Chapter 1 “ Introduction to Chemistry”

1. Chapter 1“Introduction to Chemistry” Chapter 2“Matter & Change”

2. What is Chemistry? • Chemistry is the study of the composition of “matter” – (matter is anything with mass and occupies space), its composition, properties, and the changes it undergoes. • Has a definite affect on everyday life - taste of foods, grades of gasoline, etc. • Living and nonliving things are made of matter.

3. Chemistry is the study of the composition, structure, and properties of matter and the changes it undergoes – such as burning fuels. C2H5OH+3O2 2 CO2 + 3 H2O + Energy Reactants  Products

4. 5 Major Areas of Chemistry • Analytical Chemistry- concerned with the composition of substances. • Inorganic Chemistry- primarily deals with substances without carbon • Organic Chemistry- essentially all substances containing carbon • Biochemistry- Chemistry of living things • Physical Chemistry- describes the behavior of chemicals (ex. stretching); involves lots of math! Boundaries not firm – they overlap and interact

5. What is Chemistry? • Pure chemistry- gathers knowledge for the sake of knowledge • Applied Chemistry- is using chemistry to attain certain goals, in fields like medicine, agriculture, and manufacturing – leads to an application * Aspirin (C9H8O4) - to relieve pain * Use of TECHNOLOGY (benefit!)

6. Why Study Chemistry? • Everyone and everything around us involves chemistry – explains our world • What in the world isn’t Chemistry? • Helps you make choices; helps make you a better informed citizen • A possible career for your future • Used to attain a specific goal

7. Why Study Chemistry? • Major component of acid rain • May cause burns • Has been found in tumors • Used in nuclear plants • Used in the distribution of pesticides • Used in animal research

8. Chemistry Far and Wide • Chemists design materials to fit specific needs – velcro(Patented in 1955) • perfume, steel, ceramics, plastics, rubber, paints, nonstick cooking utensils, polyester fibers • Two different ways to look at the world: macroscopic and microscopic

9. Chemistry Far and Wide • Energy – we constantly have greater demands • We can conserve it; use wisely • We can try to produce more; oil from soybeans to make biodiesel • fossil fuels, solar, batteries (that store energy – rechargeable?), nuclear (don’t forget pollution!)

10. Chemistry Far and Wide • Medicine and Biotechnology- • Supply materials doctors use to treat patients • vitamin C, penicillin, aspirin (C9H8O4) • materials for artery transplants and hipbones • bacteria producing insulin

11. Chemistry Far and Wide • Agriculture • Produce the world’s food supply • Use chemistry for better productivity – soil, water, weeds • plant growth hormones • ways to protect crops; insecticides • disease resistant plants

12. Chemistry Far and Wide • The Environment • both risks and benefits involved in discoveries • Pollutants need to be 1) identified and 2) prevented • Lead paint was prohibited in 1978; Leaded gasoline? Drinking water? • carbon dioxide, ozone, global warming

13. Chemistry Far and Wide • The Universe • Need to gather data from afar, and analyze matter brought back to Earth • composition of the planets • analyze moon rocks (or Mars) • planet atmospheres • life on other planets?

14. Alchemy – developed the tools and techniques for working with chemicals • The word chemistry comes from alchemy – practiced in China and India since 400 B.C. • Alchemy has two sides: • Practical: techniques for working with metals, glass, dyes, etc. • Mystical: concepts like perfection – gold was a perfect metal

15. An Experimental Approach • In the 1500s, a shift started from alchemy to science – King Charles II was a supporter of the sciences • “Royal Society of London for the Promotion of Natural Knowledge” • Encouraged scientists to use more experimental evidence, and not philosophical debates

16. Lavoisier • In the late 1700s, Antoine Lavoisier helped transform chemistry from a science of observation to the science of measurement – still used today • He settled a long-standing debate about burning, which was… • Oxygen was required!

17. The Scientific Method • A logical approach to solving problems or answering questions. • Starts with observation- noting and recording information and facts • hypothesis- a proposed explanation for the observation; must be tested by an experiment

18. Steps in the Scientific Method 1. Observations (uses your senses) a)quantitative involves numbers = 95oF b)qualitative is word description = hot 2. Formulating hypotheses (ideas) - possible explanation for the observation, or “educated” guess 3. Performing experiments (the test) - gathers new information to help decide whether the hypothesis is valid

19. Scientific Method • “controlled” experiment- designed to test the hypothesis • only two possible answers: • hypothesis is right (supported) • hypothesis is wrong(not supported) • We gather data and observations by doing the experiment • Modify hypothesis - repeat the cycle

20. Scientific Method • We deal with variables, or factors that can change. Two types: 1) Manipulated variable (or independent variable) is the one that we change 2) Responding variable (or dependent variable) is the one observed during the experiment • For results to be accepted, the experiment needs to always produce the same result

21. Outcomes over the long term… • Theory (Model) - A set of well-tested hypotheses that give an overall explanation of some natural phenomenon – not able to be proved • Natural Law (or Scientific Law) - The same observation applies to many different systems; summarizes results - an example would be: the Law of Conservation of Mass

22. Law vs. Theory • A law summarizes what has happened. • A theory (model) is an attempt to explain why it happened – this changes as new information is gathered.

23. Collaboration / Communication • When scientists share ideas by collaboration and communication, they increase the likelihood of a successful outcome • Collaboration • How is communication done? • Is the Internet reliable information?

24. Luis Alvarez Story • Iridium (30 – 130 times) normal • It’s very rare??? • This layer is found around the planet

25. Luis Alvarez Story ???

26. Luis Alvarez Story X

27. Problem Solving in Chemistry • We are faced with problems each day, and not just in chemistry • A solution (answer) needs to be found • Trial and Error may work sometimes? • But, there is a method to problem solving that works better, and these are skills that no one is born knowing – they need to be learned.

28. Problem Solving in Chemistry • Effective problem solving usually involves two general steps: • Developing a plan • Implementing that plan • The skills you use to solve a word problem in chemistry are NOT different from those techniques used in shopping, cooking, or planning a party.

29. Solving Numeric Problems • Measurements are an important part of chemistry; thus many of our word problems involve use of mathmatics • Word problems are real life problems, and sometimes more information is presented than needed for a solution • Following skills presented will help you become more successful

30. Solving Numeric Problems • The three steps we will use for solving a numeric word problem are: • Analyze • Calculate • Evaluate • The following slides tell the meaning of these three steps in detail. Let’s learn how to ACE these numeric word problems!

31. Solving Numeric Problems • Analyze: this is the starting point • Determine what are the known factors, and write them down on your paper! • Determine what is the unknown. If it is a number, determine the units needed • Plan how to relate these factors- choose an equation; use table or graph • This is the heart of successful problem solving techniques – it is the PLAN

32. Solving Numeric Problems • Calculate:perform the mathematics • If your plan is correct, this is the easiest step. • Calculator used? Do it correctly! • May involve rearranging an equation algebraically; or, doing some conversion of units to some other units.

33. Solving Numeric Problems • Evaluate: – the finishing step • Is it reasonable? Make sense? Do an estimate for the answer, and check your calculations. • Need to round off the answer? • Do you need scientific notation? • Do you have the correct units? • Did you answer the question?

34. Solving Conceptual Problems • Not all word problems in chemistry involve doing calculations • Nonnumeric problems are called conceptual problems – ask you to apply concepts to a new situation • Steps are: • Analyze and 2) Solve • Plan needed to link known to unknown, but no checking units or calculations

35. Matter • Matter is anything that: a) has mass, and b) takes up space • Mass = a measure of the amount of “stuff” (or material) the object contains (don’t confuse this with weight, a measure of gravity) • Volume = a measure of the space occupied by the object

36. Describing Matter • Properties used to describe matter can be classified as: • Extensive – depends on the amount of matter in the sample - Mass, volume, calories are examples • Intensive – depends on the type of matter, not the amount present - Hardness, Density, Boiling Point

37. Properties are… • Words that describe matter (adjectives) • Physical Properties- a property that can be observed and measured without changing the material’s composition. • Examples- color, hardness, m.p., b.p. • Chemical Properties- a property that can only be observed by changing the composition of the material. • Examples- ability to burn, decompose, ferment, react with, etc.

38. States of matter • Solid- matter that can not flow (definite shape) and has definite volume. • Liquid- definite volume but takes the shape of its container (flows). • Gas- a substance without definite volume or shape and can flow. • Vapor- a substance that is currently a gas, but normally is a liquid or solid at room temperature. (Which is correct: “water gas”, or “water vapor”?)

39. States of Matter Result of aTemperatureIncrease? Definite Volume? Definite Shape? Will it Compress? Small Expans. Solid YES YES NO Small Expans. Liquid NO NO YES Large Expans. Gas NO NO YES

40. 4th state:Plasma - formed at high temperatures; ionized phase of matter as found in the sun

41. Three Main Phases

42. Condense Freeze Evaporate Melt Gas Liquid Solid

43. Copper Phases - Solid

44. Copper Phases - Liquid

45. Copper Phases – Vapor (gas)

46. Physical vs. Chemical Change • Physical change will change the visible appearance, without changing the composition of the material. • Boil, melt, cut, bend, split, crack • Is boiled water still water? • Can be reversible, or irreversible • Chemical change - a change where a new form of matter is formed. • Rust, burn, decompose, ferment

47. Mixtures are a physical blend of at least two substances; have variable composition. They can be either: • Heterogeneous – the mixture is not uniform in composition • Chocolate chip cookie, gravel, soil. • Homogeneous - same composition throughout; called “solutions” • Kool-aid, air, salt water • Every part keeps it’s own properties.

48. Solutions are homogeneous mixtures • Mixed molecule by molecule, thus too small to see the different parts • Can occur between any state of matter: gas in gas; liquid in gas; gas in liquid; solid in liquid; solid in solid (alloys), etc. • Thus, based on the distribution of their components, mixtures are called homogeneous or heterogeneous.

49. Phase? • The term “phase” is used to describe any part of a sample with uniform composition of properties. • A homogeneous mixture consists of a single phase • A heterogeneous mixture consists of two or more phases.

50. Separating Mixtures • Some can be separated easily by physical means: rocks and marbles, iron filings and sulfur (use magnet) • Differences in physical properties can be used to separate mixtures. • Filtration - separates a solid from the liquid in a heterogeneous mixture (by size) – Figure 2.7, page 46