Unit 1 Introduction to Chemistry

Safety

Basic Safety Rules Use common sense. No horseplay. No unauthorized experiments. Handle chemicals/glassware with respect. Others: #1 Rule:

Chemical Burns Chemical burns on feet. Skin burned by chemicals Flammable ReactiveHealth Special

Safety Features of the Lab safety shower fire blanket fire extinguisher eye wash fume hood circuit breaker switch

Material Safety Data Sheet (MSDS) gives information about a chemical -- lists “Dos” and “Don’ts;” emergency procedures --

Laboratory Equipment

Chemical Exposure a one-time exposure causes damage acute exposurechronic exposure damage occurs after repeated exposure reaction to drugs or medication e.g., smoking, asbestos

the lethal dosage for 50% of the animals on which the chemical is tested LD 50 There are various ways an LD 50 can be expressed. For example, acetone has the following LD 50 s: ORL-RAT LD 50 : 5,800 mg/kg IHL-RAT LD 50 : 50,100 mg/m 3 -h SKN-RBT LD 50 : 20 g/kg

Example Which is more toxic? Chemical A is more toxic because less of it proves fatal to half of a given population. Chemical A: LD 50 = 3.2 mg/kg Chemical B: LD 50 = 48 mg/kg

Science

The Functions of Science pure science applied science the search for knowledge; facts using knowledge in a practical way e.g., aluminum strong lightweight good conductor

Science attempts to establish cause-effect relationships. 

risk-benefit analysis weigh pros and cons before deciding Because there are many considerations for each case, “50/50 thinking” rarely applies.

How does scientific knowledge advance? 1. curiosity 2. good observations 3. determination 4. persistence

The Scientific Method

** Key: Be a good observer. observationinference involves a judgment or assumption uses the five senses

Types of Data Observations are also called data. qualitative data quantitative data clear liquid e.g.,e.g., descriptionsmeasurements 55 L or 83 o C

Parts of the Scientific Method Identify an unknown. Make a hypothesis: a testable prediction Repeatedly experiment to test hypothesis. procedure: order of events in experiment variable: any factor that could influence the result (i.e., a recipe)

A Scientific Experiment conclusion: must be based on the data Experiments must be controlled: they must have two set-ups that differ by only one variable

Scientific Law vs. Scientific Theory law: Theory of Gravity, Atomic Theory states what happens tries to explain why or how something happens -- e.g., does not change law of gravity, laws of conservation never violated -- theory: -- e.g., -- based on current evidence

Phlogiston Theory of Burning 1. Flammable materials contain phlogiston. 2. During burning, phlogiston is released into the air. 3. Burning stops when… …object is out of phlogiston, or …the surrounding air contains too much phlogiston. (superceded by combustion theory of burning)

Chemistry

The Beginning The Greeks believed there were four elements. early practical chemistry: household goods, weapons, soap, wine, basic medicine earthwindfire water  ~ ~  ___ 

Alchemy Allegedly, this substance would turn cheap metals into gold. the quest for the Philosopher’s Stone (~500 – 1300 C.E.) (the elixir, the Sorcerer’s Stone) Alchemical symbols for substances… GOLDSILVERCOPPER IRONSAND

transmutation: we cannot transmute elements into different elements. changing one substance into another COPPER GOLD  Philosopher’s Stone In ordinary chemical reactions…

Alchemy was practiced in many regions of the world, including China and the Middle East. Alchemy arrived in western Europe around the year 500 C.E. Modern chemistry evolved from alchemy.

Contributions of alchemists: experimental techniques new glassware information about elements developed several alloys

What is Chemistry? the study of matter and its changes

Areas of Chemistry organic physical inorganic biochemistry studies everything except carbon e.g., compounds containing metals the study of carbon- containing compounds measuring physical properties of substances the chemistry of living things e.g., the melting point of gold

Careers in Chemistry research (new products) production (quality control) development (manufacturing) chemical sales software engineering teaching

The skills you will develop by an earnest study of chemistry will help you in any career field.

The Scope of Chemistry pharmaceuticals nylon, polyester, rayon bulk chemical manufacturing petroleum products synthetic fibers acids, bases, fertilizers fuels, oils, greases, asphalt 1 in 10,000 new products gets FDA approval spandex, **sulfuric acid (H 2 SO 4 ) = #1 chemical

All fields of endeavor are affected by chemistry.

Government Regulation of Chemicals The government regulates chemicals to protect the… OSHA worker FDA USDA FAA CPSC consumer EPA environment

Graphs

Bar Graph shows how many of something are in each category # of students

Pie Graph shows how a whole is broken into parts Percentage of Weekly Income

Line Graph shows continuous change Stock Price over Time you will always use a line graph. In chemistry…

Elements of a “good” line graph 2. axes labeled, with units 4. use the available space 1. title 3. neat

Using the Exponent Key EXP EE

The EE or EXP or E key means “times 10 to the…” How to type out 6.02 x : 6EE y x x EE320y x 32 x not… or… and not… How to type out 6.02 x : 6EE WRONG! TOO MUCH WORK.

Also, know when to hit your (–) sign. (before the number, after the number, or either one)

4.3 x 10 –9 4.3 E –9or 1.2 x x But instead is written… = 1. 2EE Type this calculation in like this: This is NOT written…4.3 – –15 Calculator gives… E–15 or…

–6.5 x 10 – x 10 3 or x x 10 –6 (–8.7 x 10 –14 ) = 4.35 x 10 6 (1.23 x 10 –3 ) = 5.76 x 10 – x 10 –4 = 8.8 x x 3.3 x = 5.84 x 10 –13

Basic Concepts in Chemistry

chemical: any substance that takes part in, or occurs as a result of, a chemical reaction All matter can be considered to be chemicals or mixtures of chemicals. chemical reaction: a rearrangement of atoms such that… “what you end up with” differs from “what you started with” products reactants

methane + oxygen  + H 2 O(g) carbon dioxide O 2 (g)CO 2 (g)CH 4 (g)+  water+ 22 

NaOH(aq) water Na(s)H 2 O(l)H 2 (g)2 sodium 22 hydrogen sodium hydroxide +  + +  + 

Law of Conservation of Mass total mass of productsof reactants P mass = R mass = synthesis: taking small molecules and putting them together, usually in many steps, to make something more complex JENNY