Chemistry WarmUp Copy ALL of these assignments into your binder Including dates, WarmUps, InClass assignments AND page numbers! August WarmUp: Agenda and complete egg in a bottle lab report InClass: Safety Contract reviewInClass: Lab Bubbles p23 Homework: Read and take notes 1.3 p25 q18-25DUE NEXT CLASS Setpember 1 WarmUp: Hypothesis/Procedure/Observations InClass: Introduction to Dimensional Analysis Homework: Read 1.4 answer q26-27p30DUE NEXT CLASS September 2-3 WarmUp: Scientific Method and the Bubbles Lab Revisited InClass: An Experimental Approach to Science p21TE InClass: Self-assess bubbles lab Quiz: Scientific Method ch Lab: Using the metric system Homework: Read 2.1 answer q3-7DUE NEXT CLASS As soon as you finish copying these assignments: Carefully read over and complete your Egg in a Bottle lab report. Compare your use the rubric to assign yourself a grade.

Announcements SLAC: LEADING THE CHARGE: Exotic New Materials for Future Devices September 28th7:30-8:30 For extra credit (10 homework or inclass points) turn in Program Your notes signed by the presenter or organizer. EYH: October 9, 2010 UCSC

Chapter 1 Introduction to Chemistry

Chapter 1 Introduction to Chemistry

What is Chemistry? Study of matter composition, properties, & changes Applied chemistry attain goals Pure chemistry gather knowledge for knowledge’s sake

Why study Chemistry Explain the natural world –Why? Prepare for a career –Directly- in a lab –Indirectly- problem solving and thinking skills Be an informed citizen –Vote –Don’t get scammed

1.3 Alchemy Forerunner of chemistry Mystical- search for perfection Practical- developed glassware and techniques used today Tried to change elements Faulty assumptions and lack of logic led them astray

Scientific Method A way of solving problems or answering questions. Starts with observation- noting and recording facts Hypothesis- possible explanation of a set of observation –based on research –and previous knowledge

Scientific Method Experiment- designed to test the hypothesis only two possible answers –hypothesis is right –hypothesis is wrong Generates data -observations from experiments. Modify hypothesis - repeat the cycle

Scientific Method

Variables Controlled experiment- one thing is changed. Manipulated variable- What you change or control directly –Also called independent variable Responding variable – What changes as a result. No direct control –Also called dependent variable

13 Origin of Life

14 Aristotle (384 –322 BC) Proposed theory of spontaneous generationProposed theory of spontaneous generation Also called abiogenesisAlso called abiogenesis Living things can arise from nonliving matterLiving things can arise from nonliving matter Idea lasted almost 2000 yearsIdea lasted almost 2000 years

15

16 Examples of Spontaneous Generation

17 Example #1 Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier timesObservation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times

18 Example #1 Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs

19 Example #2 Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.

20 Example #2 It was obvious to them that the mice came from the moldy grain. Conclusion: It was obvious to them that the mice came from the moldy grain.

21 Example #3 Observation: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them.Observation: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them.

22 Example #3 Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies. Conclusion: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies.

23 Abiogenesis Recipes Recipe for mice:Recipe for mice: Place a dirty shirt or some rags in an open pot or barrel containing a few grains of wheat or some wheat bran, and in 21 days, mice will appear. There will be adult males and females present, and they will be capable of mating and reproducing more mice.

24 Disproving Spontaneous Generation

25 Francesco Redi

26 Step 1 - Observation There were flies around meat carcasses at the Butcher shop.There were flies around meat carcasses at the Butcher shop. Where do the flies come from?Where do the flies come from? Does rotting meat turn into or produce rotting flies?Does rotting meat turn into or produce rotting flies?

27 Step 2 - Hypothesis Rotten meat does not turn into flies. Only flies can make more flies.Rotten meat does not turn into flies. Only flies can make more flies.

28 Redi’s ( ) Experiments What is the the manipulated variable?

29 Redi’s ( ) Experiments What is the the manipulated variable?

30 Redi’s ( ) Experiments What is the responding (dependent) variable? 1. Unsealed – maggots on meat 2. Sealed – no maggots on meat 3. Gauze – few maggots on gauze, none on meat Name several controlled variables:

31 Disproving Spontaneous Generation of Microbes

Observations Hypothesis Experiment Cycle repeats many times. By you and by others The hypothesis gets more and more certain. Becomes a theory A thoroughly tested model that explains why things behave a certain way.

Theory can never be proven. The best explanation Useful because it predicts behavior Helps us form mental pictures of processes (models) Observations Hypothesis Experiment

Another outcome is that certain behavior is repeated many times Scientific Law is developed Description of how things behave Usually an equation Law - how Theory- why Observations Hypothesis Experiment

Prediction Experiment Modify Observations Hypothesis Experiment Law Theory (Model)

Communication Use Journals –Do research –Write article Describe procedures, methods, and findings –Submit for peer review Sent back for editing –Publish Letters to editor respond.

Collaboration Working together Teams –Different skills –Different specialties Internet and Conferences

Chemistry Warm Up 1. How does a hypothesis become a theory? 2. Are theories ever wrong? 3. If a scientist subscribes to a hypothesis, but performs an experiment that disproves the hypothesis what should he or she do? 4. Explain the role of collaboration and communication in the scientific method. 5. What is a. manipulated variable? b. responding variable? c. controlled variable? Grading for this warm up: I didn’t understand, so I put my name and the date on the paper, and wrote down the questions – 1 point I wrote complete and correct answers to at least half of the questions – 2 more points (total of 3 points) I wrote complete and correct answers to all of the questions 2 more points (total of 5 points) When you finish, read and take notes 1.4 and andswer 26 and 27 in that chapter.

Problem Solving Only way to get good is to practice Two parts –Developing Plan- Hard part Higher level thinking –Implementing Plan- Not so hard Application level

Solving Numeric Problems Three steps- 1.Analyze Known –Numbers –Measurements –Equations Unknown –What are you looking for? –What units?

Solving Numeric Problems Three steps- 1.Analyze Plan –The heart of problem solving –Diagram –Look info »Table »Graph »Equation

Solving Numeric Problems Three steps- 1.Analyze 2.Calculate Easiest part Convert measurements Rearrange Appendix C

Solving Numeric Problems Three steps- 1.Analyze 2.Calculate 3.Evaluate Reasonable? Read the question, did you answer it? Check your work Estimate

Practice What is the length, in centimeters, of a inch ruler, given that there are 2.54 centimeters per inch?

Practice A certain ball when dropped from any height, bounces one-half the original height. If the ball was dropped from a height of 60 in. and allowed to bounce freely, what is the total distance the ball has traveled when it hits the ground for the third time? Assume the ball bounces straight up and down.

Conceptual Problems Without numbers or math Two steps 1.Analyze Identify known and unknown Plan 2.Solve

Practice You find a sealed box with strings protruding from three holes, as shown in the diagram. When you tug string A, it becomes longer and string C becomes shorter. When you tug string B, it becomes longer, but strings A and C are not affected. Make a diagram showing the arrangement of the strings inside the box.