CHEM 200/202. Professor Gregory P. Holland Office: GMCS-213C. All s are to be sent to:

Transcription

1 CHEM 200/202 Professor Gregory P. Holland Office: GMCS-213C All s are to be sent to: My office hours will be held in GMCS-212 on Monday from 12 pm to 2:00 pm or by appointment.

2 ONLINE TOOLS Blackboard: one section for each lab. Links on sidebar to various resources: OWL - online homework and quizzes ebook - a pdf version of the book chemistry New website this semester: sdsuchem200.com

3 ANNOUNCEMENTS Waitlisters: Sections (Gu s Labs), My Lecture, If you have class at 2 PM. Watch the website, working with the registrar, more early next week If you are waitlisted and get in, chem200@mail.sdsu.edu In OWL watch the prep videos prior to doing any assignments (WE KNOW IF YOU HAVE NOT WATCHED THEM) Review Assignments due January 25 th (Chem & Math) HW 1 is due January 26 th (Chapter 1) Lab safety quiz due January 28 th (don t start until after Lab1) Note: OWL Assignments are due by 11:59 PM on due date

4 LABS Lab coordinator: Theresa Carlson For Lab 1, please wear proper attire (no lab protective gear is OK). You must get >60% on the lab safety quiz in order to participate in the Lab 2. For Lab 2, you must wear proper attire and must have protective gear.

5 APPROPRIATE LAB ATTIRE If a student is not wearing any of the following they will not be permitted into the lab: Closed toed and closed heeled shoes (All Labs) Pants, skirts, and dresses must extend below the calf (All Labs) No tank tops or open backs (All Labs) No ripped pants or jeans with holes (All Labs) Lab apron or lab coat (Lab 2 & on) Lab glasses (Lab 2 & on, Safety glasses, not goggles) Gloves (Lab 2 & on)

6 SUPPLEMENTAL INSTRUCTION Study sessions lead by former CHEM 200/202 students that excelled in the previous semesters class. Occur 15 times a week. Free to access, no reporting to faculty. Link to the SI schedule is on blackboard.

7 A LITTLE BIT ABOUT ME Grew up in Queens in NYC (in case you sense a little accent ) Went to college at SUNY Buffalo, BS in Chemistry (first generation college graduate) Went to graduate school at the U of Wyoming, PhD in Chemistry Postdoctoral work at Sandia National Labs, Albuquerque, NM (~3 years) Research Professor in Chemistry at Arizona State University, Tempe, AZ (~9 years) working in magnetic resonance of bio and technological materials Professor in Chemistry at SDSU since Jan 2015

8 WHAT DOES MY LAB DO? Nuclear Magnetic Resonance (NMR) Venom Nanomaterials Characterization Biomembranes Lipid Rafts Biopolymers Spider Silk 5 µm

9 LECTURE OBJECTIVES Chapter 1.1 Chemisty in Context & The Scientific Method. Chapter 1.2 Phases and Classification of Matter Chapter 1.3 Physical and Chemical Properties Chapter 1.4 Measurement - SI Units, Prefixes Chapter 1.5 Measurement Uncertainty - Accuracy/Precision & Sig. Figs. Chapter 1.6 Mathematical Treatment of Measurement Results

10 CHEMISTRY - THE CENTRAL SCIENCE

11 THE SCIENTIFIC METHOD From the perspective of an infant. Observation: Parents pick things up and give them back to me. Hypothesis: If I knock something off the table the parents will pick it up. Experiment: There goes the fork! Model (Theory): Parents will always pick up things that I knock off the table. Further Experiments: Repeat experiment with spoon, bowl, pureed beets New Model (Theory): Parent s don t pick up and give back pureed beets..excellent!

12 THE SCIENTIFIC METHOD Observation: Are reliable measurements. Hypothesis: A proposal to explain the results of the measurements (this may be revised). Experiment: The hypothesis is tested. Model (Theory): Assumptions are used to make a theory that explain the data from the experiments. From the perspective of a scientist Further Experiments: New experiments are tested to see if the model continues to hold true, or if it needs to be modified. If it holds true the theory may become a Scientific Law.

13 DEFINITIONS Matter: anything that has mass and volume - a chair, a book, a molecule, you and me Composition: the simpler substance(s) and amounts that make up matter (e.g. air ~ 78% N2, 21% O2, 0.9% Ar, 0.04% CO2,...) Properties: the physical and chemical characteristics that make each substance unique.

14 MATTER EXISTS IN DIFFERENT STATES

15 PHYSICAL & CHEMICAL PROPERTIES Physical properties: those which identify the substance without interacting with another substance (e.g. color, melting point, density...) Chemical properties: those which identify the substance by it s interactions with, or transformations into, other substance(s) (e.g. flammability, corrosiveness, reactivity,...)

16 PHYSICAL & CHEMICAL PROPERTIES Physical property - melting Chemical property - combustion

17 CHEMICAL PROPERTIES (a) Iron (Fe) rusts when exposed to water and oxygen over long periods of time. (b) Chromium (Cr) the primary component in chrome does not rust.

18 PHYSICAL & CHEMICAL PROPERTIES QUESTION Which is a chemical property of copper? Reddish brown color Reacts with nitric acid Melts at 1083 C Conducts electricity

19 Metals Metalloids Non-Metals Transition Metals

20 DENSITIES OF COMMON SUBSTANCES Substance Physical State Density (g/cm 3 ) Hydrogen Gas Oxygen Gas Ethanol Liquid Water Liquid 1 Table Salt Solid 2.16 Aluminum Solid 2.7 Lead Solid 11.3 Gold Solid 19.3

21 MEASUREMENT UNCERTAINTY How long is the red line?

22 Significant Figures Significant figures have real meanings - they represent how accurately something was quantified or measured. The last number is always the first number that is uncertain. Any numbers beyond that one are purely fictional. The results of mathematical transformations are limited by the number of significant digits.

23 Math & Significant Figures 0 counts as a sig fig when: between numbers and before a decimal place or after numbers to the right of the decimal place. Addition & subtraction: the last common decimal place is the least significant figure. Multiplication & division: the answer is limited to the number of significant digits of the factor with the fewest significant figures. More rules for logarithms and exponents but we won't worry about those.

24 Math & Significant Figures - Three Rules Non-zero digits are always significant. Any zeros between two significant digits are significant. A final zero or trailing zeros in the decimal portion ONLY are significant. For more on significant figure rules and practice see chem team website: (case sensitive)

25 MATH & SIGNIFICANT Addition & Subtraction 83.5 ml ml ml = ml Multiplication & Division 15.6 cm 3 sig figs cm 4 sig figs 0.34 cm 2 sig figs cm 3 = 32 cm 3 FIGURES g g g = g 500 g ml g/ml = 2 g/ml

26 EXACT NUMBERS Exact numbers do not have uncertainty These numbers do not impact the number of significant figures in the calculations 60 min = 1 hour 1000 g = 1 kg 4 people

27 RULES FOR ROUNDING NUMBERS Round UP when: The first digit removed is >5 If the first digit removed is 5 and the preceding number is odd (e.g becomes 23.48). Round DOWN when The first digit removed is <5 If the first digit removed is 5 and the preceding number is even (e.g becomes 23.48).

28 SI UNITS The rational units of measurement. Dimension Unit name Abbreviation Mass kilogram kg Length meter m Time second s Temperature kelvin K Electric current ampere A amount of substance mole mol luminous intensity candela cd

29 SCIENTIFIC NOTATION & PREFIXES Prefix Symbol Word Conventional Scientific - - one deci d tenth centi c hundredth milli m thousandth micro µ millionth nano n billionth pico p trillionth femto f quadrillionth

30 SCIENTIFIC NOTATION & PREFIXES Prefix Symbol Word Conventional Scientific tera T trillion 1,000,000,000, giga G billion 1,000,000, mega M million 1,000, kilo k thousand 1, hecto h hundred deka da ten one

31 NUMERICAL PREFIXES mono - 1 di or bi - 2 tri - 3 tetra - 4 penta - 5 hexa - 6 hepta - 7 octa - 8 nona - 9 deca - 10 undeca - 11 dodeca - 12 Examples: Trimethyltin chloride (CH3)3SnCl Dinitrogen pentoxide N2O5 Tetraphosphorous decoxide P4O10

32 ERRORS IN MEASUREMENTS Random error: ALL measurements have some level of random error, they can be either positive or negative errors. Systematic error: arise from problems in the measurement procedure, they will be either positive or negative, but not both. Systematic errors will also be subject to random error; there will be variations in replicate measurements that have systematic error.

33 PRECISION & ACCURACY Precision relates to how reproducible each measurement is; how close each measurement is to the other measurements. Accuracy relates to how close the measured values are to the true value.

34 PRECISION & ACCURACY (a) These arrows are close to both the bull s eye and one another, so they are both accurate and precise. (b) These arrows are close to one another but not on target, so they are precise but not accurate. (c) These arrows are neither on target nor close to one another, so they are neither accurate nor precise.

35 PRECISION & ACCURACY 50 Sample Mass (g) Trial 1 Trial 2 Trial 3 Trial 4 Student A Student B True value (30 g) Systematic error: Student B Random error: Both Students Better precision: Student B Better accuracy: Student A

36 TEMPERATURE SCALES Kelvin (K) - The Absolute temperature scale, begins at zero and only has positive values Celsius ( C) - The principal scientific temperature scale Fahrenheit ( F) - Not used scientifically, used in some countries for weather reports. Relative temperatures: Water freezes at: 32 F 0 C K Water boils at: 212 F 100 C K