Chapter 2: Energy and Matter

1. Chapter 2: Energy and Matter 2-1 Energy 2-2 Temperature 2-3 Matter 2-4 Elements and Compounds 2-5 Mixtures

2. Name 3 basic forms of nrg State the law of conservation of nrg 2-1 Energy

3. Need for nrg • Heat water for cooking, bathing, etc. • Provide nourishment for our bodies • Travel long distances in comfort

4. nrg • The capacity to do work or to produce heat • Work is the ability to move an object over a distance against a resisting force • A locomotive moves a train against the resisting force of the air and friction of the wheels • Sunlight striking solar panels to power a motor against the resistance of the attached appliance • A chocolate bar gives you nrg to climb a steep hill against the resisting force of gravity

5. Forms of nrg • nrg can be grouped under 3 headings • Radiant nrg: light nrg • sunlight • Kinetic nrg: nrg of motion • Locomotive down the tracks • Mechanical nrg – moving parts of a machine • Thermal nrg – random internal motion of particles w/in matter • Potential nrg: stored nrg because of position/ arrangement of particles • Stored rain water wheel

6. Measuring nrg • calorie (cal): measures the amount of heat needed to raise the temp of 1g of water 1˚C • 1 cal = 1g x 1˚C • How many calories of heat would be needed to raise 5g of water 1˚C ? • 5g x 1˚C = 5 cal • Calorie (Cal): measures the nrg stored in food • 1 Cal = 1000 cal or 1 kilocalories • Chocolate bar w/ 200 Cal = 200 kcal = 200 000 cal • Joule (J): SI unit of nrg • Lifting 1 apple the length of 1 meter = 1 joule • 1 cal = 4.184 J

7. Sample problem • A student uses 30. J of nrg putting books on a shelf in the classroom. Convert this amount of nrg from joules to calories. 30. J 1 cal 4.184 J = 7.2 cal

8. Law of Conservation of nrg • In any process, nrg can not be created or destroyed • Process: any situation where nrg is converted • Examples: • Hitting a baseball transfers kinetic nrg of the bat to the ball • Striking a match transforms chemical nrg into heat and light

9. The nrg crisis • If nrg is never created or destroyed, how can we be running out of nrg? • The nrg gets turned in to another form of nrg

10. 2-1 section review • Page 60 (1-5)

11. Compare the Fahrenheit, Celsius, and Kelvin temperature scales Explain what is meant by absolute zero 2-2 Temperature

12. Why can’t we use touch to measure temperature? • There are nerves on our skin that are sensitive to temp • Some people are more sensitive than others • A room that feels comfy to 1 person, may feel cold to another • Must use a more precise method • Thermometer – accurate and precise • Galileo Galilei (1564-1642) doctor who invented the 1st thermometer to measure the fevers in his patients.

13. Parts of a thermometer Stem Filled w/ colored alcohol As thermometer is heated, the liquid expands and rises As thermometer is cooled, the liquid contracts and falls Bulb

14. Comparison of Celsius and Fahrenheit

15. Kelvin temperature scale • Unit = kelvin (K) • No degree symbol (˚) is used • A temperature change of 1 kelvin is the same as a change of 1 Celsius degree • Kelvin has absolute zero • The point at which all motion of particles ceases • All kinetic nrg stops • Absolute zero = -273.15˚C • ˚C = K – 273 • K = ˚C + 273

16. Example • Temps close to absolute zero are incredibly cold, at 50. K air will freeze into a solid! Convert 50. K to the Celsius scale. • ˚C = K – 273˚C = 50. – 273˚C = -223 ˚C

17. Practice • Normal body temp is 310 K. Convert to ˚C • 37˚C • Antifreeze, or ethylene glycol, boils at 197˚C. Convert this to kelvin. • 470 K

18. Pursuing absolute zero • Read w/ your partner the Connection on page 64 • Answer this questions when you are done reading • Why would it be good for scientists to reach Absolute Zero?

19. Name and describe the 4 states of matter Compare physical and chemical properties of matter State the law of conservation of mass 2-3 Matter

21. Matter • Matter is anything that has mass and volume • Anything that takes up space

22. States of matter • 4 states: • Solid • Holds a particular shape, has definite volume • Molecules are rigid and structured • Liquid • Does not hold shape but does have definite volume • Molecules are disordered • Gas • No definite shape or volume • It expands to fill the shape of the container • Molecules in constant motion • Plasma • Inside stars

24. Short explanation of the matter and the 4 states of matter Video

25. Properties of matter • When you were at lunch today, how did you find your friends to eat with? • What did you do to find them?

26. Physical properties • Characteristics of a substance you can observe w/o changing it • Examples: • Density • Color • Mass • Texture • Most anything you find through using your senses

27. Chemical properties • Characteristics of a substance that cannot be observed w/o changing it • Examples: • Flammability – tendency to burn in air • If it is a property that will change the substance to be something else and is unreturnable, it is a chemical property

28. Changes in matter • Physical changes • Do not alter the identity of the substance • If I tear a piece of paper into 2, 3, or even 20 pieces, it is still paper • Chemical changes/Chemical reactions • Do alter the identity of the substance • If I set those pieces of paper on fire, they would no longer be paper

30. Difference b/w chemical property and chemical change • A property is describing what could happen • A change is describing what is or what already happened • Which is the property, which the change? • Leaves change colors in the Fall • When I looked out my window this morning, I noticed the leaves are starting to change color.

31. Identify whether the underlined phrases are chemical or physical change or neither Sample problems

32. Problem #1 Dear Aunt Linda, Prom night was great fun! Tony, my date, looked very handsome in his rented tux – it was a shame the dog tore that little hole in his trousers. First we went to dinner at Chez Chemie. I was a little surprised that we had to light the candle on our own table and put ice water in the glasses, but the restaurant was vey busy and we didn’t mind. (The ice melted right away, too, and we had to add more.)

33. Problem #2 We both ordered shrimp Creole. While we waited, we cut slices from a loaf of warm French bread – yum! My shrimp Creole was delicious. But poor Tony! The waiter was hurrying so much he spilled the whole plate on him. Tony was sweet about it, though. We got him cleaned up pretty well. He ordered a hamburger after that. He also ordered a baked potato, but he had to send it back to be cooked some more because it was still hard. It came back looking rather block, but Tony said it tasted fine.

34. Problem #3 Thank goodness it was a warm evening. We had to drive with the windows rolled down because Tony was starting to smell like a fish market. At the prom, we actually danced in the moonlight! (We couldn’t dance indoors on account of you know who.) We had a wonderful time. It really wasn’t anyone’s fault that Tony caught the edge of his sleeve on fire reaching over the snack table – I think too many little candles were burning on it. Mrs. Donaldson was mad that Tony dunked his arm in the punch bowl to put the fire out, but honestly what else could he do? He tipped over a vase of flowers to get to the punch bowl in time, and it shattered into a thousand pieces. Everyone stopped and stared, but no one got hurt. On the way home, we happened to pass the tuxedo rental store, and I saw a “Help Wanted” sign. That was lucky, said Tony – he was going to need a job to pay for what happened to his suit! Love, Janice P.S. Tony loves his new job, and just been promotes to assistant manager!

35. Conservation of Matter • Matter can never be created or destroyed • Means the molecule that were here at the beginning of time are still here • Law of conservation of matter in effect for the universe

36. Antoine Lavoisier (1743 – 1794) • Uncovered the law of conservation of matter • Known for his accurate and precise measurements • The balance was his most treasured tool • Worked with his wife • Killed at the guillotine after the French Revolution b/c he was a part of a group who collected taxes for the gov’t

37. Explain the difference b/w an element and compound 2-4 Elements and Compounds

38. Elements • A substance that cannot be separated into simpler substances by a chemical change • A little over 100 elements known today • Named after the scientist, country, state, or even planets • einsteinium, americium, californium, plutonium • Use element symbols to abbreviate names • 1st letter always capital while 2nd, if there is one, will be lowercase • Al for aluminum, H for hydrogen, He for helium • Use the periodic table to organize the elements

39. Compounds • 2+ elements combine in a chemical reaction • In fixed proportions • When magnesium is burned in air, it reacts with the oxygen in the air to produce magnesium oxide + air 

40. Compare heterogeneous and homogeneous mixtures Describe several techniques to separate mixtures 2-5 Mixtures

41. Mixtures • A combination of 2 or more pure substances in which each pure substance keeps its individual chemical properties • This means you can separate them after you mix them • It’s not a permanent change • Most substances want to mix, it is hard to find and keep a substance pure

42. Examples of Mixtures • Sand + Water • How could we separate these? • Table salt + Water • How could we separate these?

43. Compound vs Mixture • Compounds • Same composition • 2 hydrogen and 1 oxygen always make water • Mixtures • Varied composition • Collection of elements and compounds

44. Pure Substances • Can be elements or compounds • How do you decide which? • Electrolysis – an electric current is passed through a sample • If the sample is an element, nothing will happen • If the sample is a compound, it will separate into the elements that make it up. • Same composition • Always has the same physical and chemical properties • Mixtures can be separated into pure substances

45. Types of mixtures

46. Homogeneous Mixtures • Mixture that is the same throughout • Also called a solution • Examples • Sport drinks • Salt water • Air you breath • Brass (copper + zinc)

47. Heterogeneous Mixture • Mixture that has different properties in different regions • Examples • Sand and water • Cereal • Pizza • Chocolate Chip Cookies

48. How do we separate mixtures? • Distillation • Filtration • Chromatography

49. Distillation • Used to separate 2 liquids • Based on boiling points of each liquid

50. Filtration • Used to separate a solid from a liquid