Chapters 1 & 2

1. Chapters 1 & 2 Matter, Density & Specific Gravity, Significant Figures et.al., Chemical History

2. What is Chemistry?What does it have to do with me?

3. What Does It Have To Do With Me? “What does chemistry have to do with me?” said Mr. Averageman, as he looked at a page printed with ink made by a chemical process, and tied his shoes, made of leather tanned by a chemical process. He glanced through a pane of glass, made by a chemical process, and saw a bakers wagon full of bread leavened by a chemical process, and a draper’s wagon delivering a parcel of silk, dyed by a chemical process. He put on a hat, shaped by a chemical process, and stepped out on the asphalt pavement, compounded by a chemical process, bought a daily paper with a pennyrefined by a chemical process. “No,” he added, “of course not, chemistry has nothing to do with me.” Herbert Newton Casson 1869-1964 [Merrill Chemistry 1995

4. This is a liquid crystal molecule.

5. These are liquid crystal fibers.

6. Ever use any of these?

7. What is Chemistry and How Did We Get to This Point? Chemistry is called the ‘central science’. Studies the structure and properties and changes of matter.

9. Scientific Method

10. What is Matter? • Complete ‘Is It Matter?’ probe individually. (5) • When instructed, share your answers and your reasoning w/ a partner (5)

11. Matter - the ‘stuff’ that everything is made of • Takes up space • Has mass • Has inertia • Has energy

12. Three dimensional Takes up space means that it is

13. the quantity of matter present Gram units Has mass indicates

14. Has inertia refers to • the tendency of a body to maintain its state of rest or uniform motion unless acted upon by an external force inertia

15. Has energy which means • The ability to do work • In science we say that work is done on an object when you transfer energy to that object.

16. Mass and Inertia Relationship?

17. Watch the demo!

18. What did you notice about… • Their hands? • Which was more difficult to catch? • Which required greater effort to stop ? • Remember that inertia is the resistance to a change in motion.

19. What can you conclude about the relationship between mass and inertia? • More mass = More inertia

20. Mass and Energy Relationship?

21. Assignment • Read “Nature of Energy” • p 516 - 518 in text

22. Many different types of energy • Chemical • Nuclear • Radiant • Heat • Light • Electrical • Mechanical • Kinetic • Potential

23. One form of energy can be transformed into another. chemical potential radiant electrical kinetic

24. Significant Figures, Calculations and Measurements

25. SI system of units • modern metric • Be able to recognize the order of the prefixes. • Be able to convert from one unit to another.

26. kL hL dkL dL cL mL

27. Kids have days they don’t care much. kilo hecto deka meter deci centi milli liter gram To change 11.263 cg to deka grams… To change 1.235 km to millimeters …

29. Significant Figures

30. Atlantic/Pacific Rule • To determine the number of sig figs in a given value, use the Atlantic/Pacific Rule regarding decimals Pacific Ocean Atlantic Ocean

31. Significant Figures (con’t) • If the decimal is Absent, count from the Atlantic side from the first non-zero digit • If the decimal is Present, count from the Pacific side from the first non-zero digit • Do NOT stop counting until you’ve run out of digits! • A bar above a zero indicates the marked zero was the estimated value in the measurement and is to be included in calculating the accuracy of the instrument and in determining the number of significant figures.

32. How many sig figs are in each number? • 408.00 g  • 639.0 g  • 0.0058020 mm  • 5640 m  • 0.002 g  • 3,090, 000 km  5 sig figs 4 sig figs 5 sig figs 3 sig figs 1 sig fig 3 sig figs

33. Ice Cubes in a Bag - probe • Complete ‘Ice Cubes in a Bag’ probe individually. (5) • When instructed, share your answers and your reasoning w/ a partner (5)

34. “Matter and energy are two sides of the same physical entity.” Albert Einstein • E = mc2 • E = Energy • m = Mass • c = speed of light • 3 x 108m/s

35. Law of Conservation of Mass and Energy • matter and energy are interchangeable • the total amount of matter and energy in the universe is constant

36. Because of this, chemical rxn… • are always accompanied by changes in energy (E) • E given off - exothermic • E used – endothermic • Cannot gain or lose • mass of reactants = mass of products

37. A thought experiment… • You have just made lemonade. You taste it and find that you pucker when you drink it. • What should you do to ‘fix’ the lemonade?

38. “Add sugar” ... qualitative solution • “Add 1 cup of sugar” ... quantitative solution • *has Numeral • *has UNIT

39. Mass v. Weight • Mass – amount of matter present • Weight – measure of the pull of gravity on the mass. 80 kg

40. Mass v. Weight • The gravitational force on the moon is 1/6th that of the earth. • weight is less on the moon. 13.3 kg 13.3 kg

41. Basic unit • original measurement

42. Derived unit • - result of a mathematical function performed on basic units • volume of a box [l x w x h], • speed [distance/time]

43. Measuring!

44. Measuring • Compares a feature of an object to a standard • For example: • the length of a book is compared to the standard length of a ruler • the mass of a jar of pickles is compared to the standard mass of a gram • Measurement tools we will often use in the lab: • Balance (measures mass) • Graduated cylinder (measures volume) • Meter stick (measures length)

45. When reading an instrument… • Consider all forms of error that could occur • Human error (we all make mistakes) • Equipment error • Changing environmental conditions • Ex: Pressure • No instrument is 100% accurate

46. All measurements MUST have… • Number value • Unit • Indicator of the degree of accuracy • Significant figures indicate the degree of accuracy • The number of digits in the measurement shows the degree of precision of the measuring instrument, which shows how accurate the measurement is

47. When taking a measurement, remember: • Read all numbers from the instrument PLUS one additional ESTIMATE • When reading a measurement from a digital readout, treat the last number on a digital readout as an estimate

48. Significant Figures • All of the numbers that can be directly read from an instrument PLUS one additional estimated number • For digital instruments such as the electronic balance, the last digit IS the mechanically estimated value • Significant figures reflect the precision of an instrument, which shows the accuracy of a measurement

49. Accuracy • Nearness to an accepted value • Measured in ERROR • ABSOLUTE ERROR EA = O – A • EA – absolute error • O – observed; may be individual or experimental average • A – accepted value • RELATIVE ERROR (Percent Error) ER = (EA A)  100 or Percent error = experimental value – accepted value X 100 accepted value

50. Precision • Repeatability; consistency; closeness of multiple measurements to each other • Measured in DEVIATION • ABSOLUTE DEVIATION DA = OI - M • OI – individual observed trial • M – average of all trials • RELATIVE DEVIATION DR = (DA M)  100