Topic 1 Matter and Measurements AP Chemistry. Wolpa/Advanced Placement Chemistry 2 How to be...
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Topic 1 Matter and Measurements AP Chemistry
Topic 1 Matter and Measurements AP Chemistry. Wolpa/Advanced Placement Chemistry 2 How to be Successful in AP Chemistry Memorize strategies not equations!
Wolpa/Advanced Placement 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
Slide 3
Wolpa/Advanced Placement Chemistry 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
Slide 4
Wolpa/Advanced Placement Chemistry 4 Chemistry The study of
matter and the changes it undergoes
Slide 5
Wolpa/Advanced Placement Chemistry 5 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
Slide 6
Wolpa/Advanced Placement Chemistry 6 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.)
Slide 7
Wolpa/Advanced Placement Chemistry 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.
Slide 8
Wolpa/Advanced Placement Chemistry 8 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
Slide 9
Wolpa/Advanced Placement Chemistry 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
Slide 10
Wolpa/Advanced Placement Chemistry 10 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
Slide 11
Wolpa/Advanced Placement Chemistry 11
Slide 12
Wolpa/Advanced Placement Chemistry 12 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
Slide 13
Wolpa/Advanced Placement Chemistry 13 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 its volume Specific gravity is
the ratio of the mass of a substance to the mass of an equal volume
of water
Wolpa/Advanced Placement Chemistry 15 Density Calculation
Equation d=m/V Example: If an object has a mass of 15.0 g and a
volume of 10cm 3 whats the objects density? d = 15.0 g/ 10.0 cm 3 =
1.50 g/cm 3
Slide 16
Wolpa/Advanced Placement Chemistry 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
Slide 17
Wolpa/Advanced Placement Chemistry 17 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 -273.15C This is defined as 0 K (no degree sign) The
Kelvin degree is the same size as the Celsius degree (K = C +
273.15)
Slide 18
Wolpa/Advanced Placement Chemistry 18 Temperature Scale
Comparison
Slide 19
Wolpa/Advanced Placement Chemistry 19 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
Slide 20
Wolpa/Advanced Placement Chemistry 20 A mixture is a
combination of two or more substances in which the substances
retain their distinct identities. 1. Homogenous mixture composition
of the mixture is the same throughout. 2. Heterogeneous mixture
composition is not uniform throughout. ?
Slide 21
Wolpa/Advanced Placement Chemistry 21 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
Slide 22
Wolpa/Advanced Placement Chemistry 22 Heterogeneous Vs.
Homogeneous Mixtures
Slide 23
Wolpa/Advanced Placement Chemistry 23 Physical means can be
used to separate a mixture into its pure components.
Slide 24
Wolpa/Advanced Placement Chemistry 24 Physical means can be
used to separate a mixture into its pure components. (Mechanical
process) magnet filtration distillation
Slide 25
Wolpa/Advanced Placement Chemistry 25 Physical Change: the
composition of the substance remains the same but the state
changes.
Slide 26
Wolpa/Advanced Placement Chemistry 26 Chemical Change: a new
substance is formed.
Slide 27
Wolpa/Advanced Placement Chemistry 27 Physical Properties:
Identifying properties of a substance. Density Solubility Color
Melting/Boiling Point Crystalline Shape Malleability, Ductility,
Conductivity, Luster Etc.
Slide 28
Wolpa/Advanced Placement Chemistry 28 An extensive property of
a material depends upon how much matter is is being considered. An
intensive property of a material does not depend upon how much
matter is is being considered. mass length volume density
malleability color Extensive and Intensive Properties 1.6
Slide 29
Wolpa/Advanced Placement Chemistry 29 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)
Slide 30
Wolpa/Advanced Placement Chemistry 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
Slide 31
Wolpa/Advanced Placement Chemistry 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
Slide 32
Wolpa/Advanced Placement Chemistry 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.
Slide 33
Wolpa/Advanced Placement Chemistry 33 Example: Accuracy and
Precision
Slide 34
Wolpa/Advanced Placement Chemistry 34 Equations for Precision
and Accuracy 1. Precision 2. Accuracy Absolute Error % AE = (True
value-Avg Value) X 100 True Value
Slide 35
Wolpa/Advanced Placement Chemistry 35 Significant Figures Any
digit that is not zero is significant 1.234 kg 4 significant
figures Zeros between nonzero digits are significant 6006 m 4
significant figures Zeros to the left of the first nonzero digit
are not significant 0.08 L 1 significant figure One or more final
zeros to the right of the decimal point are significant 2.00 mg 3
significant figures 0.00420 g 3 significant figures 10.006000 8 sig
figs AP Chemistry Exam Hint: You must be within 1 sig fig it does
not need to be perfect, but sig figs DO count!
Slide 36
Wolpa/Advanced Placement Chemistry 36 Counting Significant
Figures Atlantic / Pacific Method a. Absent Decimal- Start on
atlantic side of number & cross out all zeroes until 1 st
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 1 st nonzero digit Is reached,
remaining digits are significant
Wolpa/Advanced Placement Chemistry 38 How many significant
figures are in each of the following measurements? 24 mL2
significant figures 3001 g 4 significant figures 0.0320 m 3 3
significant figures 6.400 x 10 4 molecules 4 significant figures
560 kg2 significant figures
Slide 39
Wolpa/Advanced Placement Chemistry 39 Significant Figures
Addition or Subtraction The answer cannot be more accurate than any
of the original numbers. 89.332 1.1+ 90.432 round off to 90.4 one
significant figure after decimal point 3.70 -2.9133 0.7867 two
significant figures after decimal point round off to 0.79 370
-291.33 78.67 Number is rounded to tens place round off to 80
Slide 40
Wolpa/Advanced Placement Chemistry 40 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 3.6666 = 16.536366= 16.5 3 sig
figsround to 3 sig figs 6.8 112.04 = 0.0606926 2 sig figsround to 2
sig figs = 0.061
Slide 41
Wolpa/Advanced Placement Chemistry 41 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? 6.64 + 6.68
+ 6.70 3 = 6.67333 = 6.67 Because 3 is an exact number = 7
Slide 42
Wolpa/Advanced Placement Chemistry 42 Scientific notation
format
Slide 43
Wolpa/Advanced Placement Chemistry 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
Slide 44
Wolpa/Advanced Placement Chemistry 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
Slide 45
Wolpa/Advanced Placement Chemistry 45 SI Units
MeasurementUnitSymbol MassKilogramkg LengthMeterM TimeSeconds
TemperatureKelvinK QuantityMolemol EnergyJouleJ
PressurePascalPa
Wolpa/Advanced Placement Chemistry 47. 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.
Slide 48
Wolpa/Advanced Placement Chemistry 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 - m 3 m 3 -
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
Slide 49
Wolpa/Advanced Placement Chemistry 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
Slide 50
Wolpa/Advanced Placement Chemistry 50 The speed of sound in air
is about 343 m/s. What is this speed in miles per hour? 1 mi = 1609
m1 min = 60 s1 hour = 60 min 343 m s x 1 mi 1609 m 60 s 1 min x 60
min 1 hour x = 767 mi hour meters to miles seconds to hours