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