1. Unit 2: Matter and Energy Chemistry

2. Matter Introductory Definitions matter: anything having mass and volume mass: weight: volume: units: L, dm 3, mL, cm 3 L3L3 state of matter: the amount of matter in an object the pull of gravity on an object the space an object occupies solid, liquid, or gas

3. composition: copper: water: properties: -- atom: a basic building block of matter what the matter is made of many Cu atoms many groups of 2 H’s and 1 O describe the matter what it looks like, smells like; its mass, temp., etc. how it behaves ~100 + diff. kinds

4. Elements  contain only one type of atom 1. monatomic elements consist of unbonded, “like” atoms e.g., 2. polyatomic elements consist of several “like” atoms bonded together diatomic elements: others: Fe, Al, Cu, He H 2 O 2 Br 2 F 2 I 2 N 2 Cl 2 P 4 S 8 “7 7 7”

6. allotropes: different forms of the same element in the same state of matter OXYGEN CARBON oxygen gas ozone elemental carbon graphite diamond buckyball (O 2 ) (O 3 )

7. molecule: a neutral group of bonded atoms Description Chemical Symbol Model 1 oxygen atom 1 oxygen molecule 2 unbonded oxygen atoms 1 phosphorus atom 1 phosphorus molecule 4 unbonded phosphorus atoms O O 2 2 O P P 4 Elements may consist of either molecules or unbonded atoms. 4 P

8.  Compounds …contain two or more different types of atoms …have properties that are different from those of their constituent elements Na (sodium): Cl 2 (chlorine): explodes in water poisonous gas table salt (NaCl)

9. Atoms can only be altered by _______ means. Molecules can be altered by ________ means. (i.e., chemical reactions, chemical changes) nuclear chemical e.g., Dehydration of sugar C 12 H 22 O 11 (s)  12 C(s) + 11 H 2 O(g) Electrolysis of water 2 H 2 O(l)  2 H 2 (g) + O 2 (g) Atomic blast at Hiroshima U Ba Kr neutron “bullet”

10. Every sample of NaCl tastes the same, melts at the same temp., and is 39.3% Na and 60.7% Cl by mass. Compound Composition All samples of a given compound have the same composition.

11. Phosgene gas (COCl 2 ) is 12.1% carbon, 16.2% oxygen, and 71.7% chlorine by mass. Find # of g of each element in 254 g of COCl 2. C: O: Cl: 254 g (0.121)= 30.7 g C 254 g (0.162)= 41.1 g O 254 g (0.717) = 182.1 g Cl

12. = 0.828 A sample of butane (C 4 H 10 ) contains 288 g carbon and 60 g hydrogen. Find… A. …total mass of sample B. …% of each element in butane C. …how many g of C and H are in a 24.2 g sample 288 g C + 60 g H 82.8% C, 17.2% H = 348 g % C = = 0.172 % H = C: H: 24.2 g (0.828)= 20.0 g C 24.2 g (0.172)= 4.2 g H

13. A 550 g sample of chromium (III) oxide (Cr 2 O 3 ) has 376 g Cr. How many grams of Cr and O are in a 212 g sample of Cr 2 O 3 ? 68.4% Cr % Cr = and 31.6% O Cr: O: 212 g (0.684)= 145 g Cr 212 g (0.316)= 67 g O chromium (III) oxide

14. Let’s Do a Worksheet! How about “Percentages in Composition”?

15. Classifying Matter (Pure) Substances…have a fixed composition …have fixed properties ELEMENTS COMPOUNDS e.g., Fe, N 2, S 8, UH 2 O, NaCl, HNO 3 Pure substances have a chemical formula. sulfur (S 8 )sodium chloride (NaCl)

16. Mixtures two or more substances mixed together …have varying composition …have varying properties The substances are NOT chemically bonded, and they… retain their individual properties. Tea, orange juice, oceans, and air are mixtures.

17. Two Types of Mixtures 1. homogeneous: (or solution) particles are microscopic; sample has same composition and properties throughout; evenly mixed e.g., Expl. alloy: a homogeneous mixture of metals e.g., Kool Aid bronze (Cu + Sn) brass (Cu + Zn) pewter (Pb + Sn) salt water

18. Two Types of Mixtures (cont.) 2. heterogeneous: different composition and properties in the same sample; unevenly mixed e.g., Expl. suspension: settles over time e.g., tossed salad raisin bran paint snowy-bulb gifts

19. MATTER Chart for Classifying Matter PURE SUBSTANCEMIXTURE ELEMENT COMPOUND HOMOGENEOUS HETEROGENEOUS

20. Let’s Do a Worksheet! How about “Classification of Matter”?

21. Contrast… notice the difference in color 24K GOLD14K GOLD 24/24 atoms are gold element pure gold 14/24 atoms are gold mixture of gold & copper Au homogeneous mixture Au + Cu

22. Now let’s do some calculations. Yay! Math!! In a mixture, we can find out how much of each substance is present. Much like the gold rings This is called percent composition

23. A sample of bronze contains 68 g copper and 7 g tin. A. Find total mass of sample. B. Find % Cu and % Sn. C. How many grams of each element does a 346 g sample of bronze contain? 68 g Cu + 7 g Sn = 75 g 90.7% Cu % Cu = and 9.3% Sn We don’t know. (Bronze is a mixture and isn’t necessarily always 90.7% Cu and 9.3% Sn.) However, assuming these % are correct… Cu:346 g (0.907)= 314 g Cu(and 32 g Sn)

24. Separating Mixtures …involves physical means, or physical changes 1. sorting: 2. filter: by color, shape, texture, etc. particle size is different

25. Separating Mixtures (cont.) 3. magnet: 4. chromatography: one substance must contain iron some substances dissolve more easily than others

26. Separating Mixtures (cont.) 5. density: “sink vs. float” perhaps use a centrifuge decant: to pour off the liquid blood after high- speed centrifuging

27. Separating Mixtures (cont.) 6. distillation: different boiling points heat source thermometer water in (cooler) water out (warmer) more-volatile substance mixture condenser more-volatile substance, now condensed (i.e., the one with the lower boiling point)

28. No chemical reactions are needed to separate mixtures; substances are NOT bonded. dental amalgam

29. Properties of Matter CHEMICAL properties tell how a substance reacts with other substances. PHYSICAL properties can be observed without chemically changing the substance. EXTENSIVE properties depend on the amount of substance present. INTENSIVE properties do not depend on the amount of substance. ONE OF THESE AND ONE OF THESE

30. P, Examples: electrical conductivity……………………… reactivity with water………………………... heat content (total energy)………………… ductile: can be drawn (pulled) into wire….. malleable: can be hammered into shape… brittle…………………………………………. magnetism…………………………………… C, P, I I E P,I P,I P,I P,I

31. Let’s Do a Worksheet! How about “Properties of Matter”?

32. Let’s do a lab on chromotography!

33. Would you like to do a lab? How about the “Casein Glue Lab”?

34. Let’s have a quiz!!

35. States of Matter LIQUIDSOLIDGAS ( ( ) ) vibrating translating; close together translating quickly; far apart

36. Changes in State Energy put into system. Energy removed from system. LIQUIDGASSOLID freezing condensation deposition sublimation boilingmelting

37. Energy  the ability to do work potential energy: kinetic energy: -- e.g., stored energy stored in bonds between atoms in food, energy of motion wiggling, translating, and rotating of particles -- “hot” gas particles move faster, have more KE gasoline, batteries

38. Law of Conservation of Energy: 2 H 2 + O 2  2 H 2 O E after = E before +  + energy + WHOOF!

39. For the combustion of acetylene… PE reactants PE products KE stopper heat, light, sound ENERGY CO 2 + H 2 OC 2 H 2 + O 2 Energy is conserved.

40.  Energy Changes endothermic change: system absorbs heat exothermic change: system releases heat -- Choose “endo” or “exo.” water boiling paper burning steam condensing CO 2 subliming water freezing ice melting beaker feels cold beaker feels hot ENDO EXO EXO ENDO EXO ENDO

41. R P Energy endothermic exothermic R P Energy ACTIVATION ENERGY (most chemical reactions)(photosynthesis) CO 2 + H 2 O + sunlight  C 6 H 12 O 6 + O 2 C + O 2  CO 2

42. Let’s switch gears… The amount of energy that one gets from a chemical reaction will be due in part to the amount of substance available.

43. The Mole Atoms are so small, it is impossible to count them by the dozens, thousands, or even millions. To count atoms, we use the concept of the mole. 1 mole of atoms = That is, 1 mole of atoms = _________ atoms. The mole is the SI unit for “amount of substance.” 602,000,000,000,000,000,000,000 atoms 6.02 x 10 23

44. How Big is a Mole? …about the size of a chipmunk, weighing about 5 oz. (140 g), and having a length of about 7 inches (18 cm). I Meant, “How Big is 6.02 x 10 23 ?” BIG. 6.02 x 10 23 marbles would cover the entire Earth (including the oceans) …to a depth of 2 miles. 6.02 x 10 23 $1 bills stacked face-to-face …and back …7.5 million times. It takes light 9,500 years to travel that far. would stretch from the Sun to Pluto

45. For any element on the Periodic Table, one mole of that element (i.e., 6.02 x 10 23 atoms of that element) has a mass in grams equal to the decimal number on the Table for that element. He 2 4.003 Ne 10 20.180 Ar 18 39.948 Kr 36 83.80 Xe 54 131.29 Rn 86 (222) 1 mole of (i.e., 6.02 x 10 23 ) helium atoms has a mass of 4.0 grams. 1 mol Ne = 20.2 g 1 mol Ar = 39.9 g 1 mol Kr = 83.8 g 1 mol Xe = 131.3 g 1 mol Rn = 222 g

46. It often becomes necessary to use dimensional analysis… You remember… conversion factors! We often need to know the mass if given moles or particles (atoms) To do these conversions, we employ the conversion factors given in the Island Diagram

47. 1 mol = 6.02 x 10 23 particles MOLE (mol) Mass (g) Particle (atoms) 1 mol = molar mass (in g) Island Diagram

48.  Island Diagram Problems 1. How many moles is 3.79 x 10 25 atoms of zinc? = 63.0 mol Zn () 1 mol 6.02 x 10 23 at. 3.79 x 10 25 at. 2. How many atoms is 0.68 moles of zinc? = 4.1 x 10 23 at. Zn () 1 mol 6.02 x 10 23 at. 0.68 mol.

49. 3. How many grams is 5.69 moles of uranium? 5.69 mol () 1 mol 238.0 g = 1,354 g U = 1.35 x 10 3 g U 4. How many grams is 2.65 x 10 23 atoms of neon? () 1 mol = 8.9 g Ne 20.2 g () 1 mol 6.02 x 10 23 at. 2.65 x 10 23 at. 5. How many atoms is 421 g of promethium? 421 g () 1 mol 145 g () 1 mol 6.02 x 10 23 at. = 1.75 x 10 24 at. Pm

50. Let’s Do a Worksheet! How about “Atoms to Mass to Mole”?

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