1. Unit 1 – Measuring Matter and Energy

2. Learning Objectives By the end of this unit, you should be able to: Describe what matter is and apply the law of conservation of mass Make careful qualitative and quantitative measurements of matter using accurate units and vocabulary Calculate the density of an object and determine if it will sink or float

3. Chemistry The study of the structure, properties and composition of matter, and the changes that substances undergo

4. OrganicInorganic Analytical Chemistry Physical Biochemical

5. Matter Anything that has mass and takes up space

6. Mass The amount of matter an object contains

7. Volume The amount of space an object takes up

8. Density The ratio of the mass of an object to its volume

9. Law of Conservation of Matter Matter cannot be created nor destroyed Matter can change

10. Energy Is required for changes in matter Does not have mass or volume

11. The Composition of Air

12. Measuring Matter Quantitative Measurements Use numbers (“quantity”) Considered more objective Qualitative Measurements Use words (“quality”) Considered more subjective Both are valid means of describing matter

13. Classify the following as quantitative or qualitative properties Mass Volume Color Density Texture Smell Length Temperature Phase Quantitative Mass Volume Density Length Temperature Qualitative Color Texture Smell Phase

14. Q: Which of the following is an example of a quantitative measurement? a.“It is really hot in here!” b.“There are too many people in this room!” c.“The temperature is 102 o F!” d.All of the above

15. QUALITATIVE MEASUREMENTS

16. Physical properties Can be observed or measured without changing the substance’s composition Ex: Height, weight, color, phase

17. Chemical properties can only be observed through chemical change Ex: Flammability, reactivity, acidity

18. Physical Changes A physical change alters a substance without changing its composition Can be reversed

19. Chemical changes Require the breaking and forming of bonds between atoms. New substances are formed from the original substances

20. How to tell? Signs of a chemical change: – Color change – Temperature change (colder or warmer) – Release of a gas or solid – Release of light – New/different odors

21. Fancy terms Effervescence is bubbling that occurs as an example of a chemical change A Precipitate is an insoluble solid that forms as a result of a chemical change

22. How is this different from boiling?

23. States of Matter (phases)

24. Properties of States of Matter Physical StateDefinite Shape? Definite Volume? Readily compressible? Solid Yes No LiquidNoYesNo GasNo Yes

25. Plasma: The Fourth State Charged particles in gas-like clouds

26. Yes, a plasma TV is really plasma.

27. So are stars

28. And lightning!

29. Freezing water into ice is an example of… a)A physical change because ice and water are both H 2 O b)A chemical change because a new substance, ice, is formed c)A chemical change because ice is a solid while water is a liquid d)None of the above

30. QUANTITATIVE MEASUREMENTS

31. S.I. Units (Metric System) PropertyUnitsSymbol MassGramsg VolumeLiters*L LengthMetersm TemperatureCelsius/ Kelvin o C, K

32. Prefixes PrefixSymbolNumber value kilok1000 timesGreater than centic100 timesLess than millim1000 timesLess than microμ1 000 000 timesLess than nanon1 000 000 000 timesLess than

33. Unit Metric equivalent Examples Meter1mA little more than a yard Kilometer1,000mAbout 2/3 of a mile centimeter0.01mRadius of a penny millimeter0.001mWidth of a pencil tip liter1L ½ a pop bottle milliliter0.001LAbout 15 drops of water

34. Accuracy and Precision Often mistakenly treated as the same thing Accuracy = how close to accepted value you are Precision = how consistent you are

35. Accuracy vs. Precision

36. Making Accurate & Precise Measurements When recording measurements, estimate 1 place past the known measurement For the example on the right, we know that it is greater than 52 but less than 53. We would record this as 52.8 mL. (+/-.2)

37. Calculating Precision % Error: |Trial Value – Average Value| x 100 Average Value Ex: You make 3 measurements of 20, 22, and 24 mL Avg = 20+22+24 = 22 mL. 3 % error of trial 1 (20 mL) = (20-22)/22 = 9.09%

38. Calculating Accuracy % Error: |Trial Value – Accepted Value| x 100 Accepted Value Ex: You record a measurement as 16g, but the teacher records 20g and is always right. % error = (16-20)/20 = 20%

39. Density The ratio of the mass of an object to its volume D = M / V Density = Mass Volume

40. Practice Mass = 30g Volume = 5cm 3 Density = 6g/cm 3

41. Try again Mass = 6g Volume = 2cm 3 Density = 3g/cm 3

42. Now solve for Mass... Mass = 40g Volume = 4cm 3 Density = 10g/cm 3

43. Now solve for Volume… Mass = 100g Volume = 10cm 3 Density = 10g/cm 3

44. Specific Gravity (relative density) Is a measure of a substance’s density vs. a reference (usually water) Tells you whether a substance will sink or float Any substance will float in a more dense substance than itself Specific gravity of water = 1g/mL

45. Formula Specific Gravity = density of substance density of reference If the SG is less than 1, the object will float If the SG is less than 1, the object will sink

46. Which items will sink in water? Float?

48. Hydrometer is used for measuring specific gravity Used to measure the progress of yeast in wine/beer making Also used to check oil & acid in your car battery

49. Hydrometers are very useful!

50. Predict How could measuring the specific gravity of liquids be useful? If the gravity of a substance changes, what can be inferred?

51. 1 st Law of Thermodynamics: the total energy of a system is constant In other words, energy can be neither created nor destroyed (conservation of energy)

52. Chemistry Cat takes a different approach.

53. 2 nd Law of Thermodynamics: Energy always flows from a high energy object to a low energy object Heat always flows from hot objects to cool objects until they reach equilibrium

54. Temperature Is the degree of hotness or coldness of an object Is a measurement of energy Expressed in Degrees Centigrade (Celsius) or Kelvin

55. The Kelvin Scale is a measurement of the absolute amount of energy in a system Cannot be negative No degrees The Scale was developed by Lord Kelvin, a British noble and scientist

56. Absolute Zero 0K (-273 o C) = Absolute Zero Represents a complete absence of energy Lowest theoretically possible temperature Not naturally occurring; scientists have gotten extremely close

57. Temperature Equivalence oCoC oFoFKelvinDescription -273-459.40Absolute Zero 032273Water freezes 1050283Cool fall day 2068293Room temperature 3086303Normal Summer day 40104313Hot summer day 100212373Water Boils

58. Temperature Conversions K = o C + 273 o C = K – 273 o C = 5/9( o F – 32) o F = 9/5 o C + 32 Ex: 20 o C = 20 + 273 = 293 K 250 K = 250 – 273 = -23 o C 60 o F = 5/9(60-32) = 15.5 o C

59. Practice Problems 1.25 o C = ____K 2.186 o C = ___K 3.-30 o C = ___K 4.100 K = ___ o C 5.300 K = ___ o C 6.456 K = ___ o C 7.58 o F = ____ o C 8.18 o C = ____ o F 298 459 243 -173 27 183 14.4 64.4

60. Extra Practice 1.230 o C = ___K 2.23K = _____ o C 3.-150 o C = ___K 4.120 K = ____ o C 5.513 o C = ____K