dimensions or extent of something
1.Consist of two parts
a. a numerical quantity (1.23)
b. a specific unit (meters)
Unit - a definite quantity adapted to as a standard of measurement
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31. Features of Measured Quantities
When we measure a number, there are physical constraints to the measurement
Instruments and scientists are not perfect, so the measurement is not perfect (i. e., it has error)
The error in the measurement is related to the accuracy and the precision of the measurement
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32. Accuracy and Precision
Accuracy – how close the measurement is to the “true” value (of course we have to know what the “true” value is)
Precision – is a measure of how closely individual measurements agree with one another.
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33. Example: Accuracy and Precision
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34. Equations for Precision and Accuracy
Absolute Error
% AE = (True value-Avg Value) X 100
True Value
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35. AP Chemistry Exam Hint:
You must be within 1 sig fig – it does not need to be perfect, but sig figs DO count!
Significant Figures
Any digit that is not zero is significant
1.234 kg significant figures
Zeros between nonzero digits are significant
6006 m significant figures
Zeros to the left of the first nonzero digit are not significant
0.08 L significant figure
One or more final zeros to the right of the decimal point are significant
2.00 mg significant figures
g 3 significant figures
sig figs
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36. Counting Significant Figures
Atlantic / Pacific Method
a. Absent Decimal- Start on “atlantic” side of number & cross out all zeroes until 1st nonzero digit is reached, remaining digits are significant
b. Present decimal- start on the “pacific” side of the number & cross out all zeros until the 1st nonzero digit Is reached, remaining digits are significant
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2. Examples:
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38. Wolpa/Advanced Placement Chemistry
How many significant figures are in each of the following measurements?
24 mL
2 significant figures
3001 g
4 significant figures m3
3 significant figures
6.400 x 104 molecules
4 significant figures
560 kg
2 significant figures
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Significant Figures
Addition or Subtraction
The answer cannot be more accurate than any of the original numbers.
89.332
1.1 +
90.432
one significant figure after decimal point
round off to 90.4
3.70
0.7867
two significant figures after decimal point
round off to 0.79
370
Number is rounded to “tens” place
78.67
round off to 80
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40. Wolpa/Advanced Placement Chemistry
Significant Figures
Multiplication or Division
The number of significant figures in the result is set by the original number that has the smallest number of significant figures
4.51 x =
= 16.5
3 sig figs
round to
3 sig figs
6.8 ÷ =
= 0.061
2 sig figs
round to
2 sig figs
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Significant Figures
Exact Numbers
Numbers from definitions or numbers of objects are considered
to have an infinite number of significant figures
The average of three measured lengths; 6.64, 6.68 and 6.70? 3
= = 6.67
= 7
Because 3 is an exact number
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42. Scientific notation format
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43. Scientific notation and significant figures
1. When using scientific notation the base must be written with the correct number of significant digits
2. All zeroes are significant when using scientific notation
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44. Measurement of mass, length and volume
In the United States, we use a fairly awkward system of measurement for most things - the English system Scientists use the metric and SI systems of units for the measurement of physical quantities
This system using standard units based on very precisely known properties of matter and light
Prefixes are used in from of the units to indicate powers of ten
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45. Wolpa/Advanced Placement Chemistry
SI Units
Measurement
Unit
Symbol
Mass
Kilogram kg
Length
Meter M
Time
Second s
Temperature
Kelvin K
Quantity
Mole
mol
Energy
Joule J
Pressure
Pascal Pa
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46. Wolpa/Advanced Placement Chemistry
SI Prefixes
Prefix
Symbol
Power
tera- T
1012
deci- d
10-1
giga- G
109
centi- c
10-2
mega- M
106
milli- m
10-3
kilo- k
103
micro- 
10-6
hecto- h
102
nano- n
10-9
deca- da
101
pico- p
10-12
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47. Wolpa/Advanced Placement Chemistry
. Base Units
Mass - the quantity of matter that a sample contains
Note that weight is a measure of the attraction of gravity for a sample and it varies depending on the distance of the mass to a planet or moon
Scientists often speak imprecisely of the “weight” of an amount of substance. They really mean mass.
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48. Basic SI units/Derived units
Used to generate new Units
Volume - space a given quantity of matter occupies
Volume - expressed in terms of length - m3
m3 - an inconveniently large volume, so we use liter (L; one cubic decimeter)
We often use a mL (1 cubic centimeter) for more manageable amounts of matter
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49. Converting between units
The standard method to convert between two different units is the factor-label or dimensional analysis method
Dimensional analysis converts a measurement in one unit to another by the use of a conversion factor
Conversion factors are developed from relationships between units
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50. Wolpa/Advanced Placement Chemistry
The speed of sound in air is about 343 m/s. What is this speed in miles per hour?
meters to miles
seconds to hours
1 mi = 1609 m
1 min = 60 s
1 hour = 60 min
343 m s x
1 mi
1609 m
60 s
1 min x
60 min
1 hour x
= 767 mi
hour
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