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Oxygen
Carbon Dioxide
Ethylene glycol
Ethanol
Aspirin
Water
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Why Study Chemistry?
It provides an important understanding of our
world and how it works Improvement of health care
Conservation of natural resources
Protection of the environment
Increased food production Development of new materials
It is, by its very nature the central science
Astronomy, atmospheric science, biology, geology,
environmental science, medicine, physics, materialscience, and polymers
The language of chemistry is a universalscientific language
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How Do I Study Chemistry?
It takes lots of practice--homework, reviewing notes,reading the text.
It is different than some other disciplines MICHELANGELO Buonarroti, Italian painter, sculptor andarchitect (1475-1564). If a block of marble were at the frontof this room I suspect we would select Michelangelo to teach
us this art form.Antoine Lavoisier (1743-1794:guillotined) is called theFather of Modern Chemistry but he thinks waters formula isHO. He knows of about a dozen elements, nothing about
polymers, nuclear chemistry, ceramics, etc.
You must study differently for chemistry--study nearlyevery day. The best predictor of your final grade is yourgrade on the first exam.
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B. Classifications of Matter
States of Matter
a gas, a liquid, or a solid
states of matter differ in some of their simple
observable properties gases (vapors) have no fixed volume or shape. They
can be compressed to occupy a smaller volume or
allowed to expand to occupy a larger volume
liquids have a distinct volume independent of thecontainer that they occupy. They assume the shape
of the portion of the container they occupy
solids have a definite shape and a definite volume
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Pure Substances
Most forms of matter are not chemically pure
air
gasoline
Sidewalks
Pure substances have distinct properties and acomposition that does not vary from sample to sample
All substances are elements or compounds elements cannot be decomposed into simpler substances
carbon, helium, iron, oxygen, chlorine, etc.
compounds are composed of two or more elements
Water (H2O) is composed of two elements, hydrogen andoxygen
Mixtures are combinations of two or more substancesin which each substance retains its own chemicalidentity
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Atoms of an element Molecules of an element
Mixture of elements
and a compound
Molecules of a compound
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Some Common Elements and Their Symbols
Carbon C Aluminum Al Copper Cu (fromcuprum )
Fluorine F Barium Ba Iron Fe (fromferrum )
Hydrogen H Calcium Ca Lead Pb (fromplumbum )Iodine I Chlorine Cl Mercury Hg (from hydragyrum )
Nitrogen N Helium He Potassium K (fromkalium )
Oxygen O Magnesium Mg Silver Ag (fromargentum )
Phophorus P Platinum Pt Sodium Na (from natrium )
Sulfur S Silicon Si Tin Sn (fromstannum )
The symbol for each element consist of one or two letters, with the
first letter capitalized.
You will need to know the symbols and names for the first 100 elements
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Compounds
Most elements interact with other elements to formcompounds
Hydrogen burns in oxygen to form water (one O and two Hatoms)
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The observation that the elemental composition of apure compound is always the same is known as the lawof constant composition (law of definite proportions)
Mixtures
Most of the matter we encounter consists of mixtures ofdifferent substances
Each substance in a mixture retains its own chemicalidentity and properties
Mixture composition can vary
a cup of sweetened coffee. chocolate chip cookies. water foundin nature, rocks, wood, cement, steel, etc.
Some mixtures are uniform throughout Homogeneous mixtures or solutions
Some mixtures are not uniform throughout
Heterogeneous mixtures
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C. Properties of Matter
Every substance has a unique set ofproperties characteristics that allow us to recognize and
distinguish one substance from another
Properties of matter can categorized as either
physical orchemical Physical properties can be measured without
changing the identity and composition of thesubstance
Color, odor, density, melting point, boilingpoint, hardness, etc.
Chemical properties describe the way a substancemay change orreactto form other substances
A common chemical property is flammability
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Some properties, such as temperature, meltingpoint, and density, do not depend on the
amount of sample being examinedintensiveproperties.
used to identify substances
Some properties, such as mass and volume, dodepend on the amount of sample beingexaminedextensive properties.
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Physical and Chemical Changes
Duringphysical changes a substances changes
its physical appearance, but not its composition ice melting to become water
water evaporating to become steam
All state changes are physical changes
During chemical changes (chemical reactions) a
substances is changed into a chemically
different substance
propane burning to form carbon dioxide and water
scrambling an egg
a change in state will not revert the substance back
to its original form
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Separation of Mixtures
Mixtures can be separated into their constituent
components mixture components retain their own properties
Take advantage of the differences in the properties
Heterogeneous Mixtures
visual differences
magnetic differences
state differences
Homogeneous Mixtures
Boiling point difference
Polarity differences
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D. Units of Measurement
Many properties of matter are quantitative; thatit, they are associated with numbers
To say that the length of a pencil is 17.5 ismeaningless
The units used for scientific measurements are
those of the
Metric System
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1. SI Units
1960 - international agreement specifying a
particular choice of seven metric units forscientific measurements
SI = Systme International dUnits
SI Base Units
Physical Quantity Name of Unit Abbreviation
Mass Kilogram Kg
Length Meter m
Time Second sa
Temperature Kelvin K
Amount of substance Mole mol
Electric current Ampere A
Luminous intensity Candela cda
The abbreviation sec is frequently used
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Prefixes are used to indicate decimal factions ormultiples of various units
Exponential notation is used to avoid ambiguitywith regard to value certainty, see section 1.8.Learn these prefixes in Table 1.3.
Selected Prefixes Used in the Metric System
Prefix Abbreviation Meaning Example
Giga G 109 1 gigameter (Gm) = 1 X 10 9 m
Mega M 106 1 megameter (Mm) = 1 X 10 6 m
Kilo k 103 1 kilometer (km) = 1 X 10 3 m
Deci d 10-1 1 decimeter (dm) = 0.1 m = 1 X 10 -1 m
Centi c 10-2
1 centimeter (cm) = 0.01 m = 1 X 10-2
mMilli m 10-3 1 millimeter (mm) = 0.001 m = 1 X 10 -3 m
Micro a 10-6 1 micrometer ( m) = 1 X 10 -6 m
Nano n 10-9 1 nanometer (nm) = 1 X 10 -9 m
Pico p 10-12 1 picometer (pm) = 1 X 10 -12 m
Femto f 10-15 1 femtometer (fm) = 1 X 10 -15 m
aThis is the Greek letter mu (pronounced "mew").
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2. Length and Mass
SI base unit oflength is the meter(m)
1 m = 100 cm = 39.37 inches (slightly longerthan a yard)
Mass is a measure of the amount of material inan object.
Mass is different from weight, which dependsupon gravity
SI base unit ofmass is the kilogram (kg)
This base unit is unusual because it uses a prefix,kilo-, instead of the wordgram alone.
Other units of mass are obtained by adding prefixesto the wordgram
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3. Temperature
We sense temperature as a measure of hotness
and coldnessTemperature determines the direction of heat
flow
Heat always flows spontaneously from a substance
at higher temperature to one at lower temperature.The temperature scales commonly employed in
scientific studies are the Celsius and Kelvinscales
The Celsius scale, the everyday scale of temperaturein most countries throughout the world, wasoriginally based on the assignment of 0C to thefreezing poing of water and 100C to its boiling
point at sea level.
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The Kelvin Scale is the SI temperature scale and theSI unit of temperature is the Kelvin (K).
Zero on this scale is - 273.15C, once believed to bethe lowest attainable temperature. Because of this,0K is known as Absolute Zero.
Both the Celsius and Kelvin scales have equal-sizedunitsthat is, a kelvin is the same size as a degreeCelsius.
K = C + 273.15
The freezing point of water, 0C, is 273.15 K
Notice that the degree symbol () is not usedwith temperatures on the Kelvin scale.
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The common temperature scale in the US is theFahrenheit scale
Freezing point of water = 32F
Boiling point of water = 212F
C = 5/9 (F - 32) or F = 9/5 (C) + 32
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4. Volume
The volume of a cube is given by its length
cubed, (length)3
The basic SI unit of volume is the cubic meter
Another common unitof volume is the liter(L),
which equals a cubicdecimeter, dm3.
It is slightly larger than aquart
There are 1000 milliliters (mL)in a liter
Each milliliter is the same volume as acubic centimeter
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Devices Used Most Frequently in Chemistry to Measure Volume
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5. Density
Widely used to characterize substances
Amount of mass in a unit volume of thesubstance
Densitymass
volume=
Densities of solids and liquids are commonly
expressed in grams per cubic centimeter (g/cm3)
or grams per milliliter (g/mL)
The density of water is 1.00 g/ml
Most substances change volume when heated or
cooledDensities are temperature dependent
Assume 25C unless otherwise noted
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Densities of Some Selected Substances at 25C
Substance Density (g/cm3)
Air 0.001
Balsa wood 0.16
Ethanol 0.79
Water 1.00
Ethylene glycol 1.09
Table sugar 1.59
Table salt
Iron 7.9Gold 19.32
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E. Uncertainty in Measurement
There are two kinds of numbers in scientific work:Exact numbers (those whose values are known
exactly)
12 eggs in a dozen, exactly 1000 g in akilogram, and exactly 2.54 cm in an inch
and inexact numbers (those whose values have
some uncertainty)
numbers obtained by measurement
Uncertainties always exist for in measured quantities
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1. Precision and Accuracy
Precision is a measure of how closely
individual measurements agree with oneanother
Accuracy refers to how closely individual
measurements agree with the correct, or true
value.
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2. Significant Figures
Precision of a measured number is indicated
using the concept ofsignificant figures. Those digits in a measured number (or result of a
calculation with measured numbers) that include all
certain digits plus a final one have some uncertainty.
Three measurements (9.12, 9.11, and 9.13 cm)
Avg = 9.12 First two digits (9.1) are certain,
the next digit is estimated, so it has some
uncertainty.
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The greater the number of significant figures,
the greater the certainty implied for the
measurementIn any measurement that is properly reported,
all nonzero digits are significant. Zeros can be
used either as part of the measured value or
merely to locate the decimal point.
Zeros between nonzero digits are always significant
Zeros starting a number are never significant
Zeros ending a number to the right of the decimalpoint are always significant
Zeros ending a number to the left of the decimal
point may or may not be significant
Exponential notation is the solution
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Significant Figures inCalculations
Suppose that 0.0634 g of a compound
will dissolve in 25.31 g of water. How
many grams will dissolve in 100 g ofwater?
10,300
counted by ones = 5 significant figures = 1.0300 x 104
counted by tens = 4 significant figures = 1.030 x 104
counted by 100s = 3 significant figures = 1.03 x 104
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Significant Figure Calculation Rules
Multiplication and Division. When multiplying or dividing measuredquantities, give as many significant figures in the answer as there are
in the measurement with the least number of significant figures.
103.0 x 0.0634 = 6.5302 6.53
2.564 4.522 x 10-2
If the leftmost digit to be dropped is 5, round the last significantfigure up, otherwise simply drop the nonsignificant digits.
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Significant Figure Calculation Rules
Addition and Subtraction. When adding or subtracting measuredquantities, give the same number of decimal places in the answer as
there are in the measurement with the least number of significant
figures.
If the leftmost digit to be dropped is 5, round the last significantfigure up, otherwise simply drop the nonsignificant digits.
10.234 + 0.66 = 16.894 16.89
9.56 = 4.38
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II. Dimensional Analysis
A. This process is called
1. Dimensional analysis (we will use this name)2. Factor-label method, Unit conversion method,
or the Unit Factor Method
Dimensional analysis is a problem solving aid used tohelp ensure that the solutions to problems yield the
proper units.
It provides a systematic way of solving any numericalproblems and of checking solutions for possible errors.
The key to using dimensional analysis is the correct useof conversion factors to change one unit into another.
This method will work for many chemical calculations.When it is not convenient you must still cancel the units
to be certain your answer has the proper dimensions.
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1. A conversion factor is a fraction whose numerator
and denominator are the same quantity expressed
in different units.
2.54 cm and 1 in. are the same length
2.54 cm = 1 in.
2. Two important mathematical realities
Doing the same thing to both sides of an
equation does not change the relationshipMultiplying one does not change the anything
2.54 cm
2.54 cm
1 in.
2.54 cm
== 1 =2.54 cm
1 in.
1 in.
1 in.
=
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3. Since conversion factors are the number one in a
different form, multiplying a measurement and its
units by any number of conversion factors changesthe value and the units but not the reality of the
measurement itself.
How many seconds in a century?
x sec = 1 century 100 years
1 centuryx
365 days
1 yearx
24 hours
1 dayx
60 minutes
1 hourx
60 seconds
1 minutex
1 century = 100 years1 year = 365 days1 day = 24 hours
1 hour = 60 minutes1 minute = 60 seconds
x sec = 3,153,600,000 (3.1536 x 109) sec
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B. Conversion Factors:
Constructed from any two terms that are equal to
each other. If two quantities are equal and if one isthen divided by the other, the quotient equals one
and it is called a Unit Factor or a Conversion Factor.
Remember: any quantity can be multiplied by one
without changing the result.
Examples of Conversion Factors, Memorize these.
a. 1.00 inch = 2.54 cm Length
b. 454 g = 1.00 lb Mass
c. 1.00 L = 1.057 qt Volume
d. 1.00 mL = 1.00 cm3 = 1.00 cc
(learn these first four conversions):
e. 1.00 mol Mg = 24.3 g of Mg
f. Many others that you will learn.
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Volume, like other concepts that will be encountered
throughout the semester, requires the use of
relationships that necessitate the raising ofnumbers to a power, cubing in this specific case
It is imperative to remember to raise both thenumber and the units to the appropriate power
and not just the units
1 in = 2.54 cm 1 in3 2.54 cm3
1 in3 = (1 in)3 = (2.54 cm)3 = 16.39 cm3
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C. Recipe for Dimensional Analysis
1. On the far right, write down the units of the answer.
2. Analyze the information given or known (the units) to
select the proper starting quantity. This information may be
from the problem, the periodic chart, some physical law, or
something you learned.3. Analyze the dimensions (units) of the answer and the
dimensions (units) of the starting quantity to determine the
proper unit factors (conversion factors) to convert the units
given into the units of the answer.
4. This may require several unit factors.
5. Cancel the units and do the numerical calculation.
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Examples:
1. How many inches in 2.57 ft? DO
ANS:
2. How many nm in 3.72 yds? DO
ANS:
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3. A major contributor to global environmental pollution is from coal
burning power plants. Carbon dioxide, a greenhouse gas, is the
major product and all coal contains various amounts of sulfur that
eventually contributes to acid rain. A typical coal burning powerplant burns 2500 tons of coal per day, with a sulfur content of 3%,
and the density of solid bituminous coal is 1346 kg/m3 (solid
anthracite coal has a density of 1506 kg/m3).
a. What volume, in cubit feet, of bituminous coal is burned by atypical coal burning power plant each day?
ANS:
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4. Determine the volume in ft3 of a piece of Pb that has a mass of 13.4
kg, if the density is 11.2 g/cm3. DO
ANS:
5. A gallon of milk weighs 8.00 lbs.
a. What is the mass of one pint in grams? DO
ANS:
b. What is the density of milk in g/mL? DO
ANS:
D l I b ll/D S
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Douglas Isbell/Don SavageHeadquarters, Washington, DC Nov. 10, 1999(Phone: 202/358-1547) Embargoed until 2 p.m. ESTRELEASE: 99-134
MARS CLIMATE ORBITER FAILURE BOARD RELEASES REPORT,NUMEROUS NASA ACTIONS UNDERWAY IN RESPONSE
Wide-ranging managerial and technical actions are underway at NASA's JetPropulsion Laboratory, Pasadena, CA, in response to the loss of the $125 million MarsClimate Orbiter and the initial findings of the mission failure investigation board, whose
first report was released today.
"The 'root cause' of the loss of the spacecraft was the failed translation ofEnglish units into metric units in a segment of ground-based, navigation-relatedmission software, as NASA has previously announced," said ArthurStephenson, chairman of the Mars Climate Orbiter Mission FailureInvestigation Board. "The failure review board has identified other significantfactors that allowed this error to be born, and then let it linger and propagate tothe point where it resulted in a major error in our understanding of thespacecraft's path as it approached Mars.
WEB: http://mars.jpl.nasa.gov/msp98/news/mco991110.html
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