Course: General Chemistry I (CHEM 140, Section: 02) Instructor: Cevdet Akbay

1. Course:General Chemistry I (CHEM 140, Section: 02) Instructor:Cevdet Akbay Office location:LS 227 Office phone:672-1943 Office hours:MTWRF 10:00 AM-12:00 PM or by appointments

2. Chemistry:The Study of Change Chapter 1

3. Why ice melts and water evaporates? Why keeping foods cold slows their spoilage? How our bodies use food to maintain life? Why leaves turn colors in the fall? How a battery generates electricity? How Blah blah blah Chemistry supplies answers to these questions and countless others like them. Then, how we define Chemistry? It depends: Chemistry is the study of the properties of materials and the changes that materials undergo. Chemistry is the scientific discipline that treats the composition, properties, and transformations of matter.

4. One of the joys of learning chemistry is seeing how chemical principles operate in all aspects of our lives, from lighting a match to the development of drugs to cure cancer. You are just beginning the journey of learning chemistry. This first chapter provides an overview of what chemistry is about and deals with some fundamental concepts of matter and scientific measurements.

5. Chemistry is the study of matter and the changes it undergoes (another definition) 1. Matter is anything that occupies space and has mass. 2. A substance is a form of matter that has a definite composition and distinct properties. water, ammonia, sucrose, gold, oxygen

6. air, soft drink, milk, solder cement, iron filings in sand A mixture is a combination of two or more substances in which the substances retain their distinct identities. • Homogenous mixture – composition of the mixture is the same throughout. • Heterogeneous mixture – composition is not uniform throughout.

7. magnet distillation Physical means can be used to separate a mixture into its pure components.

8. An element is a substance that cannot be separated into simpler substances by chemicalmeans. • 115 elements have been identified • 83 elements occur naturally on Earth • gold, aluminum, lead, oxygen, carbon • 32 elements have been created by scientists • technetium, americium, seaborgium

9. These elements vary widely in their abundance, as shown in Figure 1.6. Figure 1.6 Elements in percent by mass in (a) Earth's crust (including oceans and atmosphere) and (b) the human body.

10. Some of the more familiar elements are listed in Table 1.2, along with the chemical abbreviations—or chemical symbols—used to denote them. The symbol for each element consists of one or two letters, with the first letter capitalized. These symbols are often derived from the English name for the element, but sometimes they are derived from a foreign name instead (last column in Table 1.2). All the known elements and their symbols are listed on the front inside cover of this text. The table in which the symbol for each element is enclosed in a box is called the periodic table.

11. Water (H2O) Glucose (C6H12O6) Ammonia (NH3) A compound is a substance composed of atoms of two or more elements chemically united in fixed proportions. Compounds can only be separated into their pure components (elements) by chemical means.

12. Most elements can interact with other elements to form compounds. Hydrogen gas, for example, burns in oxygen gas to form water. Figure 1.10

13. Conversely, water can be decomposed into its component elements (hydrogen and oxygen) by passing an electrical current through it, as shown in Figure 1.7. Figure 1.7 Water decomposes into its component elements, hydrogen and oxygen, when a direct electrical current is passed through it. The volume of hydrogen (on the right) is twice the volume of oxygen (on the left).

14. Pure water, regardless of its source, consists of 11% hydrogen and 89% oxygen by mass. This macroscopic composition corresponds to the molecular composition, which consists of two hydrogen atoms combined with one oxygen atom. As seen in Table 1.3, the properties of water bear no resemblance to the properties of its component elements. Hydrogen, oxygen, and water are each unique substances.

15. Law of constant composition: A law that states that the elemental composition of a pure compound is always the same, regardless of its source. This law is also known as law of definite proportions. It was first put forth by the French chemist Joseph Louis Proust in 1800s. Each of the followings can be classified as a heterogeneous mixture, homogeneous mixture, compound, or element. How would you classify each? • 2) Ethyl alcohol • heterogeneous mixture • homogeneous mixture • compound • element • 1) Iced tea • heterogeneous mixture • homogeneous mixture • compound • element • 3) Ozone • compound • homogeneous mixture • heterogeneous mixture • element • 4) Air in the classroom • heterogeneous mixture • homogeneous mixture • compound • element

16. 5) Table salt • heterogeneous mixture • homogeneous mixture • compound • element • 6) A salt and sand mixture • heterogeneous mixture • homogeneous mixture • compound • element 1) b 2) c 3) a 4) b 5) c 6) a • 1) Which of the following is not matter?  • elemental phosphorus • light • dust • pizza • 2) Which of the following is a pure substance?  • concrete • nitrogen • blue-cheese salad dressing • air

17. Which of the following is not a state of matter? • Gas • Vacuum • Solid • Liquid • Passing an electric current through a certain substance produces oxygen and sulfur. This substance cannot be a(n) • Compound • Element • Mixture • Pure substance 1) b 2) b 3) b 4) b

20. Three States of Matter Matter can exist in one of three states of matter: a gas, a liquid, or a solid. A gas is highly compressible and will assume both the shape and the volume of its container. A liquid is not compressible and will assume the shape but not the volume of its container. A solidalso is not compressible, and it has a fixed volume and shape of its own.

21. Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior gas liquid solid assumes the shape and volume of its container particles can move past one another assumes the shape of the part of the container which it occupies particles can move/slide past one another retains a fixed volume and shape rigid - particles locked into place compressible lots of free space between particles not easily compressible little free space between particles not easily compressiblelittle free space between particles flows easily particles can move past one another flows easily particles can move/slide past one another does not flow easily rigid - particles cannot move/slide past one another

22. Properties of Matter Every substance has a unique set of properties (or characteristics) that allow us to recognize it and to distinguish it from other substances. For example, the properties listed in Table 1.3 allow us to distinguish hydrogen, oxygen, and water from one another. The properties of matter can be categorized as physical properties or chemical properties. Physical properties can be measured without changing the identity and composition of the substance. These properties include color, odor, density, melting point, boiling point, and hardness. Chemical properties describe the way a substance may change or react to form other substances. A common chemical property is flammability, the ability of a substance to burn in the presence of oxygen.

23. Some properties—such as temperature, melting point, and density—do not depend on the amount of the sample (matter) being examined. These properties, called intensive properties, are particularly useful in chemistry because many can be used to identify substances. Extensive propertiesof substances depend on the quantity of the sample and include measurements of mass and volume. Extensive properties relate to the amount of substance present.

24. sugar dissolving in water ice melting hydrogen gas burns in oxygen gas to form water Physical or Chemical? A physical change does not alter the composition or identity of a substance. A chemical change alters the composition or identity of the substance(s) involved.

25. Which of the following is a chemical process? • dissolving sugar in water • crushing of stone • tarnishing of silver • melting of lead c • Which of the following is an intensive quantity? • heat content of a substance • mass of a substance • density of a substance • volume of a substance c • Which one of the following is a physical process? • the rusting of iron • the explosion of nitroglycerine • the baking of a potato • the condensation of water vapor • the formation of polyethylene from ethylene d

26. weight = g x mass A 60 kg bar will weigh on earth, g = 9.8 m/s2 ~600 N on earth on moon, g= 1.63 m/s2 ~100 N on moon Matter - anything that occupies space and has mass. • mass – measure of the quantity of matter • SI unit of mass is the kilogram (kg) • 1 kg = 1000 g = 1 x 103 g weight – force that gravity exerts on an object

28. Unit Ex. meter

29. Volume – SI derived unit for volume is cubic meter (m3) 1 cm3 = (1 x 10-2 m)3 = 1 x 10-6 m3 1 dm3 = (1 x 10-1 m)3 = 1 x 10-3 m3 1 L = 1000 mL = 1000 cm3 = 1 dm3 1 mL = 1 cm3

30. mass density = volume A piece of platinum metal with a density of 21.5 g/cm3 has a volume of 4.49 cm3. What is its mass? m m d = d = V V Density – SI derived unit for density is kg/m3 1 g/cm3 = 1 g/mL = 1000 kg/m3 = 21.5 g/cm3 x 4.49 cm3 = 96.5 g m = d x V

31. K = 0C + 273.15 0F = x 0C + 32 9 5 5 9 0C = x (0F – 32) 273 K = 0 0C 373 K = 100 0C 32 0F = 0 0C 212 0F = 100 0C 0 0C = 32 0F 100 0C = 212 0F

32. 0F – 32 = x 0C 0F = x 0C + 32 x (0F – 32) = 0C 5 5 5 0C = x (0F – 32) 0C = x (172.9 – 32) = 78.3 9 9 9 9 9 5 5 Convert 172.9 0F to degrees Celsius.

33. The number of atoms in 12 g of carbon: 602,200,000,000,000,000,000,000 The mass of a single carbon atom in grams: 0.0000000000000000000000199 Scientific Notation 6.022 x 1023 1.99 x 10-23 N x 10n N is a number between 1 and 10 n is a positive or negative integer

34. move decimal left move decimal right Scientific Notation 568.762 0.00000772 n > 0 n < 0 568.762 = 5.68762 x 102 0.00000772 = 7.72 x 10-6 Addition or Subtraction • Write each quantity with the same exponent n • Combine N1 and N2 • The exponent, n, remains the same 4.31 x 104 + 3.9 x 103 = 4.31 x 104 + 0.39 x 104 = 4.70 x 104

35. Scientific Notation Multiplication (4.0 x 10-5) x (7.0 x 103) = (4.0 x 7.0) x (10-5+3) = 28 x 10-2 = 2.8 x 10-1 • Multiply N1 and N2 • Add exponents n1and n2 Division 8.5 x 104÷ 5.0 x 109 = (8.5 ÷ 5.0) x 104-9= 1.7 x 10-5 • Divide N1 and N2 • Subtract exponents n1and n2

36. Significant Figures • Any digit that is not zerois significant 4 significant figures 1.234 kg • Zeros between nonzero digits are significant 3 significant figures 606 m • Zeros to the left of the first nonzero digit are not significant • 1 significant figure 0.08 L • If a number is greater than 1, then all zeros to the right of the decimal point are significant • 2.0 mg 2 significant figures • If a number is less than 1, then only the zeros that are at the end and in the middle of the number are significant • 0.00420 g 3 significant figures

37. When a number ends in zeros but contains no decimal point, the zeros may or may not be significant. 5000 (one, two, three, or four significant figures) 10,500 (three, four, or five significant figures) The use of exponential notation eliminates the potential ambiguity of whether the zeros at the end of a number are significant 1.03 x 104 Three significant figures 1.030 x 104 Four significant figures Five significant figures 1.0300 x 104

38. How many significant figures are in each of the following measurements? 24 mL 2 significant figures 4 significant figures 3001 g 0.0320 m3 3 significant figures 6.4 x 104 molecules 2 significant figures 560 kg 2 or 3 significant figures 3 significant figures 560. kg

39. 89.332 + 1.1 one significant figure after decimal point two significant figures after decimal point 90.432 round off to 90.4 round off to 0.79 3.70 -2.9133 0.7867 Significant Figures Addition or Subtraction The answer cannot have more digits to the right of the decimal point than any of the original numbers.

40. 3 sig figs round to 3 sig figs 2 sig figs round to 2 sig figs Significant Figures Multiplication or Division The number of significant figures in the result is set by the original number that has the smallest number of significant figures 4.51 x 3.6666 = 16.536366 = 16.5 6.8 ÷ 112.04 = 0.0606926 = 0.061

41. Accuracy – how close a measurement is to the true value Precision – how close a set of measurements are to each other accurate & precise precise but not accurate not accurate & not precise

42. Dimensional Analysis • Determine which unit conversion factor(s) are needed • Carry units through calculation • If all units cancel except for the desired unit(s), then the problem was solved correctly. Desired unit Given unit x Desired unit = Given unit

43. 1000 mL 1L L2 1.63 L x = 1630 mL mL 1L 1.63 L x = 0.001630 1000 mL How many mL are in 1.63 L? 1 L = 1000 mL

44. Remember Desired unit 64 in 64 cm X 2.54 1 in 2.54 cm Desired unit Given unit Given unit x Desired unit = Given unit We know that 1 inch is the same length as 2.54 centimeters. We’re told that the new start of the Indians basketball team is 64 cm tall and that he’s going to be the starting center. Based on height alone we’ll be able to tell if he’ll help the team but we Americans think in INCHES not CENTIMETERS so we need to convert units. = 25.4 in

45. 60 min m x x x 343 60 s 1 mi s 1 hour = 767 1 min 1609 m mi hour The speed of sound in air is about 343 m/s. What is this speed in miles per hour? meters to miles seconds to hours 1 mi = 1609 m 1 min = 60 s 1 hour = 60 min

46. 0.62137 mi 1.0 km 1.0 km 0.62137 mi 3.7854 L 1.0 gal 1.0 gal 3.7854 L Conversion factors A car travels 28 mi per gallon of gasoline. How many kilometer per liter will it go? 1.0 km = 0.62137 mi or or or or 1.0 gal = 3.7854 L

47. 1 km 1.0 km = 0.62137 mi 0.62137 mi 1 gal 1 gal = 3.7854 L 3.7854 L 45 45 mi mi 28 28 gal gal = km km 12 12 km km L L gal gal TWO steps Step 1 x Step 2 x ONE step x x Watch for significant figures. The real number is 11.9 km/L, however, here we have three sig. figures. We have started with a two sig. figure number (28). Thus, the final answer has to have two significant figures!