Chapter 11 Matter and Measurement Chapter 1. 2 The Study of Chemistry What is Chemistry? Chemistry...
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Transcript of Chapter 11 Matter and Measurement Chapter 1. 2 The Study of Chemistry What is Chemistry? Chemistry...
Chapter 1 1
Matter and MeasurementMatter and Measurement
Chapter 1Chapter 1
Chapter 1 2
The Study of ChemistryThe Study of Chemistry
What is Chemistry?What is Chemistry?
Chemistry is the study of the properties and behavior of matter.
Matter – anything that occupies space and has mass.
Chapter 1 3
Classification of MatterClassification 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.
Chapter 1 4
Classification of MatterClassification of Matter
Chapter 1 5
Classification of MatterClassification of Matter
Chapter 1 6
Classification of MatterClassification of Matter
Pure Substances and MixturesPure 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.• Solution (Air, gasoline)
– Heterogeneous mixture – composition of this mixture varies throughout the mixture.
Chapter 1 7
Classification of MatterClassification of Matter
Separation of MixturesSeparation of MixturesMixtures can be separated by physical means.
– Filtration.
– Chromatography.
– Distillation.
Chapter 1 8
Classification of MatterClassification of Matter
Separation of MixturesSeparation of Mixtures
Chapter 1 9
Classification of MatterClassification of Matter
Pure Substances and MixturesPure Substances and MixturesIt 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.• Atom – the smallest unit of an element that retains a
substances chemical activity.
Chapter 1 10
Classification of MatterClassification of Matter
ElementsElements• 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
Chapter 1 11
Classification of MatterClassification of Matter
Pure Substances and MixturesPure Substances and MixturesIt is also possible for a homogeneous substance to
be composed of a single substance – pure substance.
• Compound – A substance composed of two or more elements united chemically in definite proportions.
Chapter 1 12
Classification of MatterClassification of Matter
CompoundsCompounds• 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.
Chapter 1 13
Properties of MatterProperties of Matter
Physical and Chemical ChangesPhysical and Chemical ChangesPhysical Property – A property that can be measured
without changing the identity of the substance.
Example: color, odor, density
Chapter 1 14
Properties of MatterProperties of Matter
Physical and Chemical ChangesPhysical and Chemical Changes
Intensive properties – independent of sample size.
Extensive properties - depends on the quantity of the sample (sample size).
Chapter 1 15
Units of MeasurementUnits of Measurement
DensityDensityDensity – mass per unit volume of an object.
volume
massDensity
Chapter 1 16
Properties of MatterProperties of Matter
Physical and Chemical ChangesPhysical and Chemical Changes
Physical change – the change in the physical properties of a substance.
– Physical appearance changes, but the substances identity does not.
Water (ice) Water (liquid)
Chapter 1 17
Properties of MatterProperties of Matter
Physical and Chemical ChangesPhysical 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.
Chapter 1 18
Properties of MatterProperties of Matter
Physical and Chemical ChangesPhysical and Chemical Changes
Chapter 1 19
Units of MeasurementUnits of Measurement
m/ssecondsmeters
time of unitsdistance of units
velocity of Units
SI UnitsSI 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:
Chapter 1 20
SI UnitsSI Units
Units of MeasurementUnits of Measurement
Chapter 1 21
Units of MeasurementUnits of Measurement
SI UnitsSI Units
Chapter 1 22
Units of MeasurementUnits of Measurement
TemperatureTemperature
Chapter 1 23
Units of MeasurementUnits of Measurement
TemperatureTemperatureKelvin 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 ScaleAlso used in science.Water freezes at 0oC and boils at 100oC.To convert: K = oC + 273.15.
Fahrenheit ScaleNot generally used in science.Water freezes at 32oF and boils at 212oF.
Chapter 1 24
Units of MeasurementUnits of Measurement
TemperatureTemperature
Converting between Celsius and Fahrenheit
32-F95
C
32C59
F
Chapter 1 25
Units of MeasurementUnits of Measurement
VolumeVolume• 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.
Chapter 1 26
MassMassMass is the measure of the amount of material in an Mass is the measure of the amount of material in an
object.object.– This is not the same as weight which is dependant on This is not the same as weight which is dependant on
gravity.gravity.
Units of MeasurementUnits of Measurement
Chapter 1 27
• 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.
Uncertainty in MeasurementUncertainty in Measurement
Chapter 1 28
Precision and AccuracyPrecision 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.
Uncertainty in MeasurementUncertainty in Measurement
Chapter 1 29
Precision and AccuracyPrecision and Accuracy
Uncertainty in MeasurementUncertainty in Measurement
Chapter 1 30
Uncertainty in MeasurementUncertainty in Measurement
Significant FiguresSignificant Figures• The number of digits reported in a measurement
reflect the accuracy of the measurement and the precision of the measuring device.
• The last digit to the right in a number is taken to be inexact.
• In any calculation, the results are reported to the fewest significant figures (for multiplication and division) or fewest decimal places (addition and subtraction).
Chapter 1 31
Uncertainty in MeasurementUncertainty in Measurement
Significant FiguresSignificant 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 book, it a decimal point is used the zeros are significant.
– 10,300 has 3 significant figures.
– 10,300. has 5 significant figures.
• Physical constants are “infinitely” significant.
Chapter 1 32
Uncertainty in MeasurementUncertainty in Measurement
Significant FiguresSignificant Figures• Multiplication / DivisionMultiplication / Division
– The result must have the same number of significant figures as The result must have the same number of significant figures as the least accurately determined datathe least accurately determined data
Example: Example:
12.512 (5 sig. fig.) 12.512 (5 sig. fig.)
5.1 (2 sig. fig.)5.1 (2 sig. fig.)
12.512 x 5.1 = 64 12.512 x 5.1 = 64
Answer has only 2 significant figuresAnswer has only 2 significant figures
Chapter 1 33
Uncertainty in MeasurementUncertainty in Measurement
Significant FiguresSignificant Figures• Addition / Subtraction.Addition / Subtraction.
– The result must have the same number of digits to the right of The result must have the same number of digits to the right of the decimal point as the least accurately determined data.the decimal point as the least accurately determined data.
Example:Example:
15.152 (5 sig. fig., 3 digits to the right),15.152 (5 sig. fig., 3 digits to the right),
1.76 (3 sig. fig., 2 digits to the right),1.76 (3 sig. fig., 2 digits to the right),
7.1 (2 sig. fig., 1 digit to the right).7.1 (2 sig. fig., 1 digit to the right).
15.152 + 1.76 + 7.1 = 24.0.15.152 + 1.76 + 7.1 = 24.0.
24.0 (3 sig. fig., but only 1 digit to the right of the decimal point).24.0 (3 sig. fig., but only 1 digit to the right of the decimal point).
Chapter 1 34
Uncertainty in MeasurementUncertainty 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.”
Chapter 1 35
Dimensional AnalysisDimensional 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?
Chapter 1 36
Dimensional AnalysisDimensional Analysis
• Method of calculation using a conversion factor.
inches
footor
foot
inches
footinches
12
11
1
121
112
Chapter 1 37
Dimensional AnalysisDimensional Analysis
Example: We want to convert the distance 8 in. to feet.
(12in = 1 ft)
in
ftin
12
18
Chapter 1 38
Dimensional AnalysisDimensional Analysis
Example: We want to convert the distance 8 in. to feet.
(12in = 1 ft)
ftin
ftin 67.0
12
18
Chapter 1 39
Dimensional AnalysisDimensional Analysis
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
Chapter 1 40
Dimensional AnalysisDimensional Analysis
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.
m
nm
cm
mcm8103.2
Chapter 1 41
Dimensional AnalysisDimensional Analysis
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.
m
nm
cm
mcm
98
101
1
1
01.0103.2
Chapter 1 42
Dimensional AnalysisDimensional Analysis
Convert the quantity from 2.3 x 10-8 cm to nanometers (nm)
nmm
nm
cm
mcm 23.0
101
1
1
01.0103.2
98
Chapter 1 43
Dimensional AnalysisDimensional Analysis
Convert the quantity from 31,820 mi2 cm to square meters (m2)
First we will need to determine the conversion factors
Mile (mi) Meter (m)
Meter (m) kilometer (km)
Or
1 mile = 1.6093km
1000m = 1 km
Chapter 1 44
Dimensional AnalysisDimensional Analysis
Convert the quantity from 31,820 mi2 cm to square meters (m2)
Now, we need to setup the equation where the cm cancels and nm is left.
1 mile = 1.6093km 1000m = 1 km
km
m
mi
kmmi 2820,31
Chapter 1 45
Dimensional AnalysisDimensional Analysis
Convert the quantity from 31,820 mi2 cm to square meters (m2)
Now, we need to setup the equation where the cm cancels and nm is left.
1 mile = 1.6093km 1000m = 1 km
Notice, that the units do not cancel, each conversion factor must be “squared”.
22
2820,31km
m
mi
kmmi
Chapter 1 46
Dimensional AnalysisDimensional Analysis
Convert the quantity from 31,820 mi2 cm to square meters (m2)
22
2
1
1000
1
6093.1820,31
km
m
mi
kmmi
Chapter 1 47
Dimensional AnalysisDimensional Analysis
Convert the quantity from 31,820 mi2 cm to square meters (m2)
2
26
2
22
1
101
1
5898.2820,31
km
m
mi
kmmi
Chapter 1 48
Dimensional AnalysisDimensional Analysis
Convert the quantity from 31,820 mi2 cm to square meters (m2)
2102
26
2
22 102407.8
1
101
1
5898.2820,31 m
km
m
mi
kmmi
Chapter 1 49
Dimensional AnalysisDimensional Analysis
Convert the quantity from 14 m/s cm 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
Chapter 1 50
Dimensional AnalysisDimensional Analysis
Convert the quantity from 14 m/s cm to miles per hour (mi/hr).
1 mile = 1.6093 km 1000m = 1 km
60 sec = 1 min 60 min = 1 hr
hr
min
min
s
km
mi
m
km/14 sm
Chapter 1 51
Dimensional AnalysisDimensional Analysis
Convert the quantity from 14 m/s cm to miles per hour (mi/hr).
1 mile = 1.6093 km 1000m = 1 km
60 sec = 1 min 60 min = 1 hr
hr1
min60
min1
s60
km6093.1
mi1
m1000
km1/14 sm
Chapter 1 52
Dimensional AnalysisDimensional Analysis
Convert the quantity from 14 m/s cm to miles per hour (mi/hr).
1 mile = 1.6093 km 1000m = 1 km
60 sec = 1 min 60 min = 1 hr
hrmi
sm
/31
hr1
min60
min1
s60
km6093.1
mi1
m1000
km1/14
Chapter 1 53
End of Chapter ProblemsEnd of Chapter Problems
4, 10, 14, 20, 26, 34, 42, 60