General Chemistry
Introduction: Definitions and Measurements
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Chemistry: A Definition
Chemistry is the study of matter, its properties,
as well as its transformations and energy
associated with those transformations.
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Structure of Matter
Nobody fully knows what it really is. Here’s as
much as we could surmise:
• Matter is the “stuff” around us
• The “stuff” is made of molecules and atoms
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Composition of Matter
Individual Substances,
or Compounds:
• identical molecules
• well-defined set of
physical and chemical
properties
Mixtures:
• different molecules
and other particles
• physical and other
properties depend on
relative amounts of
substances in them
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Three States of Matter
SOLID
fixed volume
fixed shape
LIQUID
GAS
fixed volume
changing shape
changing volume
changing shape
liquid water
molecules
molecules of a gas
solid salt crystal
NaCl
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Properties: physical and chemical
Examples of physical
properties:
Examples of chemical
properties:
Melting point
Boiling point
Density
Plasticity
Conductivity
Color
Corrosiveness
Flammability
Other types of
reactivity
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Physical properties
extensive: depend on the amount of substance present
intensive: independent of the amount of substance present
Examples of physical properties and parameters:
Mass, volume - extensive
Melting point - intensive
Boiling point - intensive
Density
Plasticity
Conductivity
Color
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Physical properties
extensive: depend on the amount of substance present
intensive: independent of the amount of substance present
Examples of physical properties and parameters:
Mass, volume - extensive
Melting point - intensive
Boiling point - intensive
Density - intensive
Plasticity - intensive
Conductivity - intensive
Color - intensive
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Properties: example
Zinc
physical properties:
Color:
Melting point:
Boiling point:
Density:
Resistivity:
bluish pale grey metallic
419.53 oC [787.15 oF]
907 oC [1665 oF]
7140 kg/m3
5.9.10-8 W m
some chemical properties:
tarnishes in the air very slowly
dissolves in dilute acid
reacts violently with sulfur
(picture above)
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Energy: chemical potential energy
Physics:
Potential Energy
position of an object
Kinetic Energy
motion of an object
Chemistry:
Chemical potential energy:
energy stored in the molecules and is determined
by their structure (example: fossil fuels).
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A little bit about the scientific method
Dawn of humanity: Trial and Error
Modern Science: Observation → Hypothesis
→ Experiment → Theory
(“educated” trial/error)
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Measurements
Year 1960, International System of Units, SI units
SI Fundamental Units of Measurement
Physical Quantity (Dimension)
Unit Name
Abbreviation
Mass
Length
kilogram
meter
kg
m
Time
Temperature
second
kelvin
s
K
Electric Current
Amount of substance
ampere
mole
A
mol
Luminous intensity
candela
cd
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Measurements Useful in Chemistry
Length
SI:
1 meter (m) = 1.094 yard
1 cm = 10-2 m = 0.3937 in
1 inch = 2.54 cm
Volume
SI:
1 m3
1 L (liter) = 10-3 m3 = 1 dm3
1 mL = 1 cm3 = 10-3 L = 10-3 dm3
1 L = 1.057 quart
1 fluid ounce = 29.57 mL
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Volume: Practice Exercise
The volume of an irregularly shaped solid can be
determined by the volume of water it displaces.
Volume (mL) = volume after - volume before =
21.5 mL - 23.0 mL = 1.5 mL (cm3)
Volume (fl. oz.) =
1 fl. oz = 29.57 mL
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Volume: Practice Exercise
The volume of an irregularly shaped solid can be
determined by the volume of water it displaces.
Volume (mL) = volume after - volume before =
21.5 mL - 23.0 mL = 1.5 mL (cm3)
Volume (fl. oz.) =
1 fl. oz = 29.57 mL
1 fl. oz = 1 mL
29.57
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Volume: Practice Exercise
The volume of an irregularly shaped solid can be
determined by the volume of water it displaces.
Volume (mL) = volume after - volume before =
21.5 mL - 23.0 mL = 1.5 mL (cm3)
Volume (fl. oz.) = 1.5 mL × 1 fl oz = 0.05 fl oz
29.57 ml
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Measurements Useful in Chemistry
Mass
SI:
1 kilogram (kg) = 2.205 lb
1 gram (g) = 10-3 kg
Density (d) !
SI:
1 kg/m3 = g/cm3 = g/mL
density =
mass
volume
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Measurements Useful in Chemistry
Temperature
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Measurements Useful in Chemistry
Temperature
T ºC = 5 (T ºF - 32)
9
T ºF = 9 T ºC + 32
5
T ºC = T K + 273
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Temperature: Practice Exercise
The highest daytime temperature recorded on Mars is 27 ºC,
while the average night time temperature is about -107 ºC.
What’s the temperature in Fahrenheit, is it comfortable for
humans?
T ºF = 9 T ºC + 32
5
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Temperature: Practice Exercise
The highest daytime temperature recorded on Mars is 27 ºC,
while the average night time temperature is about -107 ºC.
What’s the temperature in Fahrenheit, is it comfortable for
humans?
Daytime: T ºF = 9 ×27ºC + 32 = 81 ºF
5
T ºF = 9 T ºC + 32
5
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Temperature: Practice Exercise
The highest daytime temperature recorded on Mars is 27 ºC,
while the average night time temperature is about -107 ºC.
What’s the temperature in Fahrenheit, is it comfortable for
humans?
Daytime: T ºF = 9 ×27ºC + 32 = 81 ºF
5
Night time: T ºF = 9 ×(-107ºC) + 32 = -161 ºF
5
T ºF = 9 T ºC + 32
5
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Measurements Useful in Chemistry
Time
SI standard unit: second (s)
1 hour = 60 min
1 min = 60 s
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Significant Figures/Uncertainty in
Measurement
• All devices have limited sensitivity → uncertainty in
measurement
2.84 ± 0.01 g; 82740 ± 5 years
• “we always estimate the rightmost digit”
• significant figures: all figures we record in measurement
2.84 g; 82740 years
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Which Figures Are Significant?
0.0009039 m
9.1 × 10-5 s
400 L
400. L
400.0 L
 all non-zero digits are significant
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Which Figures Are Significant?
0.0009039 m
9.1 × 10-5 s
400 L
400. L
400.0 L
4 sf
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Which Figures Are Significant?
0.0009039 m
4 sf
9.1 × 10-5 s
400 L
400. L
400.0 L
2 sf
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Which Figures Are Significant?
0.0009039 m
4 sf
9.1 × 10-5 s
2 sf
400 L
400. L
400.0 L
1 sf
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Which Figures Are Significant?
0.0009039 m
4 sf
9.1 × 10-5 s
2 sf
400 L
400. L
1 sf
3 sf
400.0 L
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Which Figures Are Significant?
0.0009039 m
4 sf
9.1 × 10-5 s
2 sf
400 L
400. L
400.0 L
1 sf
3 sf
4 sf
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Some Math
1. multiplication and division: the answer has the same
number of sf as the measurement with the fewest sf:
Volume (cm3) = 1.23542 cm × 1.0365 cm × 3 cm = 4 cm3
2. addition and subtraction: the answer has the same
number of decimal places as the measurement with the
fewest number of decimal places.
Volume (mL) = 34.1 ml + 4.943567238956 mL = 39.0 mL
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Chapter 1: Overview
Properties: physical/chemical
States of matter: volume/shape
SI standard units of measurement
Measurements: significant figures/uncertainty
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Chapter 1: Overview
density = mass
volume
T ºC = 5 (T ºF - 32)
9
T ºF = 9 T ºC + 32
5
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Practice Exercises
According to the ancient greek legend, Archimedes discovered the
displacement method of density determination while bathing and
used it to find the composition of the king’s crown. If a crown
weighing 4 lb 13 oz displaces 186 mL of water, is it made of pure
gold (d = 19.2 g/cm3)?
CHM1050_3
Practice Exercises
According to the ancient greek legend, Archimedes discovered the
displacement method of density determination while bathing and
used it to find the composition of the king’s crown. If a crown
weighing 4 lb 13 oz displaces 186 mL of water, is it made of pure
gold (d = 19.2 g/cm3)?
density =
mass
volume
1 kg = 1000 g = 2.205 lb; 1 oz = 28.3 g
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Practice Exercises
According to the ancient greek legend, Archimedes discovered the
displacement method of density determination while bathing and
used it to find the composition of the king’s crown. If a crown
weighing 4 lb 13 oz displaces 186 mL of water, is it made of pure
gold (d = 19.2 g/cm3)?
density =
mass
volume
1 kg = 1000 g = 2.205 lb; 1 oz = 28.3 g
mass = 4 lb × 1000 g + 13 × 28.3 g/oz = 2182 g
2.205 lb
(1814.1 g)
(367.9 g)
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Practice Exercises
According to the ancient greek legend, Archimedes discovered the
displacement method of density determination while bathing and
used it to find the composition of the king’s crown. If a crown
weighing 4 lb 13 oz displaces 186 mL of water, is it made of pure
gold (d = 19.2 g/cm3)?
density =
mass
volume
1 kg = 1000 g = 2.205 lb; 1 oz = 28.3 g
mass = 4 lb × 1000 g + 13 × 28.3 g/oz = 2182 g
2.205 lb
d = 2182 g/186 mL = 11.7 g/mL = 11.7 g/cm3
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Practice Exercises
Copper coins actually contain very little copper. If a coin is
97.3% zinc (d = 7.14 g/cm3) and 2.7% copper (d = 8.95 g/cm3) by
mass, what is its density?
density =
mass
volume
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Practice Exercises
Copper coins actually contain very little copper. If a coin is
97.3% zinc (d = 7.14 g/cm3) and 2.7% copper (d = 8.95 g/cm3) by
mass, what is its density?
density =
mass =
mass (Cu) + mass (Zn)
volume
volume (Cu) + volume (Zn)
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Practice Exercises
Copper coins actually contain very little copper. If a coin is
97.3% zinc (d = 7.14 g/cm3) and 2.7% copper (d = 8.95 g/cm3) by
mass, what is its density?
density =
mass =
mass (Cu) + mass (Zn)
volume
volume (Cu) + volume (Zn)
0.973 g
3
=
0.136
cm
7.14 g/cm3
Volume (Cu) = 0.027 g 3 = 0.003 cm3
8.95 g/cm
Volume (Zn) =
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Practice Exercises
Copper coins actually contain very little copper. If a coin is
97.3% zinc (d = 7.14 g/cm3) and 2.7% copper (d = 8.95 g/cm3) by
mass, what is its density?
density =
mass =
mass (Cu) + mass (Zn)
volume
volume (Cu) + volume (Zn)
0.973 g
3
=
0.136
cm
7.14 g/cm3
Volume (Cu) = 0.027 g 3 = 0.003 cm3
8.95 g/cm
Volume (Zn) =
1.000 g
density = 0.139 cm3 = 7.19 g/cm3
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