Chem 121 General Chemistry

1. Chem 121 General Chemistry Instructor: Spencer Anthony-Cahill Office CB440 Office hrs: TBA e-mail: sacahill@chem.wwu.edu http://atom.chem.wwu.edu/sacahill/121

2. Chem 121 General Chemistry Lecture: MTRF 12-12:50am in SL 120. Ebbing and Gammon 9th Ed Get ATUS login for campus computers Lab: M 2-4:50pm, W 11am-1:50pm Get Lab Manual online Get safety goggles First lab meeting Mon 9/27 or Wed 9/29 Complete prelab assignment prior to the lab

3. Chem 121 Exams/Grading 538 points possible three midterms @ 75 pts each Cumulative Final exam @ 150 pts 4 online homework assignments (73 pt total) Labs (90 pt total) Grade on a curve if necessary where median grade is C/C+ To pass you must complete all labs

4. Chem 121 General Chemistry You will need a calculator that has exponent and log functions. Most of the problems in the text and on exams require familiarity with algebra and exponential equations. The Tutorial Center (OM 387) can offer assistance to those students who need to brush up on these skills.

5. Chem 121 General Chemistry Schedule of lecture topics and labs is on the course web site. The best preparation for exams is working homework problems from the text and the online homework. If your notes are unclear, if you are struggling with the homework, if you feel overwhelmed� COME TO OFFICE HRS!

6. Chem 121 Course Content This introductory course focuses on three fundamental chemical concepts: - stoichiometry (the mole) (solve quantitative problems in chemistry) - atomic and molecular structure (rationalize/predict chemical reactivity) - Chemical bonding (the basis for understanding the structures of molecules)

7. The Scientific Method observation

8. The Scientific Method: Summary The �Scientific Method� is the systematic investigation of natural phenomena where: observations are explained in terms of general scientific principles hypotheses are tested by further experimentation sufficient empirical support elevates hypothesis to theory or natural law

9. In Science is there ALWAYS a �Right� answer? most of the calculations you will encounter in this course (i.e., the homework problems and exams) have �right� answers in real life researchers investigate questions for which there is no known answer- they propose a �best� explanation

10. In Science is there ALWAYS a �Right� answer? As a scientist, you must be able to convince yourself and your peers that your interpretation is sound given the accepted body of scientific knowledge

11. Measurement (quantitation) is central to chemistry metric: (noun) a standard of measurement -metric: (suffix) of or relating to an art, process or science of measurement metric: (adj) of, relating to, or using the metric system

12. The Metric System of measurement (see Table 1.2) DIMENSION COMMON UNIT SYMBOL mass gram g length meter m time second s temperature kelvin or K deg Celsius �C volume liter L

13. The Metric System:metric prefixes Prefix Symbol Multiple Example nano n 10-9 nm (molecule size) micro m 10-6 mm (cell size) milli m 10-3 mL (flu shot) centi c 10-2 cm (ski length) kilo k 103 kg (weights) mega M 106 MW (power) giga G 109 GB (memory) prefix * base unit = multiple * base unit See Tables 1.1 and 1.2 p 19

14. SPEED LIMIT 188,000 (is this fast or slow?)

15. SPEED LIMIT 188,000 furlongs per fortnight

17. How confident are we in our measurements? are they ACCURATE? conformity to standard or true value are they PRECISE? reproducible, within error tolerances How many of the numerals in the measurement are SIGNIFICANT DIGITS

20. Significant Figures (or Sig Figs) For measured values: report the digits that can be accurately measured, plus a digit that is uncertain (limited by equipment, interpolation etc.) For calculated values: a calculated value can have no more Sig Figs than the least number of them in the data.

21. Significant Figures (or Sig Figs) Rules for determining Sig Figs differ for addition/subtraction vs. multiplication/division For * and � calculations, the final calculated value can have no more sig figs than the least number of them in the data used for the calculation For + and - calculations, the final value is limited by the data which has the greatest uncertainty

22. Significant Digits (or Sig Figs) non-zero digits are assumed to be significant some zeros are significant, others are not: all zeros that fall between sig figs are significant zeros to the right of the decimal point for values >1 are significant zeros to the left of non-zero digits in values <1 are not sig figs

23. Physical vs. Chemical Changes Physical Change = change in the FORM of matter, but not its CHEMICAL COMPOSITION Chemical Change = change in the CHEMICAL COMPOSITION of matter

26. Physical Changes: Charles� Law For a given amount of gas at constant pressure, the volume of the gas is proportional to the temperature of the gas V = c * T

27. Balloons in liquid nitrogen What happens to the balloon when it is transferred from liquid nitrogen (-195.8 �C) to the outside environment (about 23 �C) in the lecture hall (or vice versa)? Why does this happen? Does Charles� Law explain the observations?

29. Properties of matter �physical� properties: what is the physical nature of the matter? For example: color, odor, physical state (liquid, gas, solid), melting/boiling point, tensile strength, density... �chemical� properties: what is the �reactivity� of the matter (e.g. flammability, oxidizing agent, etc.)

30. Density density = mass per unit volume d = mass/volume = g/mL

31. Density The density of liquid water is defined as exactly 1 g/mL at 4 �C. at other temperatures between 0 and 100 �C the density of liquid water is very close to 1 g/mL.

33. Density matter with lesser density than water will float matter with greater density than water will sink,

36. Elements, Compounds and Mixtures Element: �a constituent part; the simplest principle of a subject of study� (Webster) Elements can not be decomposed into simpler parts by chemical reactions Compounds are made up of two or more elements that can be decomposed chemically, but not separated physically Mixtures are made up of two or more elements or compounds and can be separated physically

39. Law of Conservation of Mass In chemical reactions, the total mass remains constant. Starting mass = final mass Mass of reactants consumed in a chemical reaction = mass of products generated in that reaction

43. Law of Constant Composition A pure compound always contains defined proportions of elements, regardless of its source. e.g. pure water is 11.2% H and 88.8% O by mass

44. Law of Constant Composition pure water is 11.2% H and 88.8% O by mass