2. WHAT IS CHEMISTRY ? Demo: Let’s make slime! Chemistry – the study of matter and its reactions and its reactions Matter - anything that has mass and volume mass and volume - Includes living and - Includes living and non-living things non-living things

3. AREAS OF STUDY

4. Organic Chemistry – C compounds Inorganic Chemistry – non-C compounds Biochemistry – study of living matter Analytical Chem. – composition of matter Physical Chem. – mechanisms, rate and energy transfer

5. THINKING LIKE A SCIENTIST The Scientific Method 1. Analyze - identify the known - find the unknown - find the unknown 2. Calculate - make conversions - solve for the unknown - solve for the unknown 3. Evaluate - does the answer make sense Theory – a well tested explanation for a set of observations Law – concise statement that summarizes a set of results

6. MATHEMATICAL CALCULATIONS I Scientific Notation (Exponential form) – used to express very large and very small numbers coefficient X 10 to a power coefficient X 10 to a power ↓ ↓ ↓ ↓ > 1 1 < 10 the # of times the coefficient is multiplied by 10 to equal the standard number Standard FormExponential Form Standard FormExponential Form 25,000 = 2.5 x 10 4 25,000 = 2.5 x 10 4

7. DETERMINING EXPONENTIAL FORM For Numbers > 10 Exponent = the number of times the decimal point is moved to the left to produce a coefficient between 1 and 10 Exponent = the number of times the decimal point is moved to the left to produce a coefficient between 1 and 10 Ex. 8,200,000 6 places = 8.2 x 10 6, or, 8.2 is multiplied by 10 - 6 times to equal 8,200,000 6 places = 8.2 x 10 6, or, 8.2 is multiplied by 10 - 6 times to equal 8,200,000 2,250 = 2,250 =

8. For numbers < 1 The exponent is negative * Indicates the number of times the coefficient is divided by 10 to get to the standard To convert from the standard – count the number of times the decimal must be moved to get to the coefficient Ex. 0.00075 = 4 places = 7.5 x 10 -4 or, 7.5 divided by 10, 4 times 4 places = 7.5 x 10 -4 or, 7.5 divided by 10, 4 times

9. CONVERTING FROM SCIENTIFIC NOTATION TO STANDARD FORM 1. For + exponents → move the decimal to the right 2. For (–) exponents → move the decimal point to the left Ex. 3.3 x 10 -6 = ______________ Ex. 3.3 x 10 -6 = ______________ 1.5 x 10 3 = ______________ 1.5 x 10 3 = ______________

10. MULTIPLYING AND DIVIDING Multiplying 1. Multiply the coefficients 2. ADD the exponents 3. Re-configure if necessary Ex. (2 x 10 2 ) x (4 x 10 6 ) = ___________ Ex. (2 x 10 2 ) x (4 x 10 6 ) = ___________ (3.1 x 10 4 ) x (5 x 10 -7 ) = ___________ (3.1 x 10 4 ) x (5 x 10 -7 ) = ___________

11. Dividing 1. DIVIDE the coefficients 2. SUBTRACT the exponents 3. Re-configure if necessary Ex. 3.0 x 10 5 = ______________ Ex. 3.0 x 10 5 = ______________ 6.0 x 10 2 6.0 x 10 2 3.0 x 10 5 = ______________ 3.0 x 10 5 = ______________ 6.0 x 10 -3 6.0 x 10 -3

12. ADDING AND SUBTRACTING 1. Both exponents MUST be the same 2. Convert one number if necessary 3. Add (or subtract) the coefficients 4. Re-configure if necessary Ex. 8.0 x 10 2 + 5.4 x 10 3 = 8.0 x 10 2 + 54 x 10 2 = _____________ 8.0 x 10 2 + 54 x 10 2 = _____________

13. II SIGNIFICANT FIGURES Those digits (of a measurement) known with certainty plus the right most digit that is estimated. Those digits (of a measurement) known with certainty plus the right most digit that is estimated.Ex.

14. Counting Sig Figs 1. Every non-zero digit is significant 2. Zeros in the middle of a # are significant ex. 605 = 3 sig figs ex. 605 = 3 sig figs 3. Zeros at the beginning of a number are NOT significant = placeholders ex..0025 = 2 sig figs ex..0025 = 2 sig figs 4. Zeros at the end of a number are only significant if they follow a decimal ex. 7500 = 2 sig figs ex. 7500 = 2 sig figs ex. 75.00 = 4 sig figs ex. 75.00 = 4 sig figs 5. Counted numbers = unlimited sig figs

15. The Atlantic and Pacific Rule Does the number have a decimal point? (Easy way to count sig figs) Decimal point Absent - Atlantic Ocean Decimal point Present - Pacific Ocean

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17. Decimal point present: Start counting with first non-zero digit and count until the end of the number Start counting with first non-zero digit and count until the end of the number 2545.300 g 0.004530 km has 7 7 sig figs has 4 4 sig figs Start on Pacific (left) side of number

18. Decimal point absent: Start on Atlantic (right) side of number Start on Atlantic (right) side of number non-zeroStart counting with first non-zero digit and count until the end of the number 5400 m has 2 2 sig figs 5431 m has 4 4 sig figs

19. Calculations with sig figs Multiplication and Division significant figures least number The answer can have only as many significant figures as the number with the least number of sig figs Calculations are Rounded Off

20. 24.56 cm X 14 cm = a) 343.84 cm 2 b) 343.8 cm 2 c) 343 cm 2 d) 340 cm 2

21. EXAMPLE 2.2 X 10 4 X 3.12 X 10 6 2.2 X 10 4 X 3.12 X 10 6 Answer = 6.9 x 10 10 Answer = 6.9 x 10 10

22. Addition and Subtraction decimal places least number The answer can have only as many decimal places as the number with the least number of decimal places Calculations are Rounded Off

23. 422.63 cm 29.472 cm 115.9 cm ________________ + a) 568.002 cm b) 568.00 cm c) 568.0 cm d) 568 cm

24. MEASUREMENTS Accuracy – a measure of how close a measurement comes to the true value of whatever is being measured To evaluate – compare the measured value to the true value Precision – a measure of how close a series of measurements are to one another To evaluate – compare the values of 2 or more repeated measurements

25. ACCURACY AND PRECISION

26. III CALCULATING ERROR Error – difference between the accepted value and the experimental value may be + (greater) or – (less) may be + (greater) or – (less) Calculated by % = Percent Error % Error = Exp Value – Accepted Value x 100 Accepted Value Accepted Value

27. EXAMPLE A student measured a sample of NaCl to be 22.75 grams. The true value of the sample was 22.50 grams. Calculate the % error A student measured a sample of NaCl to be 22.75 grams. The true value of the sample was 22.50 grams. Calculate the % error Known: Measured sample = 22.75 g Known: Measured sample = 22.75 g True mass = 22.50 g True mass = 22.50 g Unknown: % error Unknown: % error Solve: 22.75 g – 22.50 g x 100 = 22.50 g 22.50 g 0.25 x 100 = 1.1 % 0.25 x 100 = 1.1 % 22.50 22.50

28. HW – PG 72 #’s 13-15 13. Measured value = 124.1 o C Actual value = 125.7 o C Actual value = 125.7 o C Unknown = % Error Unknown = % ErrorSolve 124.1 o C – 125.7 o C x 100 = - 1.6 o C = 125.7 o C 125.7 o C 125.7 o C 125.7 o C 0.0127287 x 100 = 1.272 %

29. 14. 11 soccer players 10, 800 m 10, 800 m 0.070020 m note: counted items 0.070020 m note: counted items 5.00 m 3 have unlimited sig figs 5.00 m 3 have unlimited sig figs15. a) (5.3 x 10 4 ) + (1.3 x 10 4 ) = 6.6 x 10 4 b) (7.2 x 10 -4 ) / (1.8 x 10 3 ) = 4.0 x 10 -7

30. c. 10 4 x 10 -3 x 10 6 = 10 7 d. (9.12 x 10 -1 ) – (4.7 x 10 -2 ) = (9.12 x 10 -1 ) – (.47 x 1 0-1 ) = 8.7 x 10 -1 (9.12 x 10 -1 ) – (.47 x 1 0-1 ) = 8.7 x 10 -1 e. (5.4 x 10 4 ) x (3.5 x 10 9 ) = 18.9 x 10 13 = 1.89 x 10 14 = 1.9 x 10 14 1.89 x 10 14 = 1.9 x 10 14

31. created International System of Units 1790 – French Academy of Sciences created the metric system Based on 3 Requirements

32. Basic Standard = Earth 1. The unit of length was to be a portion of the Earth's circumference

33. Internal Consistency 2. Units for capacity (volume or space) and mass related to the unit of length

34. Ease of Use - Calculations 3. Larger and smaller units are created by multiplying or dividing the basic units by factors of 10

35. Smaller & Larger Units ► 1/10 of a meter = decimeter ► 1/100 of a meter = centimeter ► 1/1000 of a meter = millimeter ► 10 meters = dekameter ► 100 meters = hectometer ► 1000 meters = kilometer

36. Prototype kilogram in France

37. Systeme International (SI) ► Based on the metric system, invented in 1790*  Originally, earth-based standards  Volume & mass linked to length  Larger & smaller multiples of each unit related by powers of 10 *updated in 1960

38. What is a meter? 1790: 1/10,000,000 th of the distance from the North pole to the equator / 1983: the distance light travels in a vacuum in 1/299,792,458 th of a second

39. What is a Liter? defined as a cube measuring 10 centimeters on each side, or 1000 cm 3 based on the meter, which is based on the Earth 10 cm

40. What is a kilogram? 10 cm mass of 1 Liter of water at 4°C Why water? So… the kilogram is based on the liter, which is really based on the meter, which is really based on the Earth

41. What is a second? The second was originally defined as 1/86,400th of the average solar day Now: defined in terms of electron transitions in Cs-133

42. AbbreviationNameQuantity mmeterLength kgkilogramMass KkelvinTemperature ssecondTime cdcandela Luminous Intensity Aampere Electric Current molMole Amount of Substance 7 Fundamental Quantities of SI

43. Derived Units ► Combinations of fundamental units ► Many, many derived units ► Examples:  Speed or distance/time = m/sec  Area or Length X Width = cm 2  Volume or Length X Width X Height = cm 3  Density or Mass / Volume = g/ml

44. What is a kelvin? The kelvin is defined in terms of water & absolute zero 0 K = Absolute zero bp of H 2 O = 100  C = 373 K mp of H 2 O = 0  C = 273 K

45. What is a mole? ► The amount of substance which has as many elementary particles as there are atoms in 0.012 kilogram (12 grams) of carbon-12

46. METRIC MEASUREMENTS MEASUREMENT DEFINITION STANDARD UNIT 1. Length 2. Mass 3. Volume 4. Temperature 5. Time

47. UsePowerValueSymbolPrefix Gigabyte 10 9 1,000,000,000 GGiga Megamillion 10 6 1,000,000MMega kilometer 10 3 1,000kKilo decimeter 10 -1 0.1ddeci centimeter 10 -2 0.01ccenti millimeter 10 -3 0.001mmilli micrometer 10 -6 0.000001  micro nanometer 10 -9 0.000000001nnano Prefixes in the SI System

48. Prefixes ► The prefixes can be used with all 7 fundamental units!  Kilometer  Milliliter  Centigram  Microsecond  Nanokelvin

49. IV METRIC CONVERSIONS 1. Temperature Conversions K = o C + 273 K = o C + 273 o C = K – 273 o C = K – 273 ex. BP of H 2 O is 100 o C ex. BP of H 2 O is 100 o C BP of H 2 O in K = BP of H 2 O in K = ex. FP of H 2 O = - 273 o K ex. FP of H 2 O = - 273 o K FP of H 2 O in o C = FP of H 2 O in o C =

50. CONVERSIONS CONVERSIONS 2. Metric Conversions – used to measure quantities in different ways Ex. 1 meter = 10 decimeters = 100 cm = 1000 mm Ex. 1 meter = 10 decimeters = 100 cm = 1000 mm Conversion Factor – a ratio of equivalent measurements - used to change one unit to another unit - used to change one unit to another unit - the value of the numeral will change (in multiples of 10) - the value of the numeral will change (in multiples of 10) - actual size and quantity stays the same - actual size and quantity stays the same ex. 1 m = conversion factor = 100 cm 100 cm 1 m 100 cm 1 m

51. Conversion Factors Write the conversion factors for the following: l to ml = l to ml = Kg to g = cm to mm = l to μl =

52. Conversion Problems ► Convert 3.5 kg to g ► Known: 1000 g = 1 kg ► Unknown: # g ► Calculate ► 3.5 kg x 1000 g = 3,500 g ► 1 kg ► Note: conversion factor must be written to cancel all units except the unknown unit.

53. V EQUATIONS Density = Mass / Volume How would you find mass if you are given the density and the volume? How would you find mass if you are given the density and the volume? Solve for M M = D x V Solve for V V = M/D

54. TO MODIFY AN EQUATION Change Sides……..Change Signs D = M D = M V V = MM = VD D

55. EXAMPLE P 1 x V 1 = P 2 x V 2 P 1 x V 1 = P 2 x V 2 SOLVE FOR P 2 P 2 = P 1 x V 1 P 2 = P 1 x V 1 V 2 V 2

56. CALCULATIONS WITH UNITS Density = g/cm 3 Mass = g Volume = cm 3 Mass = Density x volume Mass = Density x volume g = g x cm 3 g = g x cm 3 cm 3 cm 3

57. CALCULATIONS WITH UNITS P 2 = P 1 x V 1 P in atm V 2 V in ml V 2 V in ml atm = atm x ml atm = atm x ml ml ml