1. ch01_Fundamental Concepts and Units of Measurement 2019.ppt

1
Chapter 1:Fundamental Concepts
and Units of Measurement
Brady & Senese 5th Ed

2
Index
1.1. Chemistry is important for anyone studying the sciences
1.2. The scientific method helps us build models of nature
1.3 Matter is composed of elements, compounds, and
mixtures
1.4. Properties of matter can be classified in different ways
1.5 Measurements are essential to describe properties
1.6. Measurements always contain some uncertainty
1.7. Units can be converted using the factor-label method
1.8. Density is a useful intensive property

1.1. Chemistry is important for anyone studying the sciences 3
Chemistry and the Sciences
• Chemistry- the study of the composition of matter
and its transformations
• Matter- anything that takes up space and has mass
• Chemical reaction- change that results from the
interaction of matter.

1.2. The scientific method helps us build models of nature 4
Scientific Method : Getting Started
Observe a Phenomenon-accurately
describe something we see, taste, feel,
smell or hear
Pose A Question
To Explain The Phenomenon
Form a Hypothesis-a
tentative explanation of
the phenomenon

Scientific Method: Testing the Hypothesis
Experiment to Prove or Disprove
Hypothesis
If experiment proves
hypothesis,
form theory (theoretical model)
If experiment disproves
hypothesis,
Pose new question or hypothesis
Continue experimentation.
If results form pattern, considered
a law

Scientific Method Case Study:
The Process of Growth
• A child sees that a seed, when planted in soil,
watered, and exposed to sunlight, grows to form a
flower. He concludes that all living things require
sunlight, water, and burial in soil to grow.
• Build a case for rebuttal using the scientific
method.

Your Turn!
Which of the following is not a hypothesis
for the observed plant growth?
A. soil is necessary to all growth
B. light is essential to growth of the seed
C. water is required to allow growth
D. plants grow to a greater height if they
receive fertilizer
E. none of the above

Your Turn!
A chicken egg is buried, left in the sun, and watered.
A second egg is left above the soil, watered and left
in the sun. Would this prove that soil is necessary to
growth?
A. Yes
B. No

The Scientific Method- Evaluating The Data
A theory is an explanation (based on well-tested,
internally consistent experimental results) about
why the phenomenon may occur
 it should explain currently available data
 It should be as simple as possible
 It should clearly show underlying
connections
 It should accurately predict future behaviors

The Scientific Method is Cyclical

Atomic Theory Helps Us Visualize Matter
• Air inflates a balloon
 air must be composed of matter
 the matter is colliding with the walls
of the container.
• A leaf floats on water’s surface
 water is composed of particles that
occupy space
• A leaf falls through air, but rests
on water’s surface
 particles are closer in liquid than in
gases

Models Helps Us Visualize Matter

1.3. Matter is Composed of Elements, Compounds, and Mixtures 13
Changes in Matter
• Chemical change- a process that results in
the formation of a new substance
• Evidence? Formation of a new solid, new
liquid, new gas, temperature change, or an
unexpected color change
• Physical change- a process that results in
no new substance, but that may change the
state of those present, or the proportions

Learning Check: Chemical Or Physical Change?
Chemical Physical
Magnesium burns when heated
in a flame
Magnesium metal tarnishes in
air
Magnesium metal melts at
922K
Grape Kool-aid lightens when
water is added

Your Turn!
Which of the following is not a chemical change?
A. a match burns in air
B. ice melts in air
C. an aluminum door whitens in air
D. all of these
E. none of these

• Matter is either a pure substance or a mixture
• Mixtures may be separated using physical methods
such as chromatography, filtration, sieving
Matter Can Be Classified By Its Properties:

What Is An Element?
• Elements - substances that cannot be
decomposed into simpler substances
• shown on the periodic table as symbols:
“K” for potassium and “Na” for sodium
• made of identical atoms, either singly or in
groups

Weird Science
• Eleven symbols bear no resemblance to their English
names - their names are derived from other languages
• Some of these are used in naming, and these are
highlighted
Sb antimony stibium K potassium kalium
Cu copper cuprum Sn tin stannum
Au Gold aurum Na sodium natrium
Ag silver argentum W tungsten wolfram
Fe iron ferrum Hg mercury hydragyrum
Pb lead plumbum

What Is A Compound?
• Compounds - formed from two or more
atoms of different elements combined in a
fixed proportion
• Have different characteristics than the
elements that compose them
• Can be broken down into elements by
some chemical changes

Mixtures
• mixtures consist of varying
amounts of two or more
elements or compounds
• Homogeneous mixtures or
“solutions”- have the same
properties throughout the
sample
 Brass, tap water
• Heterogeneous mixtures-
consist of two or more phases
 Salad dressing, Coca-Cola ™

Learning Check: Classification
Sand Ice
(H2O)
Flour Table Salt
(NaCl)
Pure
Element
Compound
Molecule
Heterogeneous Mix
Homogeneous Mix

Your Turn!
• brass is pure
• natural peanut butter made only by
crushing peanuts is pure
• because blood cells can be distinguished
from plasma under a microscope, blood
is a heterogeneous mixture:
• True
• False
• True
• False
• True
• False

1.4. Properties of matter can be classified in different ways 23
Classification Of Matter By State
Classification by state is based on packing, motion,
and shape
 Solids have fixed shape and volume
 Liquids have fixed volume, but take the container shape
 Gases have to expand to fill the shape and volume of
the container

Properties Of Matter
• Chemical properties describe the behavior
of the matter that leads to the formation of a
new substance: the "reactivity" of the
substance
• Physical properties can be observed about
the matter alone, without changing the
composition

Learning Check: Chemical or Physical
Property?
Chemical Physical
Magnesium metal is grey
Magnesium metal tarnishes in air
Magnesium metal melts at 922K
Magnesium reacts violently with
hydrochloric acid

Your Turn!
Which of the following is a chemical
property?
A. water is colorless
B. water reacts violently with solid Na metal
C. water dissolves table salt
D. all of these
E. none of these

Intensive And Extensive Properties
• Intensive properties are independent of
sample size
 Examples: color, texture and temperature
• Extensive properties depend on sample size
 Examples: volume and mass
• Properties used to identify substances are
always intensive
 Density, color, and texture are often helpful in
identification, but temperature is not

1.5 Measurements are essential to describe properties 28
Measurements are Observations
• Qualitative observations are non-numerical-
- ask “what” or “how” or “why”
• Quantitative observations are numerical--
ask “how much” and are also called
measurements
• This course is general chemistry with
quantitative analysis

Your turn!
Which of the following is a quantitative
observation?
A. the height of the plant
B. the mass of water added
C. the temperature of the day
D. all of the above
E. none of the above

• Always involve a comparison
• Require units
• Involve numbers that are inexact (estimated).
This uncertainty is due to the limitations of
the observer and the instruments used
• In science, all digits in a measurement up to
and including the first estimated digit are
recorded
Measurements:

Measurements and units
• In the U.S., we use the Imperial (USCS)
System
• The scientific community (and most of the
world) uses the metric system
• Variations in the metric system exist, thus a
standard system is used: International
System of Units (SI)
• SI units we will use now:
 Length (m) Mass (kg) Time (s)
Temperature (K)

Measurement Formula SI Units
Area length × width m2
Volume length × width × height m3
Velocity distance/time m/s
Acceleration velocity/time m/s2
Density mass/volume kg/m3
Derived units
involve a combination of base units, including:

Decimal multipliers
Prefix (Symbol) = Numerical Equivalent
• Giga ( G ) = 109
• Mega- ( M ) = 106
• kilo- ( k ) = 103
• centi- ( c ) = 10-2
• milli- ( m ) = 10-3
• micro- ( μ) = 10-6
• nano- ( n ) = 10-9
• pico ( p ) = 10-12

Learning Check: Complete The Missing
Information
kg
10-12 g
nm
106 g
cL
109 Hz
10-9 m
10-2 L
pg
Mg
GHz
103 g

Your Turn!
Identify the correct conversion:
A. Gm=109 m
B. 109 Gm = m
C. Gm = 10-9 m
D. none are correct

You May Encounter Non-SI Metric Units:
measurement name symbol Value
length angstrom Å 10-10m
mass amu
metric ton
u
t
1.66054×10-27 kg
103 kg
time minute
hour
min
h
60 s
3600 s
volume liter L 1000 cm3

Mass- Matter Content
USCS: oz (avdp.), lb, T
Metric: g
SI: kg

Length
USCS: in, ft, yd, mi
Metric: L, cm3
SI: m

Volume-bulk
• measured directly, using
equipment for
volumetric measure
• calculated using
dimensional (length)
information and
appropriate formulas.
1 cm3= 1mL
• USCS: fl. oz., pt., qt.,
gal
• Metric: L, cm3
• SI: m3

Your Turn!
Which of the following is not a USCS unit?
A. ft.
B. m
C. gal.
D. T.

Your Turn!
Which of the following is not a volume unit?
A. mL
B. qt
C. in3
D. cm

Temperature
• USCS: °F
• Metric: °C
• SI: K

Temperature Conversions
  







C
1
K
1
C
15
.
273
C
K 

t
T
F
32
C
5
F
9
C
F










 t
t

Complete The Following:
• 13.5°C=? °F
• 27.50 °F =? °C
• -34.5 °F =?K
F
F
C
C
F
F
t





3
.
56
32
3
.
24
32
5
.
13
5
9












C
C
t
F
C
F
C
t
F
C
F
F
t
C
t
C
F
F
F
t
F
C
t
C
F
F
t

















50
.
2
9
5
1
32
50
.
27
9
5
1
32
5
9
32
32
5
9















 













 


















K
C
t
K
T
C
C
t
F
C
F
C
t
F
C
F
F
t
2
.
236
15
.
273
44
9
.
36
9
5
1
32
5
.
34
9
5
1
32


















 














 











Your Turn!
Which of the following is the lowest temperature?
A. 300. K
B. 16 ºC
C. 55 ºF
D. they are the same

1.6. Measurements always contain some uncertainty 46
• Because each measurement involves an estimate,
measurements always have error.
• Record all measured numbers, including the first
estimated digit
• These digits are called significant digits or
significant figures
• Exact numbers have infinite significant digits
Measurement Error

Significant Digits In A Measurement Are
Limited By Instrument Precision
• Using the first thermometer, the
temperature is 21.3 ºC (3
significant digits)
• Using the more precise (second)
thermometer, the temperature is
21.32 ºC (4 significant digits)

• Errors-inherent error due to the equipment or
procedure
 Changing volume due to thermal expansion or contraction
(temperature changes)
 Improperly calibrated equipment
 procedural design allows variable measurements
• Mistakes-blunders that you know that you have made.
Do not use these data
 Spillage
 Incomplete procedures
 Reading scales incorrectly
 Using the measuring device incorrectly
Errors Arise From A Number Of Sources
Including:

Reducing Error:
• Errors can often be detected by making repeated
measurements
• Error can be reduced by calibrating equipment
• The average or mean reduces data variations: it
helps find a central value

• An accurate measurement is close to the true or
correct value, a “hole-in-one”
• A precise measurement is close to the average of a
series of repeated measurements
• When calibrated instruments are used properly, the
greater the number of significant figures, the greater
is the degree of precision for a given measurement
Accuracy vs. Precision

• Non-zero digits are significant
• Zeros between significant digits are significant
• Zeros to the right of non-zero digits in a number
that contains a decimal point are significant
(Trailing with a decimal point)
• Zeros to the left of the first nonzero digit are never
counted as significant (Leading)
• Zeros at the end of a number without a decimal
point are assumed not to be significant (Trailing
without a decimal place)
Rules For Significant Figures (Sig Figs)

Learning Check: How Many Significant
Figures Are There In The Following?
2.33 3
500.0 4
1000 1
.0500 3

Your Turn!
How many sig. figs. are there in the number 010.010?
A. 2
B. 3
C. 4
D. 5
E. none of these

Rules for combining measurements depend on the
type of operation performed:
• Multiplication and division
 The number of sig. figs in the answer should not be
greater than the number of sig. figs in the factor with
the fewest sig. figs
figs.)
sig.
(2
13
figs.)
sig.
(2
figs.)
sig.
(4
figs.)
sig.
(3
0.64
2.751
3.14




Measurements Limit The Precision Of
Calculated Results

Your Turn!
How many sig. figs. result from the following:
12.33 x 0.00002?
A. 2
B. 3
C. 4
D. 5
E. none of these
Only 1!

The answer should have the same number of decimal places as
the quantity with the fewest number of decimal places (least
precise)
3.247 ← 3 decimal places
41.36 ← 2 decimal places
+125.2 ← 1 decimal place
169.8 ← answer rounded to 1 decimal place
Addition and Subtraction

Your Turn!
How many sig. figs. result from the following:
10.33-0.0344?
A. 2
B. 3
C. 4
D. 5
E. none of these

Exact Numbers
• Numbers that come from definitions are exact and have
no uncertainty
• They can be assumed to contain an infinite number of
significant figures

Your Turn!
How many sig. figs. result from the following?
A. 2
B. 3
C. 4
D. 5
E. none of these
2.2
12.2
-
10.88)
x
(10.0

1.7 Units can be converted using the factor-label method 60
Unit Conversions
• Suppose we wish to convert 25 miles to km.
Further, we know that there are .6215 miles in a
km.
• We can assemble a ratio and solve this problem.
easy enough because we have a direct conversion
between the units
Often, we must piece together multiple steps and this
approach is impractical
1km
miles
0.6215
km
?
miles
25


Definitions of One
• Remember that 3 teaspoons (tsp) = 1 tablespoon
(Tbsp)
• Using the logic that a number divided by its
equivalent = 1, then it follows that:
• Clearly 3/1 is not 1, but the units make the
statement true.
• Thus we could multiply any number by either of
these fractions (1) and the number has the same
value.
1
3tsp
1Tbsp
and
1
1Tbsp
3tsp



Learning Check
Write two fractions from the following conversion factors
• 4 qt = 1 gal
• 8 fl oz=1 c
• 16 oz. = 1 lb
4 qt/ 1gal 1 gal/4 qt
8 fl oz / 1c and 1c/ 8 fl oz
16 oz./1 lb and 1 lb/16 oz.

Using Conversion Fractions
• Since we can multiply by “1” and the value remains
unchanged, we can multiply by these conversion
fractions to change the units of a measurement.
• For example, 12 in = 1 ft so the conversion of 3.5 ft
to in. can be done using one of these two conversion
fractions
1
5
.
3 ft
1
12in
1ft
and
1
1ft
12in














in
ft
in
42
1
12










Your Turn!
Given that 2.205 lb=1 kg, which of the following is an
appropriate conversion factor?
kg
1
lb
1
kg
2.205
lb
2.205
kg
1
lb
2.205
kg
2.205
lb
1 None of
these
E.
D.
C.
B.
A.

USCS Unit Conversions
Mass Volume Distance
16 oz. (avdp.) = 1 lb.
2000 lb. = 1 T.
3 tsp. = 1 Tbsp.
16 Tbsp. = 1 c.
2 c. = 1 pt.
2 pt. = 1 qt.
4 qt. = 1 gal.
8 fl. oz. = 1 c.
12 in. = 1 ft.
3 ft. = 1 yd.
1760 yd. = 1 mi.

USCS to Metric Metric to USCS
Length 1 in. = 2.54 cm 1 m = 39.37 in
1 yd = 0.9144 m 1 km = 0.6215 mi
1 mi = 1.609 km
Mass 1 lb = 453.6 g 1 kg = 2.205 lb
1 oz = 28.35 g
Volume 1 gal = 3.785 L 1 L = 1.0567 qt
1 qt = 946.4 mL
1 oz (fluid) = 29.6 mL
It is also useful to know that 1 mL = 1 cm3=1 cc
USCS And Metric Units Are Related Using “Critical
Links”

Building Conversion Factors in Unit
Conversions
1. Write the number to be converted as a fraction
(with units)
2. Identify the target units
3. Are the starting units in the same system as the
target?
 If not, you will need a critical link.
 USCS→USCS Conversions: Write down the
conversion factors from smallest to largest .
 metric →metric conversions: Write down the
definitions of all prefixed units.

Learning Check:
Write all conversion factors needed to convert
the following:
• 33 in to yd
• 450 c to gal
• 56 y to s
• 25 mph to ft/s
• 12 in.=1 ft
• 3 ft =1 yd
• 2 c.=1 pt.
• 2 pt.=1 qt.
• 4 qt.=1 gal.
• 60 s=1 min
• 60 min=1 h
• 24 h=1 da
• 365.25 da=1 y
• Distance: 3 ft=1 yd; 1760 yd=1 mi
• Time: 60 s=1 min; 60 min=1 h

Learning Check:
Write all conversion factors needed to convert
the following:
• 33 mm to km
• 450 cg to ng
• 56 µs to Ms
• 25 mL to nL
• mm=10-3 m
• km=103 m
• cg=10-2 g
• ng =10-9 g
• μs=10-6 s
• Ms=109 s
• mL=10-3 m
• nL=10-9 L

Learning Check:
Write Down All Conversion Factors Needed To Convert
The Following:
• 3.03 g to T
• 0.545 ft to km
• 25 mph to km/s
• Crit. Link: 453.6 g=1 lb
• US→US: 2000 lb = 1 T
• CL: 2.54 cm=1 in
• US→US: 12 in=1 ft
• m→m: cm=10-2 m; km=103 m
• Distance: CL: 2.54 cm =1 in
• US→US 12 in = 1 ft; 3 ft= 1 yd; 1760 yd = 1 mi;
• m →m: cm = 10-2 m; km= 103 m
Time:
60 s=1 min
60 min= 1 h

Building Conversion factors (cont).
4. Use the form of the conversion factor that allows
the units to cancel--they must be on opposite
levels of the fraction to cancel.
5. Continue adding conversion factors until the
units match the target units.
2nd Check- are all units written on the page two
times? If so, you have enough info to start the
problem.

Learning Check:
Convert the following:
• 3.03 g to tons
• 0.545 ft. to km
• 5.22 y to s
• 25 mph to km/s
• 3.34(10-6) T
• 1.66(10-4) km
• 1.65(108) s
• 1.1(10-2) km/s

Your Turn!
Given that 2.205 lb = 1 kg, what is the mass of 23.3
lb expressed in kg?
A. 51.4 kg
B. 0.0946 kg
C. 10.6 kg
D. none of these

Your Turn!
Given that 2.54 cm = 1 in, how many km are there in
25 ft?
A. 7.6 km
B. 0.10 km
C. 762 km
D. none of these 7.6(10-3) km!

1.8. Density is a useful intensive property 75
Density (d)
• intensive property defined as the ratio of an
object’s mass (m) to volume (v), d = m/v
• characteristic of pure substances at a specified
temperature
• Since most substances expand when heated,
densities decrease when heated.
• units : g/L for gases and g/mL for solids and
liquids.

Density relates a sample mass and volume
• Blood has a density of 1.05 g/cm3
• We can say that 1.05 g of blood is equivalent to
1.00cm3
• Conversion factors can be constructed from this
equivalence, which could be used in the factor-label
method
blood
g
1.05
blood
cm
1.00
or
blood
cm
1.00
blood
g
1.05 3
3

Learning Check:
A crash sounds from the lab- a large vial of mercury
has fallen from a broken shelf. We call the
hazardous materials team to report the spill, about
2.0 quarts of mercury. They ask for the mass- what
is it? (hint: d=13.69g/mL)
g
mL
g
L
mL
qt
L
qt
)
10
(
6
.
2
69
.
13
10
0567
.
1
1
1
0
.
2 4
3



 

78
Your Turn!
A glass bead with a mass of 5.96 g is dropped into a
beaker of water containing 10.2 mL. If the resulting
volume is 12.3 mL, what is the density of the bead?
A. 2.1 mL
B. 5.96 g
C. 2.8 g/mL
D. 0.35 g/mL

1. ch01_Fundamental Concepts and Units of Measurement 2019.ppt

Recommended

Recommended

More Related Content

Similar to 1. ch01_Fundamental Concepts and Units of Measurement 2019.ppt

Similar to 1. ch01_Fundamental Concepts and Units of Measurement 2019.ppt (20)

Recently uploaded

Recently uploaded (20)

1. ch01_Fundamental Concepts and Units of Measurement 2019.ppt