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Introduction: Matter and Measurement

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Title: Introduction: Matter and Measurement


1
Introduction Matter and Measurement
Chapter 1
2
The Study of Chemistry
What is chemistry?
  • Chemistry is the study of the properties and
    behavior of matter.
  • Matter anything that occupies space and has
    mass.

3
Classification of Matter
  • States of Matter





4
Classification of Matter
  • States of Matter


Gas
Liquid
Solid
5
Classification of Matter
  • States of Matter

Shape Volume
Gas
Liquid
Solid
6
Classification of Matter
States of Matter
Shape Volume
Gas indefinite
Liquid
Solid
7
Classification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid
Solid
8
Classification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite
Solid
9
Classification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite definite
Solid
10
Classification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite definite
Solid definite
11
Classification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite definite
Solid definite definite
12
Classification of Matter
  • The basic difference between these states is the
    distance between the bodies.
  • Gas bodies are far apart and in rapid motion.
  • Liquid bodies closer together, but still able
    to move past each other.
  • Solid bodies are closer still and are now held
    in place in a definite arrangement.

13
Classification of Matter
14
Classification of Matter
Pure Substances and Mixtures
  • Mixture combination of two or more substances
    in which each substance retains its own chemical
    identity.
  • Homogeneous mixture composition of this mixture
    is consistent throughout.
  • Heterogeneous mixture composition of this
    mixture varies throughout the mixture.

15
Classification of Matter
Pure Substances and Mixtures
  • It is also possible for a homogeneous substance
    to be composed of a single substance pure
    substance.
  • Element A substance that can not be separated
    into simpler substances by chemical means.
  • Compound A substance composed of two or more
    elements united chemically in definite
    proportions.

16
Classification of Matter
Pure Substances and Mixtures
  • The smallest unit of an element is an atom.
  • Atom the smallest unit of an element that
    retains a substances chemical activity.

17
Classification of Matter
Separation of Mixtures
  • Mixtures can be separated by physical means.
  • Filtration.
  • Chromatography.
  • Distillation.

18
Classification of Matter
Separation of Mixtures
19
Classification of Matter
Elements
  • There are 114 elements known.
  • Each element is given a unique chemical symbol
    (one or two letters).
  • Carbon C, nitrogen N, titanium Ti.
  • Notice that the two letter symbols are always
    capital letter then lower case letter because
  • CO carbon and oxygen.
  • Co element cobalt.

20
Classification of Matter
Compounds
  • Formed by combining elements.
  • The proportions of elements in compounds are the
    same irrespective of how the compound was formed.
  • Law of Constant Composition (or Law of Definite
    Proportions)
  • The composition of a pure compound is always the
    same, regardless of its source.

21
Properties of Matter
Physical and Chemical Changes
  • Physical Property (Change) A property that can
    be measured without changing the identity of the
    substance.
  • Example melting point, boiling point, color,
    odor, density
  • Physical changes do not result in a change of
    composition.

22
Properties of Matter
Physical and Chemical Changes
  • Intensive properties independent of sample
    size.
  • Extensive properties - depends on the quantity
    of the sample.

23
Properties of Matter
Physical and Chemical Changes
  • Chemical change (chemical reaction) the
    transformation of a substance into a chemically
    different substance.
  • When pure hydrogen and pure oxygen react
    completely, they form pure water.

24
Scientific Method
25
Scientific Method
Hypothesis tentative explanation based on a
limited number of observations. Scientific law
A concise verbal or mathematical equation that
summarizes a broad variety of observations and
experiences. Theory an explanation of the
general principles of certain phenomena with
considerable evidence or facts to support it.
26
Units of Measurement
SI Units
  • There are two types of units
  • fundamental (or base) units
  • derived units.
  • There are 7 base units in the SI system.
  • Derived units are obtained from the 7 base SI
    units.

27
Units of Measurement
SI Units
  • There are two types of units
  • fundamental (or base) units
  • derived units.
  • There are 7 base units in the SI system.
  • Derived units are obtained from the 7 base SI
    units.
  • Example

28
Units of Measurement
SI Units
29
Units of Measurement
SI Units
30
Units of Measurement
Mass
  • Mass is the measure of the amount of material in
    an object.
  • This is not the same as weight which is dependant
    on gravity.

31
Units of Measurement
Temperature
32
Units of Measurement
Temperature
Kelvin Scale Used in science. Same temperature
increment as Celsius scale. Lowest temperature
possible (absolute zero) is zero Kelvin.
Absolute zero 0 K -273.15oC. Celsius
Scale Also used in science. Water freezes at 0oC
and boils at 100oC. To convert K oC
273.15. Fahrenheit Scale Not generally used in
science. Water freezes at 32oF and boils at
212oF.
33
Units of Measurement
Temperature
Converting between Celsius and Fahrenheit
34
Units of Measurement
Volume
  • The units for volume are given by (units of
    length)3.
  • i.e., SI unit for volume is 1 m3.
  • A more common volume unit is the liter (L)
  • 1 L 1 dm3 1000 cm3 1000 mL.
  • We usually use 1 mL 1 cm3.

35
Units of Measurement
Density
Density mass per unit volume of an object.
36
Uncertainty in Measurement
  • All scientific measures are subject to error.
  • These errors are reflected in the number of
    figures reported for the measurement.
  • These errors are also reflected in the
    observation that two successive measures of the
    same quantity are different.

37
Uncertainty in Measurement
Precision and Accuracy
  • Measurements that are close to the correct
    value are accurate.
  • Measurements which are close to each other are
    precise.
  • Measurements can be
  • accurate and precise
  • precise but inaccurate
  • neither accurate nor precise

38
Uncertainty in Measurement
Precision and Accuracy
39
Uncertainty in Measurement
Significant Figures
  • The number of digits reported in a measurement
    reflect the accuracy of the measurement and the
    precision of the measuring device.
  • All the figures known with certainty plus one
    extra figure are called significant figures.
  • In any calculation, the results are reported to
    the fewest significant figures (for
    multiplication and division) or fewest decimal
    places (addition and subtraction).

40
Uncertainty in Measurement
Significant Figures
  • Non-zero numbers are always significant.
  • Zeros between non-zero numbers are always
    significant.
  • Zeros before the first non-zero digit are not
    significant. Zeros at the end of the number after
    a decimal place are significant.
  • Zeros at the end of a number before a decimal
    place are ambiguous. For this course we will
    consider these to be significant.
  • Example so for this class, the number 10,300
    has 5 significant figures.

41
Uncertainty in Measurement
Significant Figures
  • Multiplication / Division
  • The result must have the same number of
    significant figures as the least accurately
    determined data
  • Example
  • 12.512 (5 sig. fig.)
  • 5.1 (2 sig. fig.)
  • 12.512 x 5.1 64
  • Answer has only 2 significant figures

42
Uncertainty in Measurement
Significant Figures
  • Addition / Subtraction.
  • The result must have the same number of digits to
    the right of the decimal point as the least
    accurately determined data.
  • Example
  • 15.152 (5 sig. fig., 3 digits to the right),
  • 1.76 (3 sig. fig., 2 digits to the right),
  • 7.1 (2 sig. fig., 1 digit to the right).
  • 15.152 1.76 7.1 24.0
  • 24.0 (3 sig. fig., but only 1 digit to the right
    of the decimal point)

43
Uncertainty in Measurement
Rounding rules
  • If the leftmost digit to be removed is less than
    5, the preceding number is left unchanged. Round
    down.
  • If the leftmost digit to be removed is 5 or
    greater, the preceding number is increased by
    1. Round up.

44
Dimensional Analysis
  • In dimensional analysis always ask three
    questions
  • What data are we given?
  • What quantity do we need?
  • What conversion factors are available to take us
    from what we are given to what we need?

45
Dimensional Analysis
  • Method of calculation using a conversion factor.

46
Dimensional Analysis
Example we want to convert the distance 8 in.
to feet. (12in 1 ft)
47
Dimensional Analysis
Example we want to convert the distance 8 in.
to feet. (12in 1 ft)
48
Dimensional Analysis
Problem Convert the quantity from 2.3 x 10-8 cm
to nanometers (nm)
49
Dimensional Analysis
Problem Convert the quantity from 2.3 x 10-8 cm
to nanometers (nm) First we will need to
determine the conversion factors Centimeter (cm)
? Meter (m) Meter (m) ? Nanometer (nm)
50
Dimensional Analysis
Problem Convert the quantity from 2.3 x 10-8 cm
to nanometers (nm) First we will need to
determine the conversion factors Centimeter (cm)
? Meter (m) Meter (m) ? Nanometer (nm) Or 1 cm
0.01 m 1 x 10-9 m 1 nm
51
Dimensional Analysis
Problem Convert the quantity from 2.3 x 10-8 cm
to nanometers (nm) 1 cm 0.01 m 1 x 10-9 m 1
nm Now, we need to setup the equation where the
cm cancels and nm is left.
52
Dimensional Analysis
Problem Convert the quantity from 2.3 x 10-8 cm
to nanometers (nm) 1 cm 0.01 m 1 x 10-9 m 1
nm Now, fill-in the value that corresponds with
the unit and solve the equation.
53
Dimensional Analysis
Problem Convert the quantity from 2.3 x 10-8 cm
to nanometers (nm)
54
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2)
55
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2) First we will need to
determine the conversion factors Mile (mi) ?
kilometer (km) kilometer (km) ? meter (m)
56
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2) First we will need to
determine the conversion factors Mile (mi) ?
kilometer (km) kilometer (km) ? meter (km) Or 1
mile 1.6093km 1000m 1 km
57
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2) Now, we need to setup the
equation where the mi cancels and m is left. 1
mile 1.6093km 1000m 1 km
58
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2) Now, we need to setup the
equation where the mi cancels and m is left. 1
mile 1.6093km 1000m 1 km Notice, that the
units do not cancel, each conversion factor must
be squared.
59
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2)
60
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2)
61
Dimensional Analysis
Problem Convert the quantity from 31,820 mi2 to
square meters (m2)
62
Dimensional Analysis
Problem Convert the quantity from 14 m/s to miles
per hour (mi/hr).
63
Dimensional Analysis
Problem Convert the quantity from 14 m/s to miles
per hour (mi/hr). Determine the conversion
factors Meter (m) ? Kilometer (km) Kilometer(km)
? Mile(mi) Seconds (s) ? Minutes
(min) Minutes(min) ? Hours (hr)
64
Dimensional Analysis
Problem Convert the quantity from 14 m/s to miles
per hour (mi/hr). Determine the conversion
factors Meter (m) ? Kilometer (km) Kilometer(km)
? Mile(mi) Seconds (s) ? Minutes
(min) Minutes(min) ? Hours (hr) Or 1 mile
1.6093 km 1000m 1 km 60 sec 1 min 60 min 1
hr
65
Dimensional Analysis
Problem Convert the quantity from 14 m/s to miles
per hour (mi/hr). 1 mile 1.6093 km 1000m 1
km 60 sec 1 min 60 min 1 hr
66
Dimensional Analysis
Problem Convert the quantity from 14 m/s to miles
per hour (mi/hr). 1 mile 1.6093 km 1000m 1
km 60 sec 1 min 60 min 1 hr
67
Dimensional Analysis
Problem Convert the quantity from 14 m/s to miles
per hour (mi/hr). 1 mile 1.6093 km 1000m 1
km 60 sec 1 min 60 min 1 hr
68
End of Chapter Problems
1.2, 1.16a, 1.18, 1.20, 1.26, 1.36, 1.38, 1.44,
1.52, 1.63, 1.67
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