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Welcome to Chem 1050 !!. Mark Fickenscher. Ch 1 Matter & Change. At the end of Chem 1050 you will look like this mad scientist . Chemistry. The study of the composition of substances & the changes they undergo. Question: What isn’t Chemistry? We live in a complex world!! - PowerPoint PPT Presentation
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Welcome to Chem 1050 !!
Mark Fickenscher
Ch 1 Matter & Change
At the end of Chem 1050 you will look like this mad scientist
Chemistry• The study of the composition of substances & the changes they undergo
• Question: What isn’t Chemistry?
• We live in a complex world!!
• Ex: Car – 30 yrs ago what was it made of?
Car Example• Now what is a car made of?
And why?
• Another question: Has chemistry & science in general been “good” for humans? Why or why not?
Chemistry• It is a basic building
block for:• Biology• Physics• Geology
Technology• What is it?
• Defn: Application of knowledge for practical purposes.
• Which came first: science or technology?
Technology• Examples: cooking food, pottery,
metals, fermentation, dyes, drugs from plants.
• No scientific understanding, just application of technology
• What is a more modern example?
Technology• Ex from Roman Empire:
viaducts, aquaducts – fresh water supply and sewage systems in Rome.
• Pb water pipes – what was wrong with this?
Theory• Greeks didn’t test theories only
stated them without proof.• A theory “explains” something in
science.• Science grew slowly out of natural
philosophy – speculated about nature.
Alchemy• Middle ages – scientists equally
comfortable with alchemy and real science.
• Alchemy – no documentation but elements discovered; precious metals, elixers
Alchemy• Technology provided
instruments such as microscopes.
• Frances Bacon (1561-1626) – philosopher and lawyer – science should be experimental and should enrich our lives.
Alchemy & Chemistry• By mid 20th century – a lot
came true.
• Medicines, fertilizers, insecticides, hybrids, clothing.
• Was all of the above good?
Alchemy & Chemistry• Rachel Carson – 1962 book
Silent Spring was about what famous chemical?
• DDT
• Also the introduction of detergents in the 1950’s
Alchemy & Chemistry• Science has lost its luster or has it?
What do I mean by that?
• Back to some history – by late 1800’s the world was on the verge of starvation due to population growth and limited food supply
Fritz Haber• German chemist, WWI worked
on making ammonia easier and more productive for war effort.
• Turned out his methods saved the world from starvation. How did he do it?
• (Equation on board)
Back to Chemistry• Science is based on
observations.• Can’t force nature to suit our
ideas.• Data must be reproducible.• Hypothesis – guess or a test
based on observations.
Back to Chemistry• Humanities – what is beauty?
Truth? This is not science!• In science – hypotheses are
testable.• Science by the way is not fair!• A beautiful idea can be destroyed
by experiments or tests.
Back to Chemistry• Example: The earth is flat • By late 1800’s most everything
had been discovered according to the top scientists of the day. The world clanked or chunked along with huge machines.
Back to Chemistry• Max Planck was a young man
from Germany who was deciding to become a physicist or a mathematician and he was told to do math! He was told that most everything had been discovered by then!
Back to Chemistry• And yet no one could tell you
where a baby came from or how it got started!
• Scientific Law – concise statement
• Ex: Boyle’s Law P1V1= P2V2
Back to Chemistry• Scientific models help explain
complicated things.
• Example of containers of liquid and gas
• Science has to control variables
Chemistry• Chemistry is a central science
• Matter – stuff of everything
• Mass – measure of quantity of something
• Weight – force (gravity) - it changes
Chemistry• Physical Property – physical
characteristic – doesn’t change the substance
• MP, BP, color, hardness, odor• Chemical Property – how
substance reacts with other substances or matter.
Chemistry• Name a chemical property.
• Physical Change – alters the material without changing its composition
• Examples
Chemistry• Chemical Property – changes
the substance into something else – creates new substances
• Rust
• Making rubber
Chemistry• Substance – pure, definite, fixed
composition• Ex: water, NaCl• Mixture – 2 or more substances• Each retains their ID• Can be separated by physical
means.
States of Matter• Solid – definite shape and
volume• Liquid – less tightly packed and
almost incompressible• Gas – takes shape & volume of
container• State also known as a “phase”
Example of States of Matter
Air• Air – is it a substance?
• It is a mixture of substances!
• Homogeneous mixture – same throughout – uniform
• Ex: jello, Kool-Aid
Mixtures• Air
• Beef stew
• Salt water
• Heterogeneous mixture – not uniform
• Ex: salad
More Examples:• Soil or dirt
• Blood
• Milk
• Auto Tire
• Which above are heterogeneous or homogeneous?
Examples of HomogeneousMixtures
• Salt water• Air• Brass – Cu & Zn• Pewter – Sn & Pb
Homogeneous Mixtures• Special Name for above:
Solutions
• All solutions are homogeneous mixtures
Elements & Compounds• Physically separate mixtures into
parts you get pure substances.
• Elements – fundamental substance
• Cannot be broken down into simplier substances
Compounds
• Made up of 2 or more elements
• Can be separated by chemical reactions only not physical change
Compounds
• Fixed composition – chemically combined
• Not a mixture!
• H2O , CO2 , NaCl
• Always the same proportion
Examples
• Water
• 88.8% oxygen
• 11.2% hydrogen
• Always
Examples
• Carbon Dioxide
• 27.3% carbon
• 72.7% oxygen
• Always
Chemical Symbols
• H2O
• Shorthand way of writing chemical formulas of compounds
• Co vs CO element always has lower case 2nd letter (if used)
• C12H22O11
• Sucrose
• NaHCO3
• Sodium Hydrogen Carbonate
• Otherwise known as baking soda
Symbol Rules• First letter is always
capitalized• 2nd letter is always lower
case (if used)
• Each element represented by a symbol
• Now over 118 (?)• 90 found naturally• 1/3 essential for life• Approx. 8 elements account for
98% mass of earth’s crust
Measurements• SI units
• Kg, sec, Kelvin, mol
• Exponential numbers
• Metric handout and important units in metric system
Measurements• Know:• m = meter• K = Kilo = 103 meter• μ = micro =10-6 meter• cm = centimeter = 10-2 meter• mm = millimeter = 10-3 meter
Measurements• Know:
• 1.06 qt = 1 L
• 2.54 cm = 1 inch
• 1 lb. = 454 grams
• 1L = 1000 mL
Example of Metric vs English Systems
Density• d = m/v
• How do you rearrange?
• Examples
• Salt solution has 52.5 mL and a mass of 58.5 grams what is its density?
Density• A metal cube 2.0 cm on a side
has a mass of 89.2 g. What is its density?
• What is the volume occupied by 500.0 g of magnesium?
(from table dMg = 1.738 g/cm3)
Temperature• K = 0C + 273
• 0C x 9/5 + 32 = 0F
• (0F – 32) x 5/9 = 0C
Heat Example
More Ch 1• Air we breathe
• % of gases
• Air is a mixture – homogeneous or heterogeneous?
• 1970 Clean Air Act
More Ch 1• Life on Earth with O2
• O2 – burning, rusting, other corrosion
• Most abundant element in our crust
More Ch 1• CO2 example .0385% in
atmosphere
• How many ppm?
• So out of 1 x 106 molecules of air, 385 are CO2
More Ch 1• Focus on 5 components in air:
• N2 78%
• O2 21%
• Ar < 1%
• H2O 0-5%
• % = pph
More Ch 1• We smell ! • Trace amounts of other gases in
air• Focus on 4 of them as
pollutants• CO• O3
More Ch 1• SO2
• NO2
• Particulate matter
• What are attributes of each?
• EPA developed AQI
• Reported daily in major cities
More Ch 1• Table 1.3 in ch 1
• 50% Americans live in cities of 500,000 or more
• Risk –
• Air Quality vs Risk
More Ch 1• Warnings do not say you will be
affected • Chance or probability• Risk Assessment – evaluating
scientific data & making predictions in an organized manner about probabilities of an occurrence.
More Ch 1• Example – cell phones vs
driving• Risks and benefits• Voice vs text messaging• What about the perception of
risk?• Ex: fear of flying
More Ch 1• Burning Hydrocarbons
• Methane
• Gasoline
• Pollutants from Coal & Autos
• SO2
• Other sources of acid rain?
End of Ch 1