Intro to Chemistry, the Scientific Method, and Measurement

1. Intro to Chemistry, the Scientific Method, and Measurement

2. Why Study Chemistry?JOKES OF COURSE!! •  What do you do with a sick chemist?  If you can't helium, and you can't curium, then you might as well barium. • Did you hear oxygen went on a date with potassium? It went OK • Two electrons were walking around and bumped into one another. One said, “Oh no I’ve lost an electron”. The other said, “Are you positive?” • Do you have 11 protons? 'Cause you're Sodium fine!

3. Dihydrogen Monoxide • Each year, Dihydrogen Monoxide is a known causative component in many thousands of deaths and is a major contributor to millions upon millions of dollars in damage to property and the environment. Some of the known perils of Dihydrogen Monoxide are: • Death due to accidental inhalation of DHMO, even in small quantities. • Prolonged exposure to solid DHMO causes severe tissue damage. • Excessive ingestion produces a number of unpleasant though not typically life-threatening side-effects. • DHMO is a major component of acid rain. • Gaseous DHMO can cause severe burns

4. Why Study Chemistry? D30 Spray on Clothing • Produce new materials • New sources of energy • Medicine • Criminal investigations • Weapons Liquid Body Armor

5. Learning Chemistry • Fair amount of memorizing • Learn the core curriculum • Problem Solving • Get information out of the text

6. What is Chemistry? • The science that deals with the materials of the universe and the changes that these materials undergo • Sometimes called the “central science” – most phenomena in the world involve chemical changes • Photosynthesis & respiration • Combustion • Food production • Memory storage • Looks at the microscopic world – molecules and atoms

7. What is Chemistry • There are 5 different areas of chemistry • Organic – the study of all chemicals containing carbon • Inorganic – the study of chemicals that, in general, do not contain carbon • Biochemistry – the study of processes that take place in living organisms • Analytical chemistry – the area of study that focuses on the composition of matter (ex: measuring carbon dioxide in winter) • Physical – the area that deals with the mechanism, rate, and energy transfer that occurs when matter changes.

8. Seven Steps of Scientific Method Identify the Problem Make recommendations Formulate Hypothesis Draw Conclusions Conduct Experiments Analyze Data Collect Data

9. The Scientific Method • Question (or problem) - What is the main topic of your exploration? • Research • In this step, you find out what everybody else knows about your topic already. • You need to look at credible sources to find this information. • Try to find out something about your topic that nobody knows the answer to, or at least something that you do not know the answer to.

10. The Scientific Method 3. Hypothesis - A possible explanation of events or a possible answer to your question. - Your hypothesis should not be a random guess, it needs to be based on your research. - There are two types of hypotheses: - Null Hypothesis (H0), which states that there will be no difference between the control group and the experiment group. In other words, nothing will happen. (more professional) - Alternate Hypothesis (HA), which is your prediction of what will happen in the experiment. (common)

11. The Scientific Method 4. Experiment - This is the step where you try and find the answer to your question. - You need to briefly list your materials and methods. - You need to write out the steps you will take to perform your experiment. - All experiments must be divided up into two groups: experiment and control. - In the experiment group, you add different variables (one at a time) to see how they alter the experiment (called independent variables). Besides the different variables in each test, EVERYTHING ELSE MUST BE THE SAME! - In the control group, you perform the same experiment, but you add no variables. The result here is what you compare everything else to. - You must record your results. These results must be measurable. The things you measure are called dependent variables. Generally, you only measure one dependent variable per experiment.

12. The Scientific Method 5. Record and Analyze Data - Make sure to keep good records of your results. - Put your data into a table, graph, chart, etc. so you can compare your results easily. - If you get serious, you need to analyze your data using a statistical test.

13. The Scientific Method 6. Conclusion - Must refer back to your hypothesis. - If you used an alternate hypothesis, you either say that your hypothesis was right, or it was wrong. - If you used a null hypothesis, you need to say that you either proved your hypothesis wrong, or you failed to prove your hypothesis wrong (it was right). 7. Retest / Application / Publish Results - In this section, mention any questions that you came up with because of your experiment, anything you did wrong, etc. - Also, mention why anyone should care about your results (you MUST care) and how they could apply them to their lives.

14. SCIENTIFIC METHOD • The scientific method has been used many times! Each day scientists use this proven process. • Today, the method is classified into two areas: basic research and applied research. • Basic: • Investigates why or how • Applied: • Uses discoveries made in basic research to help in practical ways.

15. World War Z • How did the scientific method apply to this movie? • How was basic and applied research used?

16. Food Spoilage • Pretend you lived in 1700’s when there was no fridge to keep food good… use the scientific method to come up with a solution.

17. Canning! • In 1795,Nicholas Appert put food into a bottle and heated in in a warm bath to kill the microorganisms. • He received $12,000 for his discovery.

18. The Scientific Method • Claude Ville – • The scientific method is just “organized common sense” • Situations you’d use common sense: • You get sick and require medical attention. A neighbor suggests you see her friend who cures disease spiritually. • Your boss at work assigns you to clean some black gunk off the floors, but doesn’t tell you how. • Your pet fish doesn’t look too hot lately. It stays in the bottom corner of the tank and rarely heats.

19. Observing vs. Inference • Science is based on evidence. Two different form of evidence • Observation: Use of the senses to describe something • An outward sign of something that • furnishes proof • Example: • That cow is black & white and smells

20. Observing vs. inference • There are no scientific observations based on inference. • Inference: An assumption derived and stated as a conclusion based on evidence. • Example: • Judy was smiling; I could tell she was having a good time.

21. Example • What evidence do you see? • What inferences can you make? • http://www.maniacworld.com/Spinning-Silhouette-Optical-Illusion.html • Total Blackout

22. Fact vs. Inference Fact: a thing that has already happened or is thought to be true Infer: to derive or conclude by reasoning from something known or assumed Examples: There is a tree in the picture The tree is tall There are three wolves The wolves are hungry The wolves are picky eaters The wolves are holding a paper The wolves are going to help natural selection move along quicker

23. METRIC SYSTEM

24. Metric System Le Systemé International (official name) Abbreviated as “SI system” Also called the metric system in US (unofficial name) Official system of measurement in every major country in the world but one.

25. Today’s definition of a meter The distance that light travels in a very small amount of time in a vacuum (in 1 / 299,792,458 sec) This is a good definition because the speed of light never changes (c = 3 x 108 m/s) French scientists created a set of prefixes that multiplied or divided the meter by fractions of 10 to make smaller and greater units of measurement III. Units of Measurement

26. Prefixes Prefix Abbreviation How it Equates Tera……………………………………..T………………1 Tm = 1,000,000,000,000 m Giga…………………………………….G………………1 Gm = 1,000,000,000 m Mega …………………………………..M………………1 Mm =1,000,000 m Kilo……………………………..k.……….... 1 km = 1,000 m Hecto ………………………….h.………….1 hm = 100 m Deka………………………….da….…….…1 dam = 10 m Basic Unit (Meter, Liter, Gram)..m, L, g…... 1 m = 1 m deci………………………..….d……….…. 1 dm = 0.1 m centi……………………..……c……..…….. 1 cm = 0.01 m milli……………………………m…….…….. 1 mm = 0.001 m micro…………………….…...............µ………....………1 µm = 0.000001 m nano ………………….………………n………………….1nm = 0.000000001 m pico……………………………………p…….…………….1pm = 0.000000000001 m

27. Energy Joule J

29. IV. Uncertainty in Measurement • Precision: Measurements are close to one another • Accuracy: Measurements are close to accepted value

31. V. Working with Numbers • Significant Digits : refers to all certain numbers in a measurement and one estimated number

32. Significant Figures • All nonzero digits are significant. • 123400 • Zeroes between two significant figures are themselves significant. • 120034 • Zeroes at the beginning of a number are never significant. • 0.001234 • Zeroes at the end of a number are significant if a decimal point is written in the number. • 12.3400

33. Two Sig Figs Examples One Sig fig 49000.00002 3.70.005968,0005.0 Three Sig Figs • 9.640.0036099,9008.0

34. How many sig figs? 100 100. 10302.00 0.001 10302 1.0302x104 1 3 7 1 5 9

35. Significant Figures • When addition or subtraction is performed, answers are rounded to the least significant decimal place. • 44.44 – 22.2 = ???? • When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation. • 3 x 2.2 = ????

36. Scientific Notation • Makes small and large numbers easier to work with • Two parts • Change to a number between 1 & 10 • Use a power of ten for decimal movement • Turns 1200 to 1.2 x 103 • What would 12000000 turn to????

37. Percents and Percent Error • % = amount have x 100 amount possible • 8 people out of 10 are here today. What percent is that? • % error= measured value – accepted x100 accepted value • Boiling point is 100°C. You measure it at 98°C. What is your percent error?

38. Ratios in Calculations • Speed = length time • Density = mass volume

39. VI. Problem Solving • Dimensional Analysis: Technique for converting between units • Unit equality: tells how units are related (see pg. 130) • Conversion factors: a unit equality written as a fraction

40. Example: Change 250 gals into Liters • Step 1: Find a unit equality 1 gal = 3.785 L • Step 2: Write conversion factors 1 gal/ 3.785 L 3.785 L/ 1 gal • Step 3: Choose correct conversion factor -cancel units

41. Step 4: Solve • 250 gals x 3.785 L = 950 L 1 gal • 5 inches = ??? Centimeters • 10 meters = ??? kilometers

42. Lengthy Conversions: Change 5.0 hours into seconds • Step 1: 1hr. = 60 min. 1 min. = 60 s • Step 2: 60 min./ 1 hr. 1 hr./ 60 min. 1 min./ 60 s 60 s/ 1 min. • Step 3 & 4: 5.0 hr. x 60 min. x 60 s = 18,000 s 1 hr. 1 min.