Unit 1 Introduction to Chemistry

Safety

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

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

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

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

LD50 the lethal dosage for 50% of the animals on which the chemical is tested There are various ways an LD50 can be expressed. For example, acetone has the following LD50s: ORL-RAT LD50: 5,800 mg/kg IHL-RAT LD50: 50,100 mg/m3-h SKN-RBT LD50: 20 g/kg

Example Chemical A: LD50 = 3.2 mg/kg Chemical B: LD50 = 48 mg/kg Which is more toxic? Chemical A is more toxic because less of it proves fatal to half of a given population.

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. observation inference uses the five senses involves a judgment or assumption

Observations are also called data. Types of Data Observations are also called data. qualitative data quantitative data -- descriptions -- measurements e.g., clear liquid e.g., 55 L or 83oC

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 (i.e., a recipe) variable: any factor that could influence the result

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

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

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

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

changing one substance into another transmutation: changing one substance into another COPPER GOLD  Philosopher’s Stone we cannot transmute elements into different elements. 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 biochemistry the study of carbon- containing compounds the chemistry of living things physical inorganic measuring physical properties of substances studies everything except carbon e.g., compounds containing metals 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 bulk chemical manufacturing acids, bases, fertilizers **sulfuric acid (H2SO4) = #1 chemical petroleum products fuels, oils, greases, asphalt pharmaceuticals 1 in 10,000 new products gets FDA approval synthetic fibers nylon, polyester, rayon , spandex

are affected by chemistry. All fields of endeavor are affected by chemistry.

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

Manipulating Numerical Data

Graphs

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

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

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

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

Essential Math of Chemistry

Scientific Notation -- used to express very large or very small numbers, and/or to indicate precision (i.e., to maintain the correct number of significant figures) Form: (# from 1 to 9.999) x 10exponent 800 = 8 x 10 x 10 = 8 x 102 2531 = 2.531 x 10 x 10 x 10 = 2.531 x 103 0.0014 = 1.4 10 10 10 = 1.4 x 10–3

Put in standard form. 1.87 x 10–5 = 0.0000187 3.7 x 108 = 370,000,000 7.88 x 101 = 78.8 2.164 x 10–2 = 0.02164 Change to scientific notation. 12,340 = 1.234 x 104 0.369 = 3.69 x 10–1 0.008 = 8 x 10–3 10,000,000 = 1 x 107 6.02 x 1023 = 602,000,000,000,000,000,000,000

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 1023: How to type out 6.02 x 1023: 6 EE . 3 2 6 EE . 3 2 not… WRONG! 6 y x . 3 2 WRONG! or… x 1 6 . 2 EE 3 and not… TOO MUCH WORK. y x 3 2 x 1 6 .

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

1.2 x 105 2.8 x 1019 = 1 . 2 EE 5 9 8 Type this calculation in like this: 4.2857143 –15 Calculator gives… 4.2857143 E–15 or… This is NOT written… 4.3–15 But instead is written… 4.3 x 10–15

7.5 x 10–6 (–8.7 x 10–14) = –6.5 x 10–19 4.35 x 106 (1.23 x 10–3) = 5.35 x 103 or 5350 5.76 x 10–16 9.86 x 10–4 = 5.84 x 10–13 8.8 x 1011 x 3.3 x 1011 = 2.9 x 1023

Essential Math of Chemistry

Units must be carried into the answer, unless they cancel. 5.2 kg (2.9 m) (18 s)(1.3 s) = kg-m s2 0.64 4.8 kg (23 s) (18 s)(37 s) = kg s 0.17

x + y = z x + y = z – y – y x = z – y Solve for x. x and y are connected by addition. Separate them using subtraction. In general, use opposing functions to separate things. x + y = z – y – y The +y and –y cancel on the left, x = z – y leaving us with…

Numerical Example x – 24 = 13 x – 24 = 13 +24 +24 x = 37 Solve for x. x and 24 are connected by subtraction. Separate them using the opposite function: addition. x – 24 = 13 +24 +24 The –24 and +24 cancel on the left, leaving us with… x = 37

( ) F = k x __ 1 k F = k x (or) F = k x k x = F k __ Solve for x. x and k are connected by multiplication. Separate them using the opposite function: division. (or) F = k x k The two k’s cancel on the right, leaving us with… x = F k __

( ) Numerical Example 8 = 7 x __ 1 7 8 = 7 x (or) 8 = 7 x 7 x = 8 7 __ Solve for x. 8 = 7 x ( ) __ 1 7 8 = 7 x x and 7 are connected by multiplication. Separate them using the opposite function: division. (or) 8 = 7 x 7 The two 7’s cancel on the right, leaving us with… x = 8 7 __

( ) ___ x BA = TR H BAH = xTR 1 TR ___ BAH = xTR ___ BAH TR x = Solve for x. ___ x BA = TR H One way to solve this is to cross-multiply. BAH = xTR 1 TR ( ) ___ Then, divide both sides by TR. BAH = xTR ___ BAH TR x = The answer is…

( ) ____ T1 P1V1 = P2V2 T2 1 ____ P1V1T2 = P2V2T1 T2 = P1V1 ______ Solve for T2, where… P1 = 1.08 atm P2 = 0.86 atm V1 = 3.22 L V2 = 1.43 L T1 = 373 K ____ T1 P1V1 = P2V2 T2 1 P1V1 ( ) ____ P1V1T2 = P2V2T1 T2 = P1V1 ______ P2V2T1 T2 = (1.08 atm)(3.22 L) _____________________ (0.86 atm)(1.43 L)(373 K) = 132 K

Conversion Factors and Unit Cancellation

SI Prefixes kilo- (k) 1000 deci- (d) 1/10 centi- (c) 1/100 milli- (m) 1/1000 Also, 1 mL = 1 cm3 and 1 L = 1 dm3

( ) ______ How many cm are in 1.32 meters? equality: 1 m = 100 cm (or 0.01 m = 1 cm) conversion factors: ______ 1 m 100 cm ______ 1 m 100 cm or ( ) ______ 1 m 100 cm 1.32 m = 132 cm We use the idea of unit cancellation to decide upon which one of the two conversion factors we choose.

Again, the units must cancel. How many m is 8.72 cm? equality: 1 m = 100 cm conversion factors: ______ 1 m 100 cm ______ 1 m 100 cm or ( ) ______ 1 m 100 cm 8.72 cm = 0.0872 m Again, the units must cancel.

( ) ( ) ____ ______ How many kilometers is 15,000 decimeters? 10 dm 1 km 15,000 dm = 1.5 km

How many seconds is 4.38 days? ____ ( ) ( ) _____ ( ) ____ 24 h 1 d 1 h 60 min 1 min 60 s 4.38 d = 378,432 s If we are accounting for significant figures, we would change this to… 3.78 x 105 s

Simple Math with Conversion Factors

( ) ( ) ______ ______ Find area of rectangle. A = L . W 4.6 cm = (4.6 cm)(9.1 cm) 9.1 cm = 42 cm 2 . cm cm.cm ( ) ______ 100 cm 1 m Convert to m2. 42 cm2 2 = 0.0042 m2 ( ) ______ 1 cm 10 mm Convert to mm2. 42 cm2 2 = 4200 mm2

For the rectangular solid: Length = 14.2 cm Width = 8.6 cm Height = 21.5 cm Find volume. V = L . W . H = (14.2 cm)(8.6 cm)(21.5 cm) = 2600 cm3

( ) ______ Convert to mm3. 1 cm 10 mm 2600 cm3 3 = 2,600,000 mm3 = 2.6 x 106 mm3 mm and cm differ by a factor of………. mm2 “ cm2 “ “ “ “ “ ………. mm3 “ cm3 “ “ “ “ “ ………. 10 100 1000

Basic Concepts in Chemistry

“what you started with” 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

carbon dioxide methane + oxygen  + water CH4(g) + 2 O2(g)  CO2(g) + H2O(g) 2 

sodium hydroxide sodium + water  hydrogen + 2 Na(s) + 2 H2O(l)  H2(g) + 2 NaOH(aq) 

Law of Conservation of Mass total mass total mass of products of reactants = Pmass = Rmass synthesis: taking small molecules and putting them together, usually in many steps, to make something more complex

Again, the units must cancel. How many feet is 39.37 inches? equality: 1 ft = 12 in applicable conversion factors: ______ 1 ft 12 in ______ 1 ft 12 in or ( ) ____ 1 ft 12 in 3.28 ft X ft = 39.37 in = Again, the units must cancel.