1. 1 Welcome to CHEM 101: Survey of General Chemistry Prof. Abdi Mohamed Contact Info: Page 1 of Syllabus

2. 2 Chem 101, Welcome on Board! Lecture 1 Outline Introduction Course Organization and Procedures The Scientific Method Measurement and Scientific Notation Measured Numbers and Significant Figures Problem Solving Dimensional Analysis Density Problems Temperature Conversions

3. 3 Course Organization and Procedure Meetings: Tuesdays: AS 1519, Labs days Thursdays: AS 1521, All lecture (Note, Different) Your Course Grade Will be Computed: 3 midterms (lowest dropped)200 pts33% Cumulative Final200 pts33% 6 Quizzes (10 pts each, lowest dropped)50 pts8% 8 Home works (lowest dropped)35 pts6% 8 labs (10 pts each)80 pts13% Group Presentation20 pts3% Subjective Evaluation15 pts3%

4. 4 Past Student Performance Grading Scale Based on percent overall points (see syllabus, page 4)… No curving

5. 5 Lecture Format Active Learning: Get Engaged Why group work? Why active learning? Warm-up questions or quiz~ 5–10 minutes Short lecture~ 15 minutes Group activity~ 10 minutes Second Short lecture~ 15 minutes Active Learning (Individual/pair)~ 10 minutes

6. 6 Comments from Prev. Quarters. My Philosophy: Getting students engaged on course content facilitates learning and provides opportunities to correct misconceptions early on. Research on learning: students need to be active for meaningful learning to transpire. “It made me actually work with what I had just learned instead of listening and not really paying that good of attention. They really helped me.” “I learned this way the best.” Not for everyone …Some hate it! (~ 5 to 10%)

7. 7 Feeling Towards Chemistry “Chemistry was my last pre-req class and I put it off to the end because I thought I would be horrible at it and that I would hate it.” “Chemistry is not for me.” C’mon now! Key… Such feeling my inhibit your ability to earn higher grade (FYI, my sister also hates chemistry and my brother tells me, “You study chem what?) “Neither of these turned out to be true.” “I enjoyed learning chemistry.”

8. 8 What you don’t have to worry about in this class … In the past, you may have memorized formulas? Forget about that All formulas will be available to you during exams You are allowed to bring your own 4 x 6” index card to all the midterms You are allowed to bring 8.5 x 11” sheet to the final exam Applied knowledge, not memorization

9. 9 The Scientific Method: Overview Four Steps: 1.Observation 2.Hypothesis 3.Experiment 4.Theory

10. 10 The Scientific Method: Overview

11. 11 Everyday Scientific Thinking Observation: The sound from a CD in a CD player skips. Hypothesis 1: The CD player is faulty. Hypothesis 2: The original CD has a defect. Experiment 1: When I replace the CD with another one, the sound from this second CD is OK. Experiment 2: When I play the original CD in another player, the sound still skips. Theory: My experimental results indicate the original CD has a defect.

12. 12 Example From My Own Research Work Observation:Malaria parasites cannot convert folate compounds (example folic acid) to their polyglutamate forms Hypothesis 1:Parasites lack the enzyme that converts folates to polyglutamate form Hypothesis II:Compounds are not taken up by the parasites (transport problem) Experiment I:Assayed activity of the enzyme that carries out folate polyglutamylation. Parasites readily converted folic acid to its polyglutamate form Theory:Malaria parasites are able to convert folates to their polyglutamate form

13. 13 Measurement and Scientific Notation Measurement gives us three things: 1) Value 2) Unit (dimension) 3) error (uncertainty) In chemistry we  Measure quantities.  Do experiments.  Calculate results.  Use numbers to report measurements. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

14. 14 Stating Measurements In every measurement, a number is followed by a unit. Observe the following examples of measurements: Number and Unit 35 m 0.25 L 225 lb 3.4 hr

15. 15 Units in the Metric System In the metric and SI systems, one unit is used for each type of measurement: MeasurementMetricSI Lengthmeter (m)meter (m) Volumeliter (L)cubic meter (m 3 ) Massgram (g)kilogram (kg) Timesecond (s)second (s) TemperatureCelsius (  C)Kelvin (K)

16. 16 Some Units You Should Know  The inside back cover of your text lists some useful conversion factors. That page will be available to you during exams, but it is good idea to be familiar with these units anyway. Length: 1 meter (m) = 100 centimeters (cm) 1 inch (in) = 2.54 cm (exact) Volume: 1 liter (L) = 1000 milliliters (mL) Mass: 1 kilogram (kg) = 1000 grams (g) 1 g = 1000 mg 1 kg = 2.20 Ib

17. 17 Prefixes and Scale  You should definitely learn this inside out. Again, these prefixes are given in the inside back cover of your text, which should be available to you on exam dates.

18. 18  A very large or a very small number can be expressed as a number between 1 and 10 and power of 10  Power of 10 can be either positive or negative. coefficient power of ten coefficient power of ten 1.5 x 10 2 7.35 x 10 -4  To write a number in scientific notation, the decimal point is placed after the first digit.  The spaces moved are shown as a power of ten. 52 000. = 5.2 x 10 4 0.00378 = 3.78 x 10 -3 4 spaces left 3 spaces right The Scientific Notation

19. 19 Comparing Numbers in Scientific and Standard formats Here are some numbers written in standard format and in scientific notation Number in Standard Format Scientific Notation Diameter of the Earth 12 800 000 m1.28 x 10 7 m Mass of a human 68 kg 6.8 x 10 1 kg Length of a virus 0.000 03 cm3 x 10 -5 cm

20. 20 Pause: Group Activity, On-the-Board Problem Session  Group activity: all groups work on problems on group activity 1 worksheet, problems 1-3  While working on the problems, ask if you have any questions. I’m more than happy to help

21. 21 Measured Numbers  Two types of numbers: 1) Measured numbers: obtained by measuring quantities 2) Exact numbers: obtained by counting, defined numbers Come up with examples involving measured number and exact numbers: Measured NumbersExact Numbers

22. 22 Significant Figures (SF) in Calculations: A Guided-Inquiry Exercise  Study the following examples and determine the rules for rounding off numbers. First, what does it mean to round a number?  5.304 becomes 5.3 when rounded  110.548 becomes 110.5 when rounded Okay, so what is the rule for rounding? The rule is:

23. 23 Determining Significant Figures TABLE 1.4 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

24. 24 All non-zero numbers in a measured number are significant. MeasurementNumber of Significant Figures 38.15 cm4 5.6 ft2 65.6 lb3 122.55 m5 Counting Significant Figures

25. 25 Sandwiched zeros  Occur between nonzero numbers.  Are significant. MeasurementNumber of Significant Figures 50.8 mm3 2001 min4 0.0702 lb3 0.40505 m 5 Sandwiched Zeros

26. 26 Leading zeros  Precede non-zero digits in a decimal number.  Are not significant. Measurement Number of Significant Figures 0.008 mm1 0.0156 oz3 0.0042 lb2 0.000262 mL 3 Leading Zeros

27. 27 Trailing zeros  Are zeros at the right end of number  Are significant ONLY if the number contains decimal  If the number has NO decimal, these are NOT SF MeasurementNumber of Significant Figures 25000 cm 2 2.00 kg3 48 60.0 mL5 25 005 000 g 5 480.3 Trailing Zeros

28. 28 Significant Figures in Scientific Notation In scientific notation  All digits including zeros in the coefficient are significant. Scientific NotationNumber of Significant Figures 8 x 10 4 m1 8.0 x 10 4 m2 8.00 x 10 4 m3

29. 29 State the number of significant figures in each of the following measurements: A. 0.030 m B. 4.050 L C. 0.0008 g D. 2.80 m Consult with someone sitting next to you. Learning Check

30. 30 A. Which answer(s) contains 3 significant figures? 1) 0.47602) 0.00476 3) 4.76 x 10 3 B. All the zeros are significant in 1) 0.00307 2) 25.300 3) 2.050 x 10 3 C. The number of significant figures in 5.80 x 10 2 is 1) one2) two3) three Learning Check

31. 31 In which set(s) do both numbers contain the same number of significant figures? 1) 22.0 and 22.00 2) 400.0 and 4.00 x 10 2 3) 0.000015 and 150 000 Learning Check: You Decide

32. 32 Significant Figures (SF) in Calculations: A Guided-Inquiry Exercise  Look at the following example involving multiplication or division: M/D:110.5 x 0.048 = 5.304 = 5.3 (rounded) 4 SF 2 SF calculator 2 SF How did you determine how many sig. figs our answer should have?  Now, what about addition or subtraction: here is an e xample: A/S:110.5+ 0.048=110.5 (rounded) How is sig. figs in final answer determined?

33. 33 Pause: Think Aloud Pair Problem Solving (TAPPS)  Work with some one sitting next to you on ALE 1 worksheet, problems 1-5. YOU HAVE 5 MINUTES  Alternative in answering the questions  One of you solves one problem out-load, sharing your thinking process as you solve the problem with your partner; the other listens, giving you feedback as necessary. Start with problem 1  On the next problem, switch roles. The listener become problem-solver and vice versa

34. 34 Pause: Individual Learning Exercise Work on your own problems 6-10 of ALE 1. You have 5 minutes. Go. Now, check your answers with someone sitting next to you. Reconcile any differences you may have

35. 35 Problem Solving: Dimensional Analysis  Trick is to identify correct equivalent statement(s) 1 m = 1000 mm 1 lb = 16 oz 2.20 lb = 1 kg  Obtain fraction from equality; write as numerator and denominator (ratio)  Ratio can be inverted to give two conversion factors for each equality 1 in. And 2.54 cm 2.54 cm 1 in.  Correct conversion factor cancels some units and leaves desired units  When done check for SF and SENSE

36. 36 Table 1.9: Some Common Equalities Quick examples: 1) Convert 6 hours to second. (2) How many m in 524 cm?

37. 37 Problem Solving: Density Density  Compares the mass of an object to its volume.  Is the mass of a substance divided by its volume. Density expression D = mass = g or g = g/cm 3 volume mL cm 3 Note: 1 mL = 1 cm 3  Table 1.10 shows densities for common materials

38. 38 Pause: Group Activity Exercise  Group activity: all groups work on ALE 1 worksheet, problems 11-18, skip # 15  While working on the problems, ask if you have any questions. I’m more than happy to help

39. 39 Problem Solving: Temperature Conversions Temperature scales  Fahrenheit ( o F) Celsius ( o C) Kelvin (K)  Have reference points for the boiling and freezing points of water. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

40. 40 Temperature Conversion Formulas  On the Fahrenheit scale, there are 180°F between the freezing and boiling points and on the Celsius scale, there are 100°C, thus a ratio of 1.8 o F/1 o C  Zero points are different  Conversion Factors T F = 1.8 T C + 32  T C = T K - 273 T K = T C + 273

41. 41 Pause: Individual/Group Learning Exercise  Work on problems 4-9 on group activity on your own first, then work as group on the same problems  While working on the problems, ask if you have any questions. I’m more than happy to help

42. 42  Write the initial and final units.  Write a unit plan to convert the initial unit to the final unit.  Write equalities and conversion factors.  Use conversion factors to cancel the initial unit and provide the final unit. Unit 1 x Unit 2 = Unit 2 Unit 1 Initial x Conversion= Final unit factor unit Dimensional Analysis: An In-depth Look

43. 43 Setting up a Problem How many minutes are 2.5 hours? Initial unit= 2.5 hr Final unit=? min Plan=hr min Setup problem to cancel hours (hr). Initial Conversion Final unit factor unit 2.5 hr x 60 min = 150 min (2 SF) 1 hr Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

44. 44 A rattlesnake is 2.44 m long. How many centimeters long is the snake? 1) 2440 cm 2)244 cm 3)24.4 cm Pause: TAPPS Exercise

45. 45  Often, two or more conversion factors are required to obtain the unit needed for the answer. Unit 1 Unit 2Unit 3  Additional conversion factors are placed in the setup to cancel each preceding unit Initial unit x factor 1 x factor 2 = Final unit Unit 1 x Unit 2 x Unit 3 = Unit 3 Unit 1 Unit 2 Using Two or More Factors

46. 46 How many minutes are in 1.4 days? Initial unit: 1.4 days Factor 1 Factor 2 Plan: days hr min Example: Problem Solving

47. 47  Be sure to check your unit cancellation in the setup.  The units in the conversion factors must cancel to give the correct unit for the answer. What is wrong with the following setup? 1.4 day x 1 day x 1 hr 24 hr 60 min Units = day 2 /min is not the unit needed Units don’t cancel properly. Check the Unit Cancellation

48. 48 A bucket contains 4.65 L of water. How many gallons of water is that? Unit plan: L qt gallon Equalities:1.06 qt = 1 L 1 gal = 4 qt Pause Group Work

49. 49 If a ski pole is 3.0 feet in length, how long is the ski pole in mm? More Group Work

50. 50 If your pace on a treadmill is 65 meters per minute, how many minutes will it take for you to walk a distance of 7500 feet? Individual Learning Check