Branches of Chemistry

1. Branches of Chemistry

2. What is Chemistry? • Study of the composition ofmatterand the changesmatterundergoes • Matter-anything that has mass and takes up space • Why is chemistry such a broad topic?

3. 5 Divisions of chemistry • Organic Chemistry • Study of chemicals containing carbon (anything living) Inorganic Chemistry - Study of chemicals that in general do not contain carbon (nonliving things)

4. Biochemistry • Study of processes that take place in organisms (digestion) Analytical Chemistry - focuses on the composition of matter (What is in drinking water?)

5. Physical Chemistry deals with the mechanism, the rate, and energy transfer when matter undergoes change

6. Physical & Chemical Properties

7. Statistically, 4 years from now, more of you will be here than will have a chemistry degree?

8. Scientific Method • Logical, systematic approach to the solution of a scientific problem. • Making Observations – using your senses to obtain information. An observation can lead to a question. • Making a Hypothesis – a proposed explanation for an observation. A hypothesis is only useful if it accounts for what is actually observed. • Experiment– a procedure that is used to test a hypothesis. • Independent variable – a variable that you change during an experiment

9. Dependent variable – a variable that is observed during the experiment. • For the results of an experiment to be accepted, the experiment must produce the same result no matter how many times it is repeated or by whom. • Developing a Theory – a well-tested explanation for a broad set of observations. • Scientific Law – concise statement that summarized the results of many observations and experiments.

10. Solving Numeric Problems • Analyze – identify what is known and what is unknown. • Calculate – make the calculations. You may need to convert a measurement or rearrange an equation before you can solve. • Evaluate – after you calculate, evaluate your answer. Is the answer reasonable? Does it make sense?

11. Types of Research • Pure or Basic Research • Studying just to study it, furthers knowledge of how and why reactions occur • Ex. crocodile hunter, discovery channel • Applied Research • Attempts to solve a problem, can’t have applied without basic • Ex. Cancer research, baby crocs dying due to weak egg shells

12. Technological Development • Scientific knowledge used to make products that improve the quality of life • Ex. Airplanes, Kevlar

13. Law of Conservation of Matter and Energy • Matter and energy can not be created or destroyed, can change form • Ex. burning wood = • heat + ashes + smoke

14. Properties of Matter • A. Physical- • can be observed without changing the identity of the substance • 1. Extensive Properties- • depend on the amount of the substance • ex. mass, volume

15. Properties of Matter Cont. • 2. Intensive Properties- • does not depend on the amount of the substance • ex. color, texture, luster (shiny), melting and boiling points

16. Density • Density = • mass/volume • density triangle: • Is density a extensive or intensive property?

17. Properties of Matter cont. • B. Chemical Properties- • depends on how a substance reacts with other substances • changes the identity of the substance • ex. reactivity, flammability, rusting, corrosion

18. On the left side of your notebook, list everyday examples of both INTENSIVE and EXSTENSIVE properties

19. Physical and Chemical Changes

20. Changes • A. Physical- • no new substance is formed • a reversal of the process results in the original substance • ex. phase changes: melting, boiling, freezing……. • Dissolving

21. Changes cont. • B. Chemical- • a new substance is formed • the same atoms are present, just in a new arrangement • no atoms are created or destroyed • ex. NaHCO3 + HCl • NaHCO3 + HCl CO2 + H2O + NaCl • What Law is being followed here? • Law of Conservation of Matter and Energy

22. Chemical Change cont. • Any biological function is a chemical change • ex. digesting of food, healing a wound, photosynthesis combustion or burning is also an ex. of a chemical change

23. Evidence of Chemical Change • 1. Fizzing or release of a gas • 2. Color change • 3. Precipitate- insoluble solid formed from 2 solutions • 4. Energy- absorbed or released (ex. heat, light, electricity)

24. Physical or Chemical Change • http://streaming.discoveryeducation.com/search/assetDetail.cfm?guidAssetID=fad11f7c-55a4-458d-addc-cfc4545db433&tabDisplay=myContent

25. Classification of Matter • A. Element • anything on the periodic table • smallest unit of a substance that maintains its unique properties • B. Compound • Chemical combination of 2 or more elements • Water is aCOMPOUND

26. Classification of Matter cont. • C. Mixtures • physical combination of 2 or more substances, each which maintains its own unique properties and can be separated by physical means • 1. Homogeneous- • same composition throughout • ex. air, salt water, kool aid • Compounds are homogeneous

27. Classification of Matter cont. • 2. Heterogeneous- • not the same composition throughout • ex. anything living

29. Phases • A. Solid • definite shape and definite volume, particles packed in fixed positions (draw particles) • B. Liquid • definite volume but indefinite shape, particles close together but not in fixed positions

30. Phases cont. • C. Gases • neither definite volume or definite shape, particles are a great distance from one another

32. Separation Techniques • 1. Distillation- • separates mixtures on the basis of boiling points

33. Separation Techniques cont. • 2. Filtration • separates solid substances from liquids and solutions

34. Separation Techniques cont. • 3. Chromatography- • separates substances on the basis of differences in solubility

35. Changes

36. Types of Chemical Reactions 1. Endothermic- Absorbs energy Will this feel hot or cold? Usually feels cold Products contain more energy than the reactants

37. AX + BY  AY + BX Which side represents the products? The reactants? Takes energy to break bonds and energy is given off when they are formed

38. Products Reactants

39. Endothermic cont. Usually not spontaneous

40. Exothermic Reaction 2. Exothermic- Releases energy Usually feel hot Reactants contain more energy than products

41. More likely spontaneous

43. Very important! • If energy is a product = exothermic • If energy is a reactant = endothermic • One reactant forms two products = endothermic • Two reactants form one product = exothermic

44. Which graph demonstrates an exothermic reaction? Which absorbs energy? Which tends to be spontaneous? Which would tend to feel hot? A B

45. Activation Energy (Ae) The amount of energy necessary to break reactant bonds and initiate the reaction Energy needed in order for the reaction to clear the “hill”

46. Activation Energy (Ae)

48. Example: X + Y + energy → R + S • X and Y have an initial energy of 105 Joules, R and S have a final energy of 425 Joules with an activation energy of 350 Joules. Draw and label the graph that corresponds to this data.

49. Reaction Tendencies

50. Reaction Tendencies- 2 Forces in Nature 1. All reactions seek their lowest energy Ex. Ball rolling down a hill, dropping marker 2. All reactions seek their HIGHESTentropy- Measure of disorder in a system