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Introduction: Matter and Introduction: Matter and MeasurementMeasurement
Chapter 1Chapter 1
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The Study of ChemistryThe Study of Chemistry
Chemistry is the study of the properties and behavior of matter.
Matter – anything that occupies space and has mass.
What is chemistry?What is chemistry?
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Classification of MatterClassification of Matter
States of Matter
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Classification of MatterClassification of Matter
States of Matter
Gas
Liquid
Solid
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Classification of MatterClassification of Matter
States of Matter
Shape Volume
Gas
Liquid
Solid
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Classification of MatterClassification of Matter
States of Matter
Shape Volume
Gas indefinite
Liquid
Solid
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Classification of MatterClassification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid
Solid
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Classification of MatterClassification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite
Solid
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Classification of MatterClassification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite definite
Solid
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Classification of MatterClassification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite definite
Solid definite
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Classification of MatterClassification of Matter
States of Matter
Shape Volume
Gas indefinite indefinite
Liquid indefinite definite
Solid definite definite
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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.
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Classification of MatterClassification of Matter
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Classification of MatterClassification of Matter
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.
Pure Substances and Mixtures
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Classification of MatterClassification of Matter
It is also possible for a homogeneous substance to It is also possible for a homogeneous substance to be composed of a single substance – be composed of a single substance – pure pure substance.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.
Pure Substances and Mixtures
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Classification of MatterClassification of Matter
The smallest unit of an element is an atom.
Atom – the smallest unit of an element that retains a substances chemical activity.
Pure Substances and Mixtures
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Classification of MatterClassification of Matter
• Mixtures can be separated by physical means.– Filtration.
– Chromatography.
– Distillation.
Separation of Mixtures
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Classification of MatterClassification of MatterSeparation of Mixtures
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Classification of MatterClassification of Matter
• 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.
Elements
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Classification of MatterClassification of Matter
• 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.
Compounds
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Properties of MatterProperties of Matter
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.
Physical and Chemical Changes
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Properties of MatterProperties of Matter
Intensive properties – independent of sample size.
Extensive properties - depends on the quantity of the sample.
Physical and Chemical Changes
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Properties of MatterProperties of Matter
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.
Physical and Chemical Changes
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Units of MeasurementUnits of Measurement
• 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.
SI Units
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Units of MeasurementUnits of Measurement
m/ssecondsmeters
time of unitsdistance of units
velocity of 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:
SI Units
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SI Units
Units of MeasurementUnits of Measurement
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Units of MeasurementUnits of Measurement
SI Units
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Mass 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 MeasurementMass
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Units of MeasurementUnits of MeasurementTemperature
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Units of MeasurementUnits of Measurement
Kelvin ScaleUsed 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.
Temperature
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Units of MeasurementUnits of Measurement
Converting between Celsius and Fahrenheit
32-F95
C 32C59
F
Temperature
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Units of MeasurementUnits of Measurement
• 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.
Volume
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Units of MeasurementUnits of Measurement
Density – mass per unit volume of an object.
volume
massDensity
Density
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• 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
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• 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
Precision and Accuracy
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Precision and Accuracy
Uncertainty in MeasurementUncertainty in Measurement
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Uncertainty in MeasurementUncertainty in Measurement
• 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).
Significant Figures
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Uncertainty in MeasurementUncertainty in Measurement
• 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.
Significant Figures
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Uncertainty in MeasurementUncertainty in Measurement
• Multiplication / DivisionMultiplication / Division– The result must have the same number of significant The result must have the same number of significant
figures as the least accurately determined datafigures as the 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
Significant Figures
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Uncertainty in MeasurementUncertainty in Measurement
• Addition / Subtraction.Addition / Subtraction.– The result must have the same number of digits to the The result must have the same number of digits to the
right of the decimal point as the least accurately right of the decimal point as the least accurately determined data.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 = 24.015.152 + 1.76 + 7.1 = 24.0
24.0 (3 sig. fig., but only 1 digit to the right of the decimal 24.0 (3 sig. fig., but only 1 digit to the right of the decimal point)point)
Significant Figures
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Uncertainty in MeasurementUncertainty in Measurement
• 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.”
Rounding rules
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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?
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Dimensional AnalysisDimensional Analysis
• Method of calculation using a conversion factor.
inches
footor
foot
inches
footinches
12
11
1
121
112
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Dimensional AnalysisDimensional Analysis
Example: we want to convert the distance 8 in. to feet.
(12in = 1 ft)
in
ftin
12
18
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Dimensional AnalysisDimensional Analysis
Example: we want to convert the distance 8 in. to feet.
(12in = 1 ft)
ftin
ftin 67.0
12
18
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Dimensional AnalysisDimensional Analysis
ProblemConvert the quantity from 2.3 x 10-8 cm to nanometers (nm)
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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)
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
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Dimensional AnalysisDimensional Analysis
ProblemConvert the quantity from 31,820 mi2 to square meters (m2)
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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)
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
km
m
mi
kmmi 2820,31
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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”.
22
2820,31km
m
mi
kmmi
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Dimensional AnalysisDimensional Analysis
ProblemConvert the quantity from 31,820 mi2 to square meters (m2)
22
2
1
1000
1
6093.1820,31
km
m
mi
kmmi
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Dimensional AnalysisDimensional Analysis
ProblemConvert the quantity from 31,820 mi2 to square meters (m2)
2
26
2
22
1
101
1
5898.2820,31
km
m
mi
kmmi
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Dimensional AnalysisDimensional Analysis
ProblemConvert the quantity from 31,820 mi2 to square meters (m2)
2102
26
2
22 102407.8
1
101
1
5898.2820,31 m
km
m
mi
kmmi
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Dimensional AnalysisDimensional Analysis
ProblemConvert the quantity from 14 m/s to miles per hour (mi/hr).
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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)
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
hr
min
min
s
km
mi
m
km/14 sm
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
hr1
min60
min1
s60
km6093.1
mi1
m1000
km1/14 sm
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Dimensional AnalysisDimensional Analysis
ProblemConvert 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
hrmi
sm
/31
hr1
min60
min1
s60
km6093.1
mi1
m1000
km1/14
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End of Chapter ProblemsEnd 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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